build: use raw instead of match for stable tag metadata (#2251)

Author: itzg

.github/workflows/build-multiarch.yml

@@ -125,16 +125,16 @@ jobs:
             type=ref,event=tag,enable=${{ matrix.variant == env.MAIN_VARIANT }}
             # and each variant (including main one) gets the tag with the variant suffix, such as 2023.1.1-java17
             type=ref,event=tag,suffix=-${{ matrix.variant }}
-            # latest repo tag gets a moving 'stable' image tag applied to the main variant
-            type=match,value=stable,enable=${{ matrix.variant == env.MAIN_VARIANT }},pattern=\d+\.\d+\.\d+
             # for building test/* branch images
-            type=ref,event=branch,suffix=-${{ matrix.variant }},enable=${{ github.ref_name != 'master' }}
-            # 
-            type=raw,value=${{ matrix.variant }},enable=${{ github.ref_name == 'master' }}
+            type=ref,event=branch,suffix=-${{ matrix.variant }},enable=${{ github.ref_name != github.event.repository.default_branch }}
+            # latest repo tag gets a moving 'stable' image tag applied to the main variant
+            type=raw,value=stable,enable=${{ github.ref_type == 'tag' && matrix.variant == env.MAIN_VARIANT }}            
+            # apply the variant as a moving tag for most recent commit per variant
+            type=raw,value=${{ matrix.variant }},enable=${{ github.ref_name == github.event.repository.default_branch }}
           # NOTE this identifies which variant will be published as "latest", which isn't
           # necessarily the newest version of Java
           flavor: |
-            latest=${{ matrix.variant == env.MAIN_VARIANT && github.ref_name == 'master' }}
+            latest=${{ matrix.variant == env.MAIN_VARIANT && github.ref_name == github.event.repository.default_branch }}
           labels: |
             org.opencontainers.image.authors=Geoff Bourne <itzgeoff@gmail.com>
 
@@ -191,7 +191,7 @@ jobs:
           push: >
             ${{ 
             github.ref_type == 'tag' 
-            || github.ref_name == 'master'
+            || github.ref_name == github.event.repository.default_branch
             || startsWith(github.ref_name, 'test/')
             || ( github.event_name == 'pull_request' 
                  && env.HAS_IMAGE_REPO_ACCESS