readme

README.md

@@ -0,0 +1,22 @@
+# get-image-env-var
+Github/Gitea action used to get a docker image environment variable
+```yml
+name: echo env var
+on: [push]
+
+jobs:
+  get-env:
+    runs-on: ubuntu-latest
+    container:
+      image: catthehacker/ubuntu:act-latest
+    steps:
+      - name: get env var
+        id: getenv
+        uses: https://gitea.ar2000.me/ar2000/get-image-env-var@v2
+        with:
+          name: NEXTCLOUD_VERSION
+          image: nextcloud:latest
+      - name: echo
+        run: echo ${{steps.getenv.outputs.value}}
+```
+If you get a docker not found error make sure you are using the `catthehacker/ubuntu:act-latest` image as your job's container.

action.yml

@@ -19,17 +19,26 @@ inputs:
 outputs:
   value:
     description: "The environement variable's value"
-    value: ${{steps.worker.outputs.value}}
+    value: ${{steps.extract-value.outputs.value}}
 
 runs:
   using: composite
   steps:
-    - name: worker
-      id: worker
-      uses: addnab/docker-run-action@v3
+    - name: login
+      if: inputs.username != ''
+      uses: docker/login-action@v3
       with:
-        image: ${{inputs.image}}
-        registry: ${{inputs.registry}}
-        username: ${{inputs.username}}
-        password: ${{inputs.password}}
-        run: echo "::set-output name=value::${${{inputs.name}}}"
+        registry: ${{ inputs.registry}}
+        username: ${{ inputs.username }}
+        password: ${{ inputs.password }}
+    - name: Pull Docker image
+      shell: sh
+      run: docker pull ${{inputs.image}}
+    - name: Get variable value
+      id: extract-value
+      run: |
+        version=$(docker image inspect ${{inputs.image}} --format='{{range .Config.Env}}{{println .}}{{end}}' | grep ^${{inputs.name}}= | cut -d'=' -f2)
+        echo "${{inputs.name}}=$version"
+        echo "::set-output name=value::$version"
+      shell: bash
+