build multiple flavors at the same time. handle tags for branches

.github/workflows/build.yaml

@@ -1,7 +1,7 @@
 name: Docker
 on:
   push:
-    branches: [ main, sandbox ]
+    branches: [ main, beta ]
     # Publish semver tags as releases.
     tags: [ 'v*.*.*' ]
 
@@ -21,7 +21,9 @@ jobs:
       contents: read
       packages: write
       id-token: write
-
+    strategy:
+      matrix:
+        flavor: [main, sandbox]
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2
@@ -45,10 +47,15 @@ jobs:
         uses: docker/metadata-action@v4
         with:
           flavor: |
-            latest=${{ github.event_name == 'push' && contains(github.ref, 'refs/tags/') }}
+            # only latest if push has a tag and we're building the "main" flavor
+            latest=${{ github.event_name == 'push' && matrix.flavor == 'main' && contains(github.ref, 'refs/tags/') }}
           tags: |
-            type=ref,enable=true,event=branch
-            type=ref,enable=true,event=tag
+            # if this is a tag'd build, prefix it with the flavor (eg. main-v1.2.3 and sandbox-v1.2.3)
+            type=ref,event=tag,prefix=${{ matrix.flavor }}-
+            # if this is a main branch build, just tag it with the flavor (eg. main and sandbox)
+            type=raw,value=${{ matrix.flavor }},enable=${{  github.ref_name == 'main' }}
+            # if this is a (non main) branch build, tag it with the flavor and branch name (eg. main-branch and sandbox-branch)
+            type=ref,event=branch,prefix=${{ matrix.flavor }}-,enable=${{ matrix.flavor != 'main' }}
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
       # Build and push Docker image with Buildx (don't push on PR)
       # https://github.com/docker/build-push-action
@@ -63,4 +70,4 @@ jobs:
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           build-args: |
-            FASTEN_ENV=${{ github.ref_name == 'sandbox' && 'sandbox' || 'prod' }}
+            FASTEN_ENV=${{ matrix.flavor == 'sandbox' && 'sandbox' || 'prod' }}