add registry as env variable

Author: nickspizzas

Diff for: .github/workflows/docker-publish.yml

@@ -15,6 +15,7 @@ on:
 
 env:
   IMAGE_NAME: helm-yaml
+  REGISTRY: ghcr.io
 
 jobs:
   # Run tests.
@@ -52,7 +53,7 @@ jobs:
       - name: Prepare Docker Metadata
         id: meta
         run: |
-          IMAGE_ID=ghcr.io/${{ github.repository_owner }}/$IMAGE_NAME
+          IMAGE_ID=${{ env.REGISTRY }}/${{ github.repository_owner }}/$IMAGE_NAME
 
           # Change all uppercase to lowercase
           IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')
@@ -72,7 +73,7 @@ jobs:
       - name:  Log into registry ${{ env.REGISTRY }}
         uses: docker/login-action@v1
         with:
-          registry: ghcr.io
+          registry: ${{ env.REGISTRY }}
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}