feat: codeql

Reviewed-on: #23
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

.gitea/workflows/cd.yaml

@@ -0,0 +1,84 @@
+name: CD
+
+on:
+  push:
+    branches:
+      - main
+
+env:
+  DOCKER_REGISTRY: gitea.t000-n.de
+
+jobs:
+  test:
+    name: test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          check-latest: true
+      - name: Create cache key
+        uses: https://gitea.com/actions/go-hashfiles@v0.0.1
+        id: hash-go
+        with:
+          patterns: |
+            go.mod
+            go.sum
+      - name: cache go
+        id: cache-go
+        uses: actions/cache@v4
+        with:
+          path: |
+            /go_path
+            /go_cache
+          key: go_path-${{ steps.hash-go.outputs.hash }}
+          restore-keys: |-
+            go_cache-${{ steps.hash-go.outputs.hash }}
+      - name: build
+        run: make build
+      - name: test
+        run: make test
+
+  build_and_push:
+    name: Build and push
+    needs:
+      - test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.DOCKER_REGISTRY }}
+          username: ${{ secrets.REGISTRY_USER }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - name: Get Metadata
+        id: meta
+        run: |
+          echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}' | tr '[:upper:]' '[:lower:]') >> $GITHUB_OUTPUT
+          echo REPO_VERSION=$(git describe --tags --always | sed 's/^v//') >> $GITHUB_OUTPUT
+
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: |
+            linux/amd64
+            linux/arm64
+          push: true
+          tags: |
+            ${{ env.DOCKER_REGISTRY }}/t.behrendt/${{ steps.meta.outputs.REPO_NAME }}:${{ steps.meta.outputs.REPO_VERSION }}
+            ${{ env.DOCKER_REGISTRY }}/t.behrendt/${{ steps.meta.outputs.REPO_NAME }}:latest

.gitea/workflows/ci.yaml

@@ -0,0 +1,44 @@
+name: CI
+on:
+  pull_request:
+
+env:
+  GOPATH: /go_path
+  GOCACHE: /go_cache
+  RUNNER_TOOL_CACHE: /toolcache
+
+jobs:
+  test:
+    name: test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          check-latest: true
+      - name: Create cache key
+        uses: https://gitea.com/actions/go-hashfiles@v0.0.1
+        id: hash-go
+        with:
+          patterns: |
+            go.mod
+            go.sum
+      - name: cache go
+        id: cache-go
+        uses: actions/cache@v4
+        with:
+          path: |
+            /go_path
+            /go_cache
+          key: go_path-${{ steps.hash-go.outputs.hash }}
+          restore-keys: |-
+            go_cache-${{ steps.hash-go.outputs.hash }}
+      - name: build
+        run: make build
+      - name: test
+        run: make test
+      - name: check:format
+        run: make check-format

.gitea/workflows/codeql.yaml

@@ -0,0 +1,23 @@
+name: CodeQL Analysis
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  codeql-analysis:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: "go"
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3

.gitignore

@@ -21,3 +21,5 @@
 # Go workspace file
 go.work
 
+.vscode
+config.yaml

Dockerfile

@@ -0,0 +1,13 @@
+FROM golang:1.23-alpine
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+
+RUN go mod download
+
+COPY . .
+
+RUN go build -o main .
+
+CMD ["./main"]

Makefile

@@ -0,0 +1,23 @@
+test:
+	go test ./pkg/... -coverprofile=coverage.out
+
+build:
+	go build
+
+lint:
+	golint ./...
+
+run:
+	make build
+	./realdyndns
+
+format:
+	gofmt -w .
+
+check-format:
+	@OUTPUT=$$(gofmt -l .); \
+	if [ -n "$$OUTPUT" ]; then \
+		echo "Formatter failed for:"; \
+		echo "$$OUTPUT"; \
+		exit 1; \
+	fi

README.md

@@ -1,2 +1,110 @@
 # realDynDNS
 
+RealDynDNS aims to be a replacement to "classical" dynDNS solutions that offer a subdomain. Instead realDynDns actually changes your DNS entries.
+
+This service requires your DNS provider to expose an API that allows your DNS entries to be changed.
+A service that provides your current external IP is also required.
+
+## Configuration
+
+The configuration is done via a YAML file called `config.yaml`. The following example shows the configuration for a domain with two subdomains.
+
+Configuration of the IP provider and the DNS provider is mandatory.
+
+The `check_interval` is mandatory and follows the cron syntax including seconds. It defines how often the IP is checked and the DNS entries are updated. If you don't own the external ip provider, please be nice and don't set the interval too low.
+
+You may configure multiple top level domains with multiple subdomains. If you also want the top level domain to be updated, add it to the subdomains list with an `@`.
+
+```yaml
+ip_provider:
+  type: plain
+  config:
+    url: https://ifconfig.me
+dns_provider:
+  type: ionos
+  config:
+    api_key: <your-api-key>
+    base_url: https://api.hosting.ionos.com/dns
+notification_provider:
+  type: gotify
+  config:
+    url: <your-gotify-host>
+    token: <your-token>
+    priority: 0
+domains:
+  - tld: example.com
+    subdomains:
+      - "@"
+      - www
+check_interval: 0 0 0/6 * * * *
+mode: Scheduled
+log_level: info
+```
+
+The config file is expected to be in the same directory as the binary and called `config.yaml`. For the OCR image, the root directory is `/app`.
+
+## DNS Providers
+
+The DNS provider abstracts the API of your DNS provider. Currently the following providers are supported:
+
+### IONOS
+
+IONOS requires two configuration parameters. You can get your API key [here](https://developer.hosting.ionos.com/docs/getstarted).
+
+```yaml
+api_key: <your-api-key>
+base_url: https://api.hosting.ionos.com/dns
+```
+
+## External IP Providers
+
+The external IP provider is used to get your current external IP. Currently the following providers are supported:
+
+### Plain
+
+Any provider that returns your IP as plain text can be used. The following configuration is required:
+
+```yaml
+url: <your-providers-URL>
+```
+
+Examples for providers are:
+
+- https://ifconfig.me
+- https://api.ipify.org
+
+## Notification Providers
+
+The notification provider is used to send notifications whena IP address changes and a DNS record is updated.
+
+### Console
+
+The console notification provider is used to print the notification to the console. This is the default notification provider.
+
+### Gotify
+
+The Gotify notification provider is used to send notifications to a Gotify server.
+
+```yaml
+url: <your-gotify-host>
+token: <your-token>
+priority: 0
+```
+
+The priority must be between 0 and 4.
+
+## Mode Selection
+
+Two modes are available:
+
+### RunOnce
+
+The RunOnce mode is used to run the application once and exit. This is useful when providing your own external scheduler, like cron.
+
+Set the `mode` to `RunOnce`.
+
+### Scheduled
+
+The Scheduled mode is used to run the application in a scheduled interval.
+
+Set the `mode` to `Scheduled` and provide a cron expression for the `check_interval`.

config.example.yaml

@@ -0,0 +1,24 @@
+---
+ip_provider:
+  type: plain
+  config:
+    url: https://api.ipify.org
+dns_provider:
+  type: ionos
+  config:
+    api_key: <your-api-key>
+    base_url: https://api.hosting.ionos.com/dns
+notification_provider:
+  type: gotify
+  config:
+    url: <your-gotify-host>
+    token: <your-token>
+    priority: 0
+domains:
+  - tld: example.com
+    subdomains:
+      - "@"
+      - www
+check_interval: 0 0 0/6 * * * *
+mode: Scheduled
+log_level: info

go.mod

@@ -0,0 +1,15 @@
+module realdnydns
+
+go 1.23
+
+require (
+	github.com/go-co-op/gocron v1.37.0
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/robfig/cron/v3 v3.0.1 // indirect
+	github.com/stretchr/testify v1.8.4 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
+)

go.sum

@@ -0,0 +1,45 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-co-op/gocron v1.37.0 h1:ZYDJGtQ4OMhTLKOKMIch+/CY70Brbb1dGdooLEhh7b0=
+github.com/go-co-op/gocron v1.37.0/go.mod h1:3L/n6BkO7ABj+TrfSVXLRzsP26zmikL4ISkLQ0O8iNY=
+github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
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+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -0,0 +1,142 @@
+package main
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"strings"
+
+	"realdnydns/pkg/config"
+	"realdnydns/pkg/dnsProvider"
+	ionos "realdnydns/pkg/dnsProvider/ionos"
+	"realdnydns/pkg/externalIpProvider"
+	plainExternalIpProvider "realdnydns/pkg/externalIpProvider/plain"
+	"realdnydns/pkg/notificationProvider"
+	notificationProviderConsole "realdnydns/pkg/notificationProvider/console"
+	gotify "realdnydns/pkg/notificationProvider/gotify"
+	"realdnydns/pkg/realDynDns"
+)
+
+func main() {
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelInfo,
+	}))
+
+	configClient := config.Config{}
+	err := configClient.Load("config.yaml")
+	if err != nil {
+		logger.Error("Failed to load config file", slog.String("error", err.Error()))
+		panic(err)
+	}
+
+	if configClient.LogLevel != "" {
+		logger = slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+			Level: slog.Level(config.LogLevelMap[strings.ToLower(configClient.LogLevel)]),
+		}))
+	}
+
+	var externalIpProvider externalIpProvider.ExternalIpProvider
+	switch configClient.ExternalIPProvider.Type {
+	case "plain":
+		logger.Info("Using plain external IP provider", slog.String("external_ip_provider", "plain"))
+
+		var plainConfig plainExternalIpProvider.PlainExternalIpProviderConfig
+		err := configClient.ExternalIPProvider.ProviderConfig.Decode(&plainConfig)
+		if err != nil {
+			logger.Error("Failed to create config",
+				slog.String("external_ip_provider", "plain"),
+				slog.String("error", err.Error()),
+			)
+			panic(err)
+		}
+
+		externalIpProvider, err = plainExternalIpProvider.New(plainConfig)
+		if err != nil {
+			logger.Error("Failed to create plain external IP provider",
+				slog.String("external_ip_provider", "plain"),
+				slog.String("error", err.Error()),
+			)
+			panic(err)
+		}
+	default:
+		logger.Error("Unknown external IP provider", slog.String("external_ip_provider", configClient.ExternalIPProvider.Type))
+		panic(fmt.Errorf("unknown external IP provider: %s", configClient.ExternalIPProvider.Type))
+	}
+
+	var dnsProvider dnsProvider.DNSProvider
+	switch configClient.DNSProvider.Type {
+	case "ionos":
+		logger.Info("Using IONOS DNS provider", slog.String("dns_provider", "ionos"))
+
+		var ionosConfig ionos.IONOSConfig
+		err := configClient.DNSProvider.ProviderConfig.Decode(&ionosConfig)
+		if err != nil {
+			logger.Error("Failed to create IONOS DNS provider",
+				slog.String("dns_provider", "ionos"),
+				slog.String("error", err.Error()),
+			)
+			panic(err)
+		}
+
+		dnsProvider, err = ionos.NewIonos(&ionosConfig)
+		if err != nil {
+			logger.Error("Failed to create IONOS DNS provider",
+				slog.String("dns_provider", "ionos"),
+				slog.String("error", err.Error()),
+			)
+			panic(err)
+		}
+	default:
+		logger.Error("Unknown DNS provider", slog.String("dns_provider", configClient.DNSProvider.Type))
+		panic(fmt.Errorf("unknown DNS provider: %s", configClient.DNSProvider.Type))
+	}
+
+	var notificationProvider notificationProvider.NotificationProvider
+	switch configClient.NotificationProvider.Type {
+	case "gotify":
+		logger.Info("Using Gotify notification provider", slog.String("notification_provider", "gotify"))
+
+		var gotifyConfig gotify.NotificationProviderImplGotifyConfig
+		err := configClient.NotificationProvider.ProviderConfig.Decode(&gotifyConfig)
+		if err != nil {
+			panic(err)
+		}
+
+		notificationProvider, err = gotify.New(gotifyConfig)
+		if err != nil {
+			logger.Error("Failed to create Gotify notification provider",
+				slog.String("notification_provider", "gotify"),
+				slog.String("error", err.Error()),
+			)
+			panic(err)
+		}
+	default:
+		logger.Info("Using console notification provider", slog.String("notification_provider", "console"))
+
+		notificationProvider = notificationProviderConsole.New()
+	}
+
+	rdd := realDynDns.New(externalIpProvider, dnsProvider, notificationProvider, configClient.Domains, logger.With(slog.String("service", "realDynDns")))
+
+	switch configClient.Mode {
+	case config.ScheduledMode:
+		logger.Info("Running in scheduled mode", slog.String("interval", configClient.CheckInterval))
+
+		schedule, job, err := rdd.RunWithSchedule(configClient.CheckInterval)
+		if err != nil {
+			logger.Error("Failed to create scheduler", slog.String("error", err.Error()))
+			panic(err)
+		}
+
+		logger.Info("Next run:", slog.String("time", job.NextRun().String()))
+		schedule.StartBlocking()
+	case config.RunOnceMode:
+		logger.Info("Running in run once mode")
+
+		_, err := rdd.RunOnce()
+		if err != nil {
+			logger.Error("Failed to run once", slog.String("error", err.Error()))
+			panic(err)
+		}
+	}
+}

model/common/common.go

@@ -0,0 +1,9 @@
+package common
+
+type ARecord struct {
+	Domain   string
+	IP       string
+	TTL      int
+	Prio     int
+	Disabled bool
+}

pkg/config/__mocks__/testLoadCanFindFile.yaml

@@ -0,0 +1,15 @@
+ip_provider:
+  type: plain
+  config:
+    url: https://example.com
+dns_provider:
+  type: ionos
+  config:
+    api_key: exampleapikey
+    base_url: https://example.com
+domains:
+  - tld: example.com
+    subdomains:
+      - "@"
+check_interval: 0 0 * * * *
+mode: RunOnce

pkg/config/__mocks__/testLoadInvalidMode.yaml

@@ -0,0 +1,2 @@
+mode: "InvalidMode"
+check_interval: "5m"

pkg/config/__mocks__/testLoadInvalidYAML.yaml

@@ -0,0 +1,3 @@
+mode: "Scheduled"
+check_interval: "5m"
+- invalid_content

pkg/config/__mocks__/testLoadMissingCheckInterval.yaml

@@ -0,0 +1,3 @@
+mode: "Scheduled"
+ip_provider:
+  type: "plain"

pkg/config/config.go

@@ -0,0 +1,91 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"log/slog"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	Mode                 string                     `yaml:"mode"`
+	ExternalIPProvider   ExternalIpProviderConfig   `yaml:"ip_provider"`
+	DNSProvider          DNSProviderConfig          `yaml:"dns_provider"`
+	NotificationProvider NotificationProviderConfig `yaml:"notification_provider,omitempty"`
+	Domains              []DomainConfig             `yaml:"domains"`
+	CheckInterval        string                     `yaml:"check_interval"`
+	LogLevel             string                     `yaml:"log_level"`
+}
+
+const (
+	RunOnceMode   = "RunOnce"
+	ScheduledMode = "Scheduled"
+)
+
+var LogLevelMap = map[string]slog.Level{
+	"debug": slog.LevelDebug,
+	"info":  slog.LevelInfo,
+	"warn":  slog.LevelWarn,
+	"error": slog.LevelError,
+}
+
+func isValidLogLevel(level string) bool {
+	_, ok := LogLevelMap[strings.ToLower(level)]
+	return ok
+}
+
+type DomainConfig struct {
+	TLD        string   `yaml:"tld"`
+	Subdomains []string `yaml:"subdomains"`
+}
+
+type ExternalIpProviderConfig struct {
+	Type           string    `yaml:"type"`
+	ProviderConfig yaml.Node `yaml:"config"`
+}
+
+type DNSProviderConfig struct {
+	Type           string    `yaml:"type"`
+	ProviderConfig yaml.Node `yaml:"config"`
+}
+
+type NotificationProviderConfig struct {
+	Type           string    `yaml:"type"`
+	ProviderConfig yaml.Node `yaml:"config"`
+}
+
+func (c *Config) Load(filePath string) error {
+	inputConfig, err := os.ReadFile(filePath)
+	if err != nil {
+		return fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	if err := yaml.Unmarshal(inputConfig, c); err != nil {
+		return fmt.Errorf("failed to unmarshal config file: %w", err)
+	}
+
+	if err := c.validate(); err != nil {
+		return fmt.Errorf("failed to validate config: %w", err)
+	}
+
+	return nil
+}
+
+func (c *Config) validate() error {
+	if c.Mode != RunOnceMode && c.Mode != ScheduledMode {
+		return errors.New("mode must be one of 'RunOnce' or 'Scheduled'")
+	}
+
+	if c.Mode == ScheduledMode && c.CheckInterval == "" {
+		return errors.New("check interval must be set when mode is 'Scheduled'")
+	}
+
+	if c.LogLevel != "" && !isValidLogLevel(c.LogLevel) {
+		return fmt.Errorf("log level must be one of 'debug', 'info', 'warn', 'error', but got %s", c.LogLevel)
+	}
+
+	return nil
+}

pkg/config/config_test.go

@@ -0,0 +1,52 @@
+package config
+
+import (
+	"fmt"
+	"testing"
+)
+
+func testFactoryFileRelatedError(fileName string, expectedErrorText string) func(t *testing.T) {
+	return func(t *testing.T) {
+		c := Config{}
+		err := c.Load(fmt.Sprintf("./__mocks__/%s", fileName))
+
+		want := err != nil && err.Error() == expectedErrorText
+
+		if !want {
+			t.Fatalf("Expected error message %s, but got %s", expectedErrorText, err.Error())
+		}
+	}
+}
+
+func TestLoad(t *testing.T) {
+	t.Run("Can find file", testLoadCanFindFile())
+	t.Run("Cannot find file", testFactoryFileRelatedError(
+		"nonexistent.yaml",
+		"failed to read config file: open ./__mocks__/nonexistent.yaml: no such file or directory",
+	))
+	t.Run("Missing CheckInterval in Scheduled mode", testFactoryFileRelatedError(
+		"testLoadMissingCheckInterval.yaml",
+		"failed to validate config: check interval must be set when mode is 'Scheduled'",
+	))
+	t.Run("Invalid mode", testFactoryFileRelatedError(
+		"testLoadInvalidMode.yaml",
+		"failed to validate config: mode must be one of 'RunOnce' or 'Scheduled'",
+	))
+	t.Run("Invalid YAML", testFactoryFileRelatedError(
+		"testLoadInvalidYAML.yaml",
+		"failed to unmarshal config file: yaml: line 2: did not find expected key",
+	))
+}
+
+func testLoadCanFindFile() func(t *testing.T) {
+	return func(t *testing.T) {
+		c := Config{}
+		err := c.Load("./__mocks__/testLoadCanFindFile.yaml")
+
+		want := err == nil && c.DNSProvider.Type == "ionos" && c.ExternalIPProvider.Type == "plain" && c.Mode == "RunOnce"
+
+		if !want || err != nil {
+			t.Fatalf("Failed to load config file, expected no errors but got: %s", err)
+		}
+	}
+}

pkg/dnsProvider/__mocks__/testNewCanCreateIonosProvider.yaml

@@ -0,0 +1,16 @@
+---
+ip_provider:
+  type: plain
+  config:
+    url: https://ifconfig.me
+dns_provider:
+  type: ionos
+  config:
+    api_key: exampleAPIKey
+    base_url: https://example.com
+domains:
+  - tld: example.com
+    subdomains:
+      - "@"
+      - www
+check_interval: 0 0 0/6 * * * *

pkg/dnsProvider/dnsProvider.go

@@ -0,0 +1,11 @@
+package dnsProvider
+
+import (
+	"net"
+	"realdnydns/model/common"
+)
+
+type DNSProvider interface {
+	UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error)
+	GetRecord(tld string, subdomain string) (*common.ARecord, error)
+}

pkg/dnsProvider/ionos/api/ionosAPI.go

@@ -0,0 +1,224 @@
+package ionosAPI
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"realdnydns/model/common"
+)
+
+/**
+ * Docs: https://developer.hosting.ionos.com/docs/dns
+ */
+type IonosAPI interface {
+	GetARecord(tld string, subdomain string) (*common.ARecord, error)
+	SetARecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error)
+	GetZoneId(tld string) (string, error)
+	GetRecordId(zoneId string, tld string, subdomain string, recordType string) (string, error)
+	HttpCall(method string, url string, body io.Reader, queryParams map[string]string) (*http.Response, error)
+}
+
+type IonosAPIImpl struct {
+	APIKey     string
+	BaseURL    string
+	HTTPClient *http.Client
+}
+
+type ZonesResponse []struct {
+	Name string `json:"name"`
+	Id   string `json:"id"`
+	Type string `json:"type"`
+}
+
+type ZoneResponse struct {
+	Id      string           `json:"id"`
+	Name    string           `json:"name"`
+	Type    string           `json:"type"`
+	Records []RecordResponse `json:"records"`
+}
+
+type RecordResponse struct {
+	Id         string `json:"id"`
+	Name       string `json:"name"`
+	RootName   string `json:"rootName"`
+	Type       string `json:"type"`
+	Content    string `json:"content"`
+	ChangeDate string `json:"changeDate"`
+	TTL        int    `json:"ttl"`
+	Prio       int    `json:"prio"`
+	Disabled   bool   `json:"disabled"`
+}
+
+type ChangeRecord struct {
+	Name     string `json:"name"`
+	Type     string `json:"type"`
+	Content  string `json:"content"`
+	TTL      int    `json:"ttl"`
+	Prio     int    `json:"prio"`
+	Disabled bool   `json:"disabled"`
+}
+
+type ChangeRecordRequest struct {
+	Content  string `json:"content"`
+	TTL      int    `json:"ttl"`
+	Prio     int    `json:"prio"`
+	Disabled bool   `json:"disabled"`
+}
+
+func New(APIKey string, BaseURL string) IonosAPI {
+	return &IonosAPIImpl{
+		APIKey:     APIKey,
+		BaseURL:    BaseURL,
+		HTTPClient: &http.Client{},
+	}
+}
+
+func (i *IonosAPIImpl) HttpCall(method string, path string, body io.Reader, queryParams map[string]string) (*http.Response, error) {
+	requestUrl, _ := url.Parse(i.BaseURL + path)
+
+	query := requestUrl.Query()
+	for key, value := range queryParams {
+		query.Add(key, value)
+	}
+	requestUrl.RawQuery = query.Encode()
+
+	req, err := http.NewRequest(method, requestUrl.String(), body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Add("X-API-Key", i.APIKey)
+	req.Header.Add("Content-Type", "application/json")
+	req.Header.Add("Accept", "application/json")
+
+	return i.HTTPClient.Do(req)
+}
+
+func (i *IonosAPIImpl) GetZoneId(tld string) (string, error) {
+	res, err := i.HttpCall("GET", "/v1/zones", nil, nil)
+	if err != nil {
+		return "", err
+	}
+
+	responseBody := make([]byte, res.ContentLength)
+	res.Body.Read(responseBody)
+
+	zones := []ZoneResponse{}
+	json.Unmarshal(responseBody, &zones)
+
+	for _, z := range zones {
+		if z.Name == tld {
+			return z.Id, nil
+		}
+	}
+
+	return "", errors.New("zone not found")
+}
+
+func (i *IonosAPIImpl) GetRecordId(zoneId string, tld string, subdomain string, recordType string) (string, error) {
+	var domain string
+	if subdomain == "@" || subdomain == "" {
+		domain = tld
+	} else {
+		domain = subdomain + "." + tld
+	}
+
+	res, err := i.HttpCall("GET", "/v1/zones/"+zoneId, nil, map[string]string{"recordName": domain, "recordType": recordType})
+	if err != nil {
+		return "", err
+	}
+
+	responseBody := make([]byte, res.ContentLength)
+	res.Body.Read(responseBody)
+
+	zone := ZoneResponse{}
+	json.Unmarshal(responseBody, &zone)
+
+	for _, record := range zone.Records {
+		if record.Type == recordType && record.Name == domain {
+			return record.Id, nil
+		}
+	}
+
+	return "", errors.New("record not found")
+}
+
+func (i *IonosAPIImpl) SetARecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+	zoneId, err := i.GetZoneId(tld)
+	if err != nil {
+		return nil, err
+	}
+
+	recordId, err := i.GetRecordId(zoneId, tld, subdomain, "A")
+	if err != nil {
+		return nil, err
+	}
+
+	changeRecordRequest, err := json.Marshal(ChangeRecordRequest{
+		Content:  ip.String(),
+		TTL:      ttl,
+		Prio:     prio,
+		Disabled: false,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	res, err := i.HttpCall("PUT", "/v1/zones/"+zoneId+"/records/"+recordId, bytes.NewReader(changeRecordRequest), nil)
+	if err != nil {
+		return nil, err
+	}
+
+	responseBody := make([]byte, res.ContentLength)
+	res.Body.Read(responseBody)
+
+	if res.StatusCode != 200 {
+		return nil, errors.New("error updating record")
+	}
+
+	changeRecord := ChangeRecord{}
+	json.Unmarshal(responseBody, &changeRecord)
+
+	return &common.ARecord{
+		Domain:   changeRecord.Name,
+		IP:       changeRecord.Content,
+		TTL:      changeRecord.TTL,
+		Prio:     changeRecord.Prio,
+		Disabled: changeRecord.Disabled,
+	}, nil
+}
+
+func (ionos *IonosAPIImpl) GetARecord(tld string, subdomain string) (*common.ARecord, error) {
+	zoneId, err := ionos.GetZoneId(tld)
+	if err != nil {
+		return nil, err
+	}
+
+	recordId, err := ionos.GetRecordId(zoneId, tld, subdomain, "A")
+	if err != nil {
+		return nil, err
+	}
+
+	res, err := ionos.HttpCall("GET", "/v1/zones/"+zoneId+"/records/"+recordId, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	responseBody := make([]byte, res.ContentLength)
+	res.Body.Read(responseBody)
+
+	record := RecordResponse{}
+	json.Unmarshal(responseBody, &record)
+
+	return &common.ARecord{
+		Domain:   record.Name,
+		IP:       record.Content,
+		TTL:      record.TTL,
+		Prio:     record.Prio,
+		Disabled: record.Disabled,
+	}, nil
+}

pkg/dnsProvider/ionos/api/ionosAPI_test.go

@@ -0,0 +1,285 @@
+package ionosAPI
+
+import (
+	"encoding/json"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func utilMockServerImpl() func(w http.ResponseWriter, r *http.Request) {
+	zonesResponse := []ZoneResponse{
+		{
+			Name: "example.com",
+			Id:   "1234567890",
+			Type: "NATIVE",
+		},
+		{
+			Name: "notTheExample.org",
+			Id:   "0987654321",
+			Type: "SLAVE",
+		},
+	}
+	zonesResponseJson, _ := json.Marshal(zonesResponse)
+
+	recordResponseSub := RecordResponse{
+		Id:         "abcdefghij",
+		Name:       "example.com",
+		RootName:   "example.com",
+		Type:       "A",
+		Content:    "127.0.0.1",
+		ChangeDate: "2019-12-09T13:04:25.772Z",
+		TTL:        300,
+		Prio:       0,
+		Disabled:   false,
+	}
+	recordResponseSubJson, _ := json.Marshal(recordResponseSub)
+
+	recordResponseTLD := RecordResponse{
+		Id:         "jihgfedcba",
+		Name:       "sub.example.com",
+		RootName:   "example.com",
+		Type:       "A",
+		Content:    "127.0.0.2",
+		ChangeDate: "2019-12-09T13:04:25.772Z",
+		TTL:        300,
+		Prio:       0,
+		Disabled:   false,
+	}
+	recordResponseTLDJson, _ := json.Marshal(recordResponseTLD)
+
+	zoneResponse := ZoneResponse{
+		Id:   "1234567890",
+		Name: "example.com",
+		Type: "NATIVE",
+		Records: []RecordResponse{
+			recordResponseSub,
+			recordResponseTLD,
+		},
+	}
+	zoneResponseJson, _ := json.Marshal(zoneResponse)
+
+	changeRecord := ChangeRecord{
+		Name:     "sub.example.com",
+		Type:     "A",
+		Content:  "127.0.0.1",
+		TTL:      300,
+		Prio:     0,
+		Disabled: false,
+	}
+	changeRecordJson, _ := json.Marshal(changeRecord)
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		var response []byte
+
+		if r.Method == "GET" {
+			if r.RequestURI == "/v1/zones" {
+				response = zonesResponseJson
+			} else if r.RequestURI == "/v1/zones/1234567890?recordName=example.com&recordType=A" ||
+				r.RequestURI == "/v1/zones/1234567890?recordName=sub.example.com&recordType=A" {
+				response = zoneResponseJson
+			} else if r.RequestURI == "/v1/zones/1234567890/records/abcdefghij" {
+				response = recordResponseSubJson
+			} else if r.RequestURI == "/v1/zones/1234567890/records/jihgfedcba" {
+				response = recordResponseTLDJson
+			}
+		} else if r.Method == "PUT" {
+			response = changeRecordJson
+		} else {
+			response = []byte("404")
+		}
+
+		w.Write(response)
+	}
+}
+
+func TestHttpCall(t *testing.T) {
+	mockServer := httptest.NewServer(http.HandlerFunc(utilMockServerImpl()))
+	defer mockServer.Close()
+
+	ionosAPI := New("dummyKey", mockServer.URL)
+
+	t.Run("returns response for GET request", testHttpCallGet(ionosAPI))
+	t.Run("returns response for PUT request", testHttpCallPut(ionosAPI))
+	t.Run("returns error for non existing endpoint", testHttpCallNonExistingEndpoint())
+}
+
+func testHttpCallGet(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		res, err := api.HttpCall("GET", "/v1/zones", nil, nil)
+
+		if err != nil {
+			t.Fatalf("HttpCall() returned unexpected error: %v", err)
+		}
+
+		if res.StatusCode != 200 {
+			t.Fatalf("HttpCall() returned unexpected status code: %v instead of 200", res.StatusCode)
+		}
+	}
+}
+
+func testHttpCallPut(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		res, err := api.HttpCall("PUT", "/v1/zones/1234567890/records/abcdefghij", nil, nil)
+
+		if err != nil {
+			t.Fatalf("HttpCall() returned unexpected error: %v", err)
+		}
+
+		if res.StatusCode != 200 {
+			t.Fatalf("HttpCall() returned unexpected status code: %v instead of 200", res.StatusCode)
+		}
+	}
+}
+
+func testHttpCallNonExistingEndpoint() func(t *testing.T) {
+	return func(t *testing.T) {
+		mockServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(404)
+		}))
+		defer mockServer.Close()
+
+		api := New("dummyKey", mockServer.URL)
+
+		res, err := api.HttpCall("GET", "/v1/nonExistingEndpoint", nil, nil)
+
+		if err != nil {
+			t.Fatalf("HttpCall() returned unexpected error: %v", err)
+		}
+
+		if res.StatusCode != 404 {
+			t.Fatalf("HttpCall() returned unexpected status code: %v instead of 404", res.StatusCode)
+		}
+	}
+}
+
+func TestGetZoneId(t *testing.T) {
+	mockServer := httptest.NewServer(http.HandlerFunc(utilMockServerImpl()))
+
+	ionosAPI := New("dummyKey", mockServer.URL)
+
+	t.Run("returns zoneId for tracked domain", testGetZoneIdSuccess(ionosAPI))
+	t.Run("returns error for non tracked domain", testGetZoneIdNoMatch(ionosAPI))
+}
+
+func testGetZoneIdSuccess(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		zoneId, err := api.GetZoneId("example.com")
+
+		if err != nil {
+			t.Fatalf("GetZoneId() returned unexpected error: %v", err)
+		}
+
+		if zoneId != "1234567890" {
+			t.Fatalf("GetZoneId() returned unexpected zoneId: %v instead of 1234567890", zoneId)
+		}
+	}
+}
+
+func testGetZoneIdNoMatch(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		zoneId, err := api.GetZoneId("nonTrackedDomain.com")
+
+		if err == nil || zoneId != "" {
+			t.Fatalf("GetZoneId() did not return an error for a non tracked domain")
+		}
+	}
+}
+
+func TestGetRecordId(t *testing.T) {
+	mockServer := httptest.NewServer(http.HandlerFunc(utilMockServerImpl()))
+	defer mockServer.Close()
+
+	ionosAPI := New("dummyKey", mockServer.URL)
+
+	t.Run("returns zoneId for top level domain", testGetRecordIdForTopLevelDomain(ionosAPI))
+	t.Run("returns zoneId for subdomain", testGetRecordIdForSubdomain(ionosAPI))
+	t.Run("returns error for untracked subdomain", testGetRecordIdWithUntrackedSubdomain(ionosAPI))
+}
+
+func testGetRecordIdForTopLevelDomain(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		recordId, err := api.GetRecordId("1234567890", "example.com", "", "A")
+
+		if err != nil {
+			t.Fatalf("GetZoneId() returned unexpected error: %v", err)
+		}
+
+		if recordId != "abcdefghij" {
+			t.Fatalf("GetZoneId() returned unexpected zoneId: %v instead of abcdefghij", recordId)
+		}
+	}
+}
+
+func testGetRecordIdForSubdomain(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		recordId, err := api.GetRecordId("1234567890", "example.com", "sub", "A")
+
+		if err != nil {
+			t.Fatalf("GetZoneId() returned unexpected error: %v", err)
+		}
+
+		if recordId != "jihgfedcba" {
+			t.Fatalf("GetZoneId() returned unexpected zoneId: %v instead of jihgfedcba", recordId)
+		}
+	}
+}
+
+func testGetRecordIdWithUntrackedSubdomain(api IonosAPI) func(t *testing.T) {
+	return func(t *testing.T) {
+		recordId, err := api.GetRecordId("1234567890", "example.com", "untrackedSub", "A")
+
+		if err == nil && recordId == "" {
+			t.Fatalf("GetZoneId() did not return an error for a non tracked domain")
+		}
+	}
+}
+
+func TestGetARecord(t *testing.T) {
+	mockServer := httptest.NewServer(http.HandlerFunc(utilMockServerImpl()))
+	defer mockServer.Close()
+
+	ionosAPI := New("dummyKey", mockServer.URL)
+
+	t.Run("returns A record for top level domain", testGetARecordFor(ionosAPI, "example.com", ""))
+	t.Run("returns A record for subdomain", testGetARecordFor(ionosAPI, "example.com", "sub"))
+}
+
+func testGetARecordFor(api IonosAPI, tld string, subdomain string) func(t *testing.T) {
+	return func(t *testing.T) {
+		var domain string
+		if subdomain == "" {
+			domain = tld
+		} else {
+			domain = subdomain + "." + tld
+		}
+
+		record, err := api.GetARecord(tld, subdomain)
+
+		if err != nil {
+			t.Fatalf("GetARecord() returned unexpected error: %v", err)
+		}
+
+		if record.Domain != domain {
+			t.Fatalf("GetARecord() returned unexpected record for: %v instead of %v", record.Domain, domain)
+		}
+	}
+}
+
+func TestSetARecord(t *testing.T) {
+	mockServer := httptest.NewServer(http.HandlerFunc(utilMockServerImpl()))
+	defer mockServer.Close()
+
+	ionosAPI := New("dummyKey", mockServer.URL)
+
+	changedARecord, err := ionosAPI.SetARecord("example.com", "sub", net.ParseIP("127.0.0.1"), 300, 0, false)
+
+	if err != nil {
+		t.Fatalf("SetARecord() returned unexpected error: %v", err)
+	}
+
+	if changedARecord.Domain != "sub.example.com" {
+		t.Fatalf("SetARecord() returned unexpected record for: %v instead of sub.example.com", changedARecord.Domain)
+	}
+}

pkg/dnsProvider/ionos/ionos.go

@@ -0,0 +1,40 @@
+package ionosDnsProvider
+
+import (
+	"errors"
+	"net"
+	"realdnydns/model/common"
+	"realdnydns/pkg/dnsProvider"
+	ionosAPI "realdnydns/pkg/dnsProvider/ionos/api"
+)
+
+type IONOS struct {
+	API ionosAPI.IonosAPI
+}
+
+type IONOSConfig struct {
+	APIKey  string `yaml:"api_key"`
+	BaseURL string `yaml:"base_url"`
+}
+
+func NewIonos(config *IONOSConfig) (dnsProvider.DNSProvider, error) {
+	if config.APIKey == "" {
+		return nil, errors.New("api_key is required")
+	}
+
+	if config.BaseURL == "" {
+		return nil, errors.New("base_url is required")
+	}
+
+	return &IONOS{
+		ionosAPI.New(config.APIKey, config.BaseURL),
+	}, nil
+}
+
+func (ionos *IONOS) UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+	return ionos.API.SetARecord(tld, subdomain, ip, ttl, prio, disabled)
+}
+
+func (ionos *IONOS) GetRecord(tld string, subdomain string) (*common.ARecord, error) {
+	return ionos.API.GetARecord(tld, subdomain)
+}

pkg/dnsProvider/ionos/ionos_test.go

@@ -0,0 +1,225 @@
+package ionosDnsProvider_test
+
+import (
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	common "realdnydns/model/common"
+	ionosDnsProvider "realdnydns/pkg/dnsProvider/ionos"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	//t.Run("Config cannot be decoded", testNewConfigCannotBeDecoded())
+	t.Run("API key is required", testNewAPIKeyIsRequired())
+	t.Run("Base URL is required", testNewBaseURLIsRequired())
+	t.Run("Valid config", testNewValidConfig())
+}
+
+func testNewAPIKeyIsRequired() func(*testing.T) {
+	return func(t *testing.T) {
+		config := ionosDnsProvider.IONOSConfig{
+			BaseURL: "https://api.ionos.com",
+		}
+
+		_, err := ionosDnsProvider.NewIonos(&config)
+		if err == nil {
+			t.Error("Expected error, got nil")
+		}
+	}
+}
+
+func testNewBaseURLIsRequired() func(*testing.T) {
+	return func(t *testing.T) {
+		config := ionosDnsProvider.IONOSConfig{
+			APIKey: "1234",
+		}
+
+		_, err := ionosDnsProvider.NewIonos(&config)
+		if err == nil {
+			t.Error("Expected error, got nil")
+		}
+
+	}
+}
+
+func testNewValidConfig() func(*testing.T) {
+	return func(t *testing.T) {
+		config := ionosDnsProvider.IONOSConfig{
+			APIKey:  "1234",
+			BaseURL: "https://api.ionos.com",
+		}
+
+		_, err := ionosDnsProvider.NewIonos(&config)
+		if err != nil {
+			t.Errorf("Expected nil, got %v", err)
+		}
+	}
+}
+
+type MockIonosAPI struct {
+	SetARecordFunc  func(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error)
+	GetARecordFunc  func(tld string, subdomain string) (*common.ARecord, error)
+	GetRecordIdFunc func(zoneId string, tld string, subdomain string, recordType string) (string, error)
+	GetZoneIdFunc   func(tld string) (string, error)
+	HttpCallFunc    func(method string, url string, body io.Reader) (*http.Response, error)
+}
+
+func (m *MockIonosAPI) SetARecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+	return m.SetARecordFunc(tld, subdomain, ip, ttl, prio, disabled)
+}
+
+func (m *MockIonosAPI) GetARecord(tld string, subdomain string) (*common.ARecord, error) {
+	return m.GetARecordFunc(tld, subdomain)
+}
+
+func (m *MockIonosAPI) GetRecordId(zoneId string, tld string, subdomain string, recordType string) (string, error) {
+	return m.GetRecordIdFunc(zoneId, tld, subdomain, recordType)
+}
+
+func (m *MockIonosAPI) GetZoneId(tld string) (string, error) {
+	return m.GetZoneIdFunc(tld)
+}
+
+func (m *MockIonosAPI) HttpCall(method string, url string, body io.Reader, queryParams map[string]string) (*http.Response, error) {
+	return m.HttpCallFunc(method, url, body)
+}
+
+func TestUpdateRecord(t *testing.T) {
+	t.Run("API error", testUpdateRecordAPIError())
+	t.Run("API success", testUpdateRecordAPISuccess())
+}
+
+func testUpdateRecordAPIError() func(*testing.T) {
+	return func(t *testing.T) {
+		api := &MockIonosAPI{
+			SetARecordFunc: func(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+				return nil, errors.New("API error")
+			},
+		}
+
+		provider := ionosDnsProvider.IONOS{
+			API: api,
+		}
+
+		_, err := provider.UpdateRecord("example.com", "sub", net.ParseIP("127.0.0.1"), 60, 0, false)
+		if err == nil {
+			t.Error("Expected error, got nil")
+		}
+	}
+}
+
+func testUpdateRecordAPISuccess() func(*testing.T) {
+	return func(t *testing.T) {
+		api := &MockIonosAPI{
+			SetARecordFunc: func(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+				return &common.ARecord{
+					Domain:   "sub",
+					IP:       "127.0.0.1",
+					TTL:      60,
+					Prio:     0,
+					Disabled: false,
+				}, nil
+			},
+		}
+
+		provider := ionosDnsProvider.IONOS{
+			API: api,
+		}
+
+		record, err := provider.UpdateRecord("example.com", "sub", net.ParseIP("127.0.0.1"), 60, 0, false)
+		if err != nil {
+			t.Errorf("Expected nil, got %v", err)
+		}
+
+		if record.Domain != "sub" {
+			t.Errorf("Expected sub, got %s", record.Domain)
+		}
+
+		if record.IP != "127.0.0.1" {
+			t.Errorf("Expected 127.0.0.1, got %s", record.IP)
+		}
+
+		if record.TTL != 60 {
+			t.Errorf("Expected 60, got %d", record.TTL)
+		}
+
+		if record.Prio != 0 {
+			t.Errorf("Expected 0, got %d", record.Prio)
+		}
+
+		if record.Disabled {
+			t.Error("Expected false, got true")
+		}
+	}
+}
+
+func TestGetRecord(t *testing.T) {
+	t.Run("API error", testGetRecordAPIError())
+	t.Run("API success", testGetRecordAPISuccess())
+}
+
+func testGetRecordAPIError() func(*testing.T) {
+	return func(t *testing.T) {
+		api := &MockIonosAPI{
+			GetARecordFunc: func(tld string, subdomain string) (*common.ARecord, error) {
+				return nil, errors.New("API error")
+			},
+		}
+
+		provider := ionosDnsProvider.IONOS{
+			API: api,
+		}
+
+		_, err := provider.GetRecord("example.com", "sub")
+		if err == nil {
+			t.Error("Expected error, got nil")
+		}
+	}
+}
+
+func testGetRecordAPISuccess() func(*testing.T) {
+	return func(t *testing.T) {
+		api := &MockIonosAPI{
+			GetARecordFunc: func(tld string, subdomain string) (*common.ARecord, error) {
+				return &common.ARecord{
+					Domain:   "sub",
+					IP:       "127.0.0.1",
+					TTL:      60,
+					Prio:     0,
+					Disabled: false,
+				}, nil
+			},
+		}
+
+		provider := ionosDnsProvider.IONOS{
+			API: api,
+		}
+
+		record, err := provider.GetRecord("example.com", "sub")
+		if err != nil {
+			t.Errorf("expected nil, got %v", err)
+		}
+
+		if record.Domain != "sub" {
+			t.Errorf("expected sub, got %s", record.Domain)
+		}
+
+		if record.IP != "127.0.0.1" {
+			t.Errorf("expected 127.0.0.1, got %s", record.IP)
+		}
+
+		if record.TTL != 60 {
+			t.Errorf("expected 60, got %d", record.TTL)
+		}
+
+		if record.Prio != 0 {
+			t.Errorf("expected 0, got %d", record.Prio)
+		}
+
+		if record.Disabled {
+			t.Error("expected false, got true")
+		}
+	}
+}

pkg/externalIpProvider/externalIpProvider.go

@@ -0,0 +1,9 @@
+package externalIpProvider
+
+import (
+	"net"
+)
+
+type ExternalIpProvider interface {
+	GetExternalIp() (net.IP, error)
+}

pkg/externalIpProvider/plain/plain.go

@@ -0,0 +1,56 @@
+package externalIpProvider
+
+import (
+	"errors"
+	"net"
+	"net/http"
+	"net/url"
+	externalIpProvider "realdnydns/pkg/externalIpProvider"
+)
+
+type ExternalIpProviderImplPlain struct {
+	IPProviderURL string
+	HTTPClient    *http.Client
+}
+
+type PlainExternalIpProviderConfig struct {
+	Url string `yaml:"url"`
+}
+
+func New(config PlainExternalIpProviderConfig) (externalIpProvider.ExternalIpProvider, error) {
+	if config.Url == "" {
+		return nil, errors.New("url is required")
+	}
+
+	return &ExternalIpProviderImplPlain{
+		config.Url,
+		&http.Client{},
+	}, nil
+}
+
+func (p *ExternalIpProviderImplPlain) GetExternalIp() (net.IP, error) {
+	parsedUrl, err := url.Parse(p.IPProviderURL)
+	if err != nil {
+		return nil, err
+	}
+
+	res, err := p.HTTPClient.Get(parsedUrl.String())
+	if err != nil {
+		return nil, err
+	}
+
+	if res.StatusCode != 200 {
+		return nil, errors.New("unexpected status code")
+	}
+
+	responseBody := make([]byte, res.ContentLength)
+	res.Body.Read(responseBody)
+	defer res.Body.Close()
+
+	parsedIp := net.ParseIP(string(responseBody))
+	if parsedIp == nil {
+		return nil, errors.New("unable to parse ip")
+	}
+
+	return parsedIp, nil
+}

pkg/externalIpProvider/plain/plain_test.go

@@ -0,0 +1,150 @@
+package externalIpProvider
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	t.Run("returns external ip provider", testNew())
+	t.Run("returns error when url is empty", testNewEmptyUrl())
+}
+
+func testNew() func(t *testing.T) {
+	return func(t *testing.T) {
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: "http://localhost",
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		if provider == nil {
+			t.Fatalf("NewPlain() returned nil provider")
+		}
+	}
+}
+
+func testNewEmptyUrl() func(t *testing.T) {
+	return func(t *testing.T) {
+		_, err := New(PlainExternalIpProviderConfig{})
+		if err == nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+	}
+}
+
+func TestGetExternal(t *testing.T) {
+	t.Run("returns external ip", testGetExternalIp())
+	t.Run("returns error when unable to parse ip", testGetExternalIpUnparsableIp())
+	t.Run("returns error when unexpected status code", testGetExternalIpUnexpectedStatusCode())
+	t.Run("returns error when unable to parse url", testGetExternalIpUnableToParseUrl())
+	t.Run("returns error when unable to get", testGetExternalIpUnableToGet())
+}
+
+func testGetExternalIp() func(t *testing.T) {
+	return func(t *testing.T) {
+		mockServer := httptest.NewServer(http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				w.Write([]byte("127.0.0.1"))
+			},
+		))
+		defer mockServer.Close()
+
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: mockServer.URL,
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		ip, err := provider.GetExternalIp()
+		if err != nil {
+			t.Fatalf("GetExternalIp() returned unexpected error: %v", err)
+		}
+
+		if ip.String() != "127.0.0.1" {
+			t.Fatalf("GetExternalIp() returned unexpected ip: %v instead of 127.0.0.1", ip)
+		}
+	}
+}
+
+func testGetExternalIpUnparsableIp() func(t *testing.T) {
+	return func(t *testing.T) {
+		mockServer := httptest.NewServer(http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				w.Write([]byte("not an ip"))
+			},
+		))
+		defer mockServer.Close()
+
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: mockServer.URL,
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		_, err = provider.GetExternalIp()
+		if err == nil {
+			t.Fatalf("GetExternalIp() returned unexpected error: %v", err)
+		}
+	}
+}
+
+func testGetExternalIpUnexpectedStatusCode() func(t *testing.T) {
+	return func(t *testing.T) {
+		mockServer := httptest.NewServer(http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(500)
+			},
+		))
+		defer mockServer.Close()
+
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: mockServer.URL,
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		_, err = provider.GetExternalIp()
+		if err == nil {
+			t.Fatalf("GetExternalIp() returned unexpected error: %v", err)
+		}
+	}
+}
+
+func testGetExternalIpUnableToParseUrl() func(t *testing.T) {
+	return func(t *testing.T) {
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: "not a url !'§%&",
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		_, err = provider.GetExternalIp()
+		if err == nil {
+			t.Fatalf("GetExternalIp() returned unexpected error: %v", err)
+		}
+	}
+}
+
+func testGetExternalIpUnableToGet() func(t *testing.T) {
+	return func(t *testing.T) {
+		// force error by using a non-responding url, beware of side effects
+		provider, err := New(PlainExternalIpProviderConfig{
+			Url: "http://localhost:1234",
+		})
+		if err != nil {
+			t.Fatalf("NewPlain() returned unexpected error: %v", err)
+		}
+
+		_, err = provider.GetExternalIp()
+		if err == nil {
+			t.Fatalf("GetExternalIp() returned unexpected error: %v", err)
+		}
+	}
+}

pkg/notificationProvider/console/console.go

@@ -0,0 +1,16 @@
+package notificationProviderConsole
+
+import (
+	"fmt"
+)
+
+type NotificationProviderImplConsole struct{}
+
+func New() *NotificationProviderImplConsole {
+	return &NotificationProviderImplConsole{}
+}
+
+func (p *NotificationProviderImplConsole) SendNotification(title string, message string) error {
+	fmt.Printf("%s: %s\n", title, message)
+	return nil
+}

pkg/notificationProvider/gotify/gotify.go

@@ -0,0 +1,89 @@
+package notificationProviderGotify
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+)
+
+type NotificationProviderImplGotifyConfig struct {
+	Url      string `yaml:"url"`
+	Token    string `yaml:"token"`
+	Priority int    `yaml:"priority"`
+}
+
+type NotificationProviderImplGotify struct {
+	Url        url.URL
+	Token      string
+	Priority   int
+	HTTPClient *http.Client
+}
+
+func New(config NotificationProviderImplGotifyConfig) (*NotificationProviderImplGotify, error) {
+	if config.Url == "" {
+		return nil, fmt.Errorf("url is required")
+	}
+
+	url, err := url.Parse(config.Url)
+	if err != nil {
+		return nil, err
+	}
+
+	if config.Token == "" {
+		return nil, fmt.Errorf("token is required")
+	}
+
+	if config.Priority < 0 || config.Priority > 4 {
+		return nil, fmt.Errorf("priority must be between 0 and 4")
+	}
+
+	return &NotificationProviderImplGotify{
+		*url,
+		config.Token,
+		config.Priority,
+		&http.Client{},
+	}, nil
+}
+
+func (p *NotificationProviderImplGotify) SendNotification(title string, message string) error {
+	type GotifyMessage struct {
+		Message  string `json:"message"`
+		Title    string `json:"title"`
+		Priority int    `json:"priority"`
+	}
+
+	messageJson, err := json.Marshal(GotifyMessage{
+		message,
+		title,
+		p.Priority,
+	})
+	if err != nil {
+		return err
+	}
+
+	messageUrl := p.Url
+	messageUrl = *messageUrl.JoinPath("message")
+	queryParams := messageUrl.Query()
+	queryParams.Add("token", p.Token)
+	messageUrl.RawQuery = queryParams.Encode()
+
+	req, err := http.NewRequest("POST", messageUrl.String(), bytes.NewBuffer(messageJson))
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", "application/json")
+
+	res, err := p.HTTPClient.Do(req)
+	if err != nil {
+		return err
+	}
+
+	if res.StatusCode != 200 {
+		return fmt.Errorf("unexpected status code: %d", res.StatusCode)
+	}
+
+	return nil
+}

pkg/notificationProvider/gotify/gotify_test.go

@@ -0,0 +1,81 @@
+package notificationProviderGotify_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	gotify "realdnydns/pkg/notificationProvider/gotify"
+)
+
+func TestNew(t *testing.T) {
+	t.Run("URL is required", testNewEmptyUrl())
+	t.Run("Token is required", testNewEmptyToken())
+	t.Run("Priority must be between 0 and 4", testNewInvalidPriority())
+	t.Run("Sends POST request to url", testNewSendsPostRequest())
+}
+
+func testNewEmptyUrl() func(t *testing.T) {
+	return func(t *testing.T) {
+		_, err := gotify.New(gotify.NotificationProviderImplGotifyConfig{
+			Token:    "1234",
+			Priority: 1,
+		})
+
+		if err.Error() != "url is required" {
+			t.Errorf("Expected error 'url is required', got %v", err)
+		}
+	}
+}
+
+func testNewEmptyToken() func(t *testing.T) {
+	return func(t *testing.T) {
+		_, err := gotify.New(gotify.NotificationProviderImplGotifyConfig{
+			Url:      "http://localhost:1234",
+			Priority: 0,
+		})
+
+		if err.Error() != "token is required" {
+			t.Errorf("Expected error 'token is required', got %v", err)
+		}
+	}
+}
+
+func testNewInvalidPriority() func(t *testing.T) {
+	return func(t *testing.T) {
+		_, err := gotify.New(gotify.NotificationProviderImplGotifyConfig{
+			Url:      "http://localhost:1234",
+			Token:    "token",
+			Priority: 5,
+		})
+
+		if err.Error() != "priority must be between 0 and 4" {
+			t.Errorf("Expected error 'priority must be between 0 and 4', got %v", err)
+		}
+	}
+}
+
+func testNewSendsPostRequest() func(t *testing.T) {
+	return func(t *testing.T) {
+		mockServer := httptest.NewServer(http.HandlerFunc(
+			func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(200)
+			},
+		))
+		defer mockServer.Close()
+
+		provider, err := gotify.New(gotify.NotificationProviderImplGotifyConfig{
+			Url:      mockServer.URL,
+			Token:    "1234",
+			Priority: 0,
+		})
+		if err != nil {
+			t.Fatalf("New() returned unexpected error: %v", err)
+		}
+
+		err = provider.SendNotification("title", "message")
+		if err != nil {
+			t.Fatalf("SendNotification() returned unexpected error: %v", err)
+		}
+	}
+}

pkg/notificationProvider/notificationProvider.go

@@ -0,0 +1,5 @@
+package notificationProvider
+
+type NotificationProvider interface {
+	SendNotification(title string, message string) error
+}

pkg/realDynDns/realDynDns.go

@@ -0,0 +1,152 @@
+package realDynDns
+
+import (
+	"fmt"
+	"log/slog"
+	"sync"
+	"time"
+
+	"realdnydns/pkg/config"
+	"realdnydns/pkg/dnsProvider"
+	"realdnydns/pkg/externalIpProvider"
+	"realdnydns/pkg/notificationProvider"
+
+	"github.com/go-co-op/gocron"
+)
+
+type ChangeDetector struct {
+	externalIpProvider   externalIpProvider.ExternalIpProvider
+	dnsProvider          dnsProvider.DNSProvider
+	notificationProvider notificationProvider.NotificationProvider
+	domains              []config.DomainConfig
+	logger               *slog.Logger
+}
+
+func New(
+	externalIpProvider externalIpProvider.ExternalIpProvider,
+	dnsProvider dnsProvider.DNSProvider,
+	notificationProvider notificationProvider.NotificationProvider,
+	domains []config.DomainConfig,
+	logger *slog.Logger,
+) ChangeDetector {
+	return ChangeDetector{
+		externalIpProvider:   externalIpProvider,
+		dnsProvider:          dnsProvider,
+		notificationProvider: notificationProvider,
+		domains:              domains,
+		logger:               logger,
+	}
+}
+
+func (c *ChangeDetector) RunWithSchedule(checkInterval string) (*gocron.Scheduler, *gocron.Job, error) {
+	s := gocron.NewScheduler(time.UTC)
+	s.SingletonMode()
+	s.CronWithSeconds(checkInterval)
+
+	job, err := s.DoWithJobDetails(func(job gocron.Job) {
+		numberChanged, err := c.detectAndApplyChanges()
+		if err != nil {
+			panic(err)
+		}
+		fmt.Printf("Number of changes: %d\n", numberChanged)
+		fmt.Println("Next run:", job.NextRun())
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return s, job, nil
+}
+
+func (c *ChangeDetector) RunOnce() (int, error) {
+	return c.detectAndApplyChanges()
+}
+
+func (c *ChangeDetector) detectAndApplyChanges() (int, error) {
+	c.logger.Info("Detecting and applying changes")
+
+	externalIp, err := c.externalIpProvider.GetExternalIp()
+	if err != nil {
+		c.logger.Error("Failed to retrieve external IP", slog.String("error", err.Error()))
+		return 0, err
+	}
+
+	var wg sync.WaitGroup
+
+	numberUpdatedChannel := make(chan int)
+
+	for _, domain := range c.domains {
+		for _, subdomain := range domain.Subdomains {
+			wg.Add(1)
+
+			go func(domain config.DomainConfig, subdomain string) {
+				defer wg.Done()
+
+				c.logger.Info("Checking record",
+					slog.String("tld", domain.TLD),
+					slog.String("subdomain", subdomain),
+				)
+				currentRecord, err := c.dnsProvider.GetRecord(domain.TLD, subdomain)
+				if err != nil {
+					c.logger.Error("Failed to retrieve record",
+						slog.String("error", err.Error()),
+						slog.String("tld", domain.TLD),
+						slog.String("subdomain", subdomain),
+					)
+					return
+				}
+
+				if currentRecord.IP != externalIp.String() {
+					c.logger.Info("Record has changed",
+						slog.String("tld", domain.TLD),
+						slog.String("subdomain", subdomain),
+						slog.String("current_ip", currentRecord.IP),
+						slog.String("external_ip", externalIp.String()),
+					)
+
+					err = c.notificationProvider.SendNotification(
+						fmt.Sprintf("Update %s.%s", subdomain, domain.TLD),
+						fmt.Sprintf("The IP of %s has changed from %s to %s", domain.TLD, currentRecord.IP, externalIp.String()),
+					)
+					if err != nil {
+						c.logger.Warn("Failed to send notification",
+							slog.String("error", err.Error()),
+						)
+						return
+					}
+
+					c.logger.Info("Updating record",
+						slog.String("tld", domain.TLD),
+						slog.String("subdomain", subdomain),
+						slog.String("current_ip", currentRecord.IP),
+						slog.String("external_ip", externalIp.String()),
+					)
+					_, err = c.dnsProvider.UpdateRecord(domain.TLD, subdomain, externalIp, currentRecord.TTL, currentRecord.Prio, currentRecord.Disabled)
+					if err != nil {
+						c.logger.Error("Failed to update record",
+							slog.String("error", err.Error()),
+							slog.String("tld", domain.TLD),
+							slog.String("subdomain", subdomain),
+						)
+						return
+					}
+
+					numberUpdatedChannel <- 1
+				}
+			}(domain, subdomain)
+		}
+	}
+
+	go func() {
+		wg.Wait()
+		close(numberUpdatedChannel)
+	}()
+
+	numberUpdated := 0
+	for v := range numberUpdatedChannel {
+		numberUpdated += v
+	}
+
+	c.logger.Info("Run completed", slog.Int("number_of_changes", numberUpdated))
+	return numberUpdated, nil
+}

pkg/realDynDns/realDynDns_test.go

@@ -0,0 +1,120 @@
+package realDynDns
+
+import (
+	"log/slog"
+	"net"
+	"realdnydns/model/common"
+	"realdnydns/pkg/config"
+	"testing"
+)
+
+type MockExternalIpProvider struct {
+	ExternalIp string
+}
+
+func (m *MockExternalIpProvider) GetExternalIp() (net.IP, error) {
+	return net.ParseIP(m.ExternalIp), nil
+}
+
+type MockDNSProvider interface {
+	UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error)
+	GetRecord(tld string, subdomain string) (*common.ARecord, error)
+}
+
+type MockDNSProviderImpl struct {
+	GetRecordIpResponse    string
+	UpdateRecordIpResponse string
+}
+
+func (m *MockDNSProviderImpl) GetRecord(tld string, subdomain string) (*common.ARecord, error) {
+	return &common.ARecord{
+		IP:       m.GetRecordIpResponse,
+		TTL:      10,
+		Prio:     20,
+		Disabled: false,
+	}, nil
+}
+
+func (m *MockDNSProviderImpl) UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+	return &common.ARecord{
+		IP:       m.UpdateRecordIpResponse,
+		TTL:      10,
+		Prio:     20,
+		Disabled: false,
+	}, nil
+}
+
+type MockedNotificationProvider struct{}
+
+type MockedNotificationProviderImpl struct{}
+
+func (m *MockedNotificationProviderImpl) SendNotification(title string, message string) error {
+	return nil
+}
+
+func TestDetectAndApplyChanges(t *testing.T) {
+	t.Run("with changes", testDetectAndApplyChangesWithChanges())
+	t.Run("without changes", testDetectAndApplyChangesWithoutChanges())
+}
+
+func testDetectAndApplyChangesWithChanges() func(t *testing.T) {
+	return func(t *testing.T) {
+		changeDetector := New(&MockExternalIpProvider{
+			ExternalIp: "127.0.0.1",
+		}, &MockDNSProviderImpl{
+			GetRecordIpResponse:    "127.0.0.2",
+			UpdateRecordIpResponse: "127.0.0.1",
+		}, &MockedNotificationProviderImpl{},
+			[]config.DomainConfig{
+				{
+					TLD: "example.com",
+					Subdomains: []string{
+						"test",
+						"@",
+					},
+				},
+			},
+			slog.Default(),
+		)
+
+		numberUpdated, err := changeDetector.RunOnce()
+		if err != nil {
+			t.Errorf("expected no error, got %v", err)
+		}
+
+		if numberUpdated != 2 {
+			t.Errorf("expected numberUpdated to be 2, got %v", numberUpdated)
+		}
+	}
+}
+
+func testDetectAndApplyChangesWithoutChanges() func(t *testing.T) {
+	return func(t *testing.T) {
+		changeDetector := New(&MockExternalIpProvider{
+			ExternalIp: "127.0.0.1",
+		}, &MockDNSProviderImpl{
+			GetRecordIpResponse:    "127.0.0.1",
+			UpdateRecordIpResponse: "127.0.0.1",
+		}, &MockedNotificationProviderImpl{},
+			[]config.DomainConfig{
+				{
+					TLD: "example.com",
+					Subdomains: []string{
+						"test",
+						"@",
+					},
+				},
+			},
+			slog.Default(),
+		)
+
+		numberUpdated, err := changeDetector.RunOnce()
+		if err != nil {
+			t.Errorf("expected no error, got %v", err)
+		}
+
+		if numberUpdated != 0 {
+			t.Errorf("expected numberUpdated to be 0, got %v", numberUpdated)
+		}
+	}
+}