Introduce multiarch short alias tag (#427)

Before:

* No version specific tag which is no need to follow internal
  version up.
  e.g. from v1.18-debian-1.0 to v1.18-debian-1.1, pulling v1.18-debian is enough.

After:

Introduce short alias tag which is no need to follow
internal version up.

* v1.18-debian
* v1.18.0-debian

Signed-off-by: Kentaro Hayashi <[email protected]>

Author: kenhys

.github/workflows/docker-build.yml

@@ -195,6 +195,12 @@ jobs:
               ${{ env.REPOSITORY }}:${AMD64TAG} \
               ${{ env.REPOSITORY }}:${ARM64TAG} \
               ${{ env.REPOSITORY }}:${ARMHFTAG}
+            # v1.xx.y-debian (short alias without -1.x suffix)
+            MULTIARCH_SHORT_ALIAS=$(echo ${MULTIARCH_AMD64_TAG} | cut -d'-' -f1,2)
+            docker buildx imagetools create -t ${{ env.REPOSITORY }}:${MULTIARCH_SHORT_ALIAS} \
+              ${{ env.REPOSITORY }}:${AMD64TAG} \
+              ${{ env.REPOSITORY }}:${ARM64TAG} \
+              ${{ env.REPOSITORY }}:${ARMHFTAG}
           fi
           # v1.xx-debian-n.m
           if [ ${MULTIARCH_AMD64_SHORT_TAG} != ${MULTIARCH_ARM64_SHORT_TAG} -o ${MULTIARCH_AMD64_SHORT_TAG} != ${MULTIARCH_ARMHF_SHORT_TAG} -o ${MULTIARCH_ARM64_SHORT_TAG} != ${MULTIARCH_ARMHF_SHORT_TAG} ]; then
@@ -204,6 +210,12 @@ jobs:
               ${{ env.REPOSITORY }}:${SHORT_AMD64TAG} \
               ${{ env.REPOSITORY }}:${SHORT_ARM64TAG} \
               ${{ env.REPOSITORY }}:${SHORT_ARMHFTAG}
+            # v1.xx-debian (short alias without -1 suffix)
+            MULTIARCH_SHORT_ALIAS=$(echo ${MULTIARCH_AMD64_SHORT_TAG} | cut -d'-' -f1,2)
+            docker buildx imagetools create -t ${{ env.REPOSITORY }}:${MULTIARCH_SHORT_ALIAS} \
+              ${{ env.REPOSITORY }}:${SHORT_AMD64TAG} \
+              ${{ env.REPOSITORY }}:${SHORT_ARM64TAG} \
+              ${{ env.REPOSITORY }}:${SHORT_ARMHFTAG}
           fi
           # edge-debian
           docker buildx imagetools create -t ${{ env.REPOSITORY }}:edge-debian \