Dockerfile

@@ -0,0 +1,21 @@
+FROM golang:1.21-alpine
+
+# Set the Current Working Directory inside the container
+WORKDIR /app
+
+# Copy go mod and sum files
+COPY go.mod go.sum ./
+
+# Download all dependencies. Dependencies will be cached if the go.mod and go.sum files are not changed
+RUN go mod download
+
+# Copy the source from the current directory to the Working Directory inside the container
+COPY . .
+
+# Build the Go app
+RUN go build -o main .
+
+
+# Command to run the executable
+
+CMD ["./main"]

Makefile

@@ -0,0 +1,8 @@
+test:
+	go test ./pkg/... -coverprofile=coverage.out
+
+build:
+	go build
+
+lint:
+	golint ./...

README.md

@@ -1,2 +1,5 @@
 # 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.

config.example.yaml

@@ -0,0 +1,16 @@
+---
+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
+domains:
+  - tld: example.com
+    subdomains:
+      - "@"
+      - www
+check_interval: 0 0 0/6 * * * *

go.mod

@@ -0,0 +1,15 @@
+module realdnydns
+
+go 1.20
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-co-op/gocron v1.31.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/robfig/cron/v3 v3.0.1 // indirect
+	github.com/stretchr/objx v0.5.0 // indirect
+	github.com/stretchr/testify v1.8.4 // indirect
+	go.uber.org/atomic v1.9.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,40 @@
+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 v1.31.2 h1:tAUW64bxYc5QlzEy2t30TnHX2+uInNDajKXxWi4SACA=
+github.com/go-co-op/gocron v1.31.2/go.mod h1:39f6KNSGVOU1LO/ZOoZfcSxwlsJDQOKSu8erN0SH48Y=
+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/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/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=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
+github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/rogpeppe/go-internal v1.8.1/go.mod h1:JeRgkft04UBgHMgCIwADu4Pn6Mtm5d4nPKWu0nJ5d+o=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0 h1:1zr/of2m5FGMsad5YfcqgdqdWrIhu+EBEJRhR1U7z/c=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+go.uber.org/atomic v1.9.0 h1:ECmE8Bn/WFTYwEW/bpKD3M8VtR/zQVbavAoalC1PYyE=
+go.uber.org/atomic v1.9.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+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.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
+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=

model/common/common.go

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

pkg/changeDetector/changeDetector.go

@@ -0,0 +1,53 @@
+package changeDetector
+
+import (
+	"realdnydns/pkg/config"
+	"realdnydns/pkg/dnsProvider"
+	"realdnydns/pkg/externalIpProvider"
+)
+
+type ChangeDetector struct {
+	externalIpProvider externalIpProvider.ExternalIpProvider
+	dnsProvider        dnsProvider.DNSProvider
+	domains            []config.DomainConfig
+}
+
+func New(
+	externalIpProvider externalIpProvider.ExternalIpProvider,
+	dnsProvider dnsProvider.DNSProvider,
+	domains []config.DomainConfig,
+) ChangeDetector {
+	return ChangeDetector{
+		externalIpProvider: externalIpProvider,
+		dnsProvider:        dnsProvider,
+		domains:            domains,
+	}
+}
+
+func (c *ChangeDetector) DetectAndApplyChanges() (int, error) {
+	externalIp, err := c.externalIpProvider.GetExternalIp()
+	if err != nil {
+		return 0, err
+	}
+
+	var numberUpdated int
+
+	for _, domain := range c.domains {
+		for _, subdomain := range domain.Subdomains {
+			currentRecord, err := c.dnsProvider.GetRecord(domain.TLD, subdomain)
+			if err != nil {
+				return numberUpdated, err
+			}
+
+			if currentRecord.IP != externalIp.String() {
+				_, err = c.dnsProvider.UpdateRecord(domain.TLD, subdomain, externalIp, currentRecord.TTL, currentRecord.Prio, currentRecord.Disabled)
+				numberUpdated++
+				if err != nil {
+					return numberUpdated, err
+				}
+			}
+		}
+	}
+
+	return numberUpdated, nil
+}

pkg/changeDetector/changeDetector_test.go

@@ -0,0 +1,105 @@
+package changeDetector
+
+import (
+	"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
+}
+
+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",
+		}, []config.DomainConfig{
+			{
+				TLD: "example.com",
+				Subdomains: []string{
+					"test",
+					"@",
+				},
+			},
+		})
+
+		numberUpdated, err := changeDetector.DetectAndApplyChanges()
+		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",
+		}, []config.DomainConfig{
+			{
+				TLD: "example.com",
+				Subdomains: []string{
+					"test",
+					"@",
+				},
+			},
+		})
+
+		numberUpdated, err := changeDetector.DetectAndApplyChanges()
+		if err != nil {
+			t.Errorf("expected no error, got %v", err)
+		}
+
+		if numberUpdated != 0 {
+			t.Errorf("expected numberUpdated to be 0, got %v", numberUpdated)
+		}
+	}
+}

pkg/config/__mocks__/testLoadCanFindFile.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/config/config.go

@@ -0,0 +1,43 @@
+package config
+
+import (
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+type DomainConfig struct {
+	TLD        string   `yaml:"tld"`
+	Subdomains []string `yaml:"subdomains"`
+}
+
+type Config struct {
+	ExternalIPProvider ExternalIpProviderConfig `yaml:"ip_provider"`
+	DNSProvider        DNSProviderConfig        `yaml:"dns_provider"`
+	Domains            []DomainConfig           `yaml:"domains"`
+	CheckInterval      string                   `yaml:"check_interval"`
+}
+
+type ExternalIpProviderConfig struct {
+	Type           string    `yaml:"type"`
+	ProviderConfig yaml.Node `yaml:"config"`
+}
+
+type DNSProviderConfig struct {
+	Type           string    `yaml:"type"`
+	ProviderConfig yaml.Node `yaml:"config"`
+}
+
+func (c *Config) Load(filePath string) error {
+	err := yaml.Unmarshal([]byte(filePath), c)
+	if err != nil {
+		inputConfig, err := os.ReadFile(filePath)
+		if err != nil {
+			return err
+		}
+
+		return yaml.Unmarshal(inputConfig, c)
+	}
+
+	return err
+}

pkg/config/config_test.go

@@ -0,0 +1,65 @@
+package config
+
+import (
+	"testing"
+)
+
+func TestLoad(t *testing.T) {
+	t.Run("Can find file", testLoadCanFindFile())
+	t.Run("Cannot find file", testLoadCannotFindFile())
+	t.Run("Unmarshals from direct input", testLoadUnmarshalsFromDirectInput())
+}
+
+func testLoadCanFindFile() func(t *testing.T) {
+	return func(t *testing.T) {
+
+		c := Config{}
+		err := c.Load("./__mocks__/testLoadCanFindFile.yaml")
+
+		want := c.DNSProvider.Type == "ionos" && c.ExternalIPProvider.Type == "plain"
+
+		if !want || err != nil {
+			t.Fatalf("DnsProviderName couldn't be properly loaded or unmarshaled, Load() = %v, want %v", err, want)
+		}
+	}
+}
+
+func testLoadCannotFindFile() func(t *testing.T) {
+	return func(t *testing.T) {
+		c := Config{}
+		err := c.Load("nonexistent.yaml")
+		want := err != nil
+
+		if !want {
+			t.Fatalf("Config didn't throw an error")
+		}
+	}
+}
+
+func testLoadUnmarshalsFromDirectInput() func(t *testing.T) {
+	return func(t *testing.T) {
+		c := Config{}
+		err := c.Load(`---
+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 * * * *`)
+
+		want := c.DNSProvider.Type == "ionos" && c.ExternalIPProvider.Type == "plain"
+
+		if !want || err != nil {
+			t.Fatalf("DnsProviderName couldn't be properly loaded or unmarshaled, Load() = %v, want %v", err, want)
+		}
+	}
+}

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/externalIpProvider/externalIpProvider.go

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