Getting the github Repo from env (#1532)

.github/workflows/main.yml

@@ -2,20 +2,41 @@ name: Docker image CI
 
 on:
   push:
-    branches: ['master']
-  workflow_dispatch:
+    # takes muliple branch names
+    branches: 
+      - master
+      - '[0-9][0-9][0-9][0-9].[0-9][0-9].*' # 2021.01.01
+
+env:
+  IMAGE_TAG: latest
+  REPO_URL: ${{ github.repository }}
+
 jobs:
   build:
+    # to test a feature, change the repo name to your github id
+    if: github.repository_owner == 'tl-its-umich-edu'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+
+      - name: Checkout code 
+        uses: actions/checkout@v3
+
+      - name: Extract branch name
+        id: extract_branch
+        run: echo "BRANCH_NAME=$(basename ${{ github.ref }})" >> $GITHUB_ENV
+
+      - name: build Docker image
+        run: |
+          docker build . --tag ghcr.io/${{ env.REPO_URL }}:${{ env.IMAGE_TAG }}-${BRANCH_NAME}
+      
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v2
         with:
             registry: ghcr.io
             username: ${{ github.actor }}
             password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Build Docker Image
+
+      - name: Push Docker image to GitHub Container Registry
         run: |
-          docker build . --tag ghcr.io/tl-its-umich-edu/my-learning-analytics:latest
-          docker push ghcr.io/tl-its-umich-edu/my-learning-analytics:latest
+          docker push ghcr.io/${{ env.REPO_URL }}:${{ env.IMAGE_TAG }}-${BRANCH_NAME}
+