Add IMAGE_DIGEST output to release job

Signed-off-by: Marco Franssen <marco.franssen@philips.com>

.github/workflows/ci.yaml

@@ -63,6 +63,8 @@ jobs:
   release:
     name: release
     needs: [build]
+    outputs:
+      container_digest: ${{ steps.container_digest.outputs.container_digest }}
     runs-on: ubuntu-20.04
 
     steps:
@@ -105,6 +107,11 @@ jobs:
           LDFLAGS: ${{ steps.release-vars.outputs.LDFLAGS }}
           GIT_HASH: ${{ steps.release-vars.outputs.GIT_HASH }}
 
+      - name: Get container digest
+        id: container_digest
+        if: startsWith(github.ref, 'refs/tags/')
+        run: echo "::set-output name=container_digest::$(make container-digest GITHUB_REF=${GITHUB_REF})"
+
       - name: Logout from Container registries
         if: ${{ always() }}
         run: |

Makefile

@@ -20,6 +20,9 @@ LDFLAGS="-X $(PKG).GitVersion=$(GIT_VERSION) -X $(PKG).gitCommit=$(GIT_HASH) -X
 GO_BUILD_FLAGS := -trimpath -ldflags $(LDFLAGS)
 COMMANDS       := slsa-provenance
 
+HUB_REPO := philipssoftware/slsa-provenance
+GHCR_REPO := ghcr.io/philips-labs/slsa-provenance
+
 check_defined = \
     $(strip $(foreach 1,$1, \
         $(call __check_defined,$1,$(strip $(value 2)))))
@@ -79,7 +82,10 @@ build: $(addprefix bin/,$(COMMANDS)) ## builds binaries
 image: ## build the binary in a docker image
 	docker build \
 		-t "philipssoftware/slsa-provenance:$(GIT_TAG)" \
-		-t "philipssoftware/slsa-provenance:$(GIT_HASH)" .
+		-t "philipssoftware/slsa-provenance:$(GIT_HASH)" \
+		-t "ghcr.io/philips-labs/slsa-provenance:$(GIT_TAG)" \
+		-t "ghcr.io/philips-labs/slsa-provenance:$(GIT_HASH)" \
+		.
 
 $(GO_PATH)/bin/goreleaser:
 	go install github.com/goreleaser/goreleaser@v0.182.1
@@ -119,3 +125,8 @@ gh-release: ## Creates a new release by creating a new tag and pushing it
 	@echo
 	@git stash pop
 
+.PHONY: container-digest
+container-digest: ## retrieves the container digest from the given tag
+	@:$(call check_defined, GITHUB_REF)
+	@docker inspect $(HUB_REPO):$(subst refs/tags/,,$(GITHUB_REF)) --format '{{ index .RepoDigests 0 }}' | cut -d '@' -f 2
+