docs(get-images-from-files): document compose support (#28)

get-images-from-files already supports compose files. This PR explicitly documents the compatibility and includes a test.

Reviewed-on: t.behrendt/trivy-actions#28
Reviewed-by: branch-buddy <branch-buddy@t00n.de>
Co-authored-by: t.behrendt <t.behrendt@t00n.de>
Co-committed-by: t.behrendt <t.behrendt@t00n.de>

get-images-from-files/README.md

@@ -2,7 +2,7 @@
 
 A reusable Gitea Action, that extracts docker images from selected files in a repository.
 
-The action supports Dockerfiles and Kubernetes manifests. Other files are supported if they have a recognizable image reference. Duplicate image references are deduplicated.
+The action supports Dockerfiles, Kubernetes manifests, and Docker Compose/compose files. Other files are supported if they have a recognizable image reference. Duplicate image references are deduplicated.
 
 **Note:** Only fully-qualified refs (with registry, e.g. `docker.io/library/alpine:latest`, `gcr.io/distroless/static:nonroot@sha256:...`) are included; short refs like `alpine:latest` are omitted as their use is discouraged.
 
@@ -17,6 +17,7 @@ The action supports Dockerfiles and Kubernetes manifests. Other files are suppor
     files: |
         - Dockerfile
         - k8s/50_deployment.yaml
+        - dockers/compose.yaml
         - values/traefik.yaml
 ```
 
@@ -37,6 +38,7 @@ jobs:
             files: |
               - Dockerfile
               - k8s/50_deployment.yaml
+              - dockers/compose.yaml
               - values/traefik.yaml
 ```
 

get-images-from-files/action.yaml

@@ -1,5 +1,5 @@
 name: "Get Images From Files"
-description: "Extract docker images from selected files (Dockerfiles, Kubernetes manifests, and files with recognizable image references)"
+description: "Extract docker images from selected files (Dockerfiles, Kubernetes manifests, Docker Compose/compose files, and files with recognizable image references)"
 author: "Timo Behrendt <t.behrendt@t00n.de>"
 branding:
   icon: "package"
@@ -30,7 +30,7 @@ runs:
             [ -f "$f" ] || continue
             # Dockerfile: FROM [--platform=...] <image>
             awk '/^[[:space:]]*FROM[[:space:]]/ { print $NF }' "$f" 2>/dev/null || true
-            # Kubernetes / Compose: image: <ref>
+            # Kubernetes / Docker Compose: image: <ref>
             grep -E '[[:space:]]image:[[:space:]]' "$f" 2>/dev/null | sed 's/.*image:[[:space:]]*//' | awk '{ print $1 }' || true
           done | grep -E '/' | sort -u | paste -sd,
         )

get-images-from-files/test-compose.yaml

@@ -0,0 +1,6 @@
+# Used by CI to test get-images-from-files action (Docker Compose, registry refs only)
+services:
+  web:
+    image: example.com/compose/web:v3
+  worker:
+    image: example.com/compose/worker:v3