i try

.woodpecker/alertmanager-ntfy.yaml

@@ -0,0 +1,52 @@
+# Manually set a workspace path, so we can use it literally, without using
+# ${CI_WORKSPACE}, when running kaniko, since using ${CI_WORKSPACE} doesn't work.
+# https://github.com/woodpecker-ci/woodpecker/issues/3982
+workspace:
+  path: src
+
+matrix:
+  ALERTMANAGER_NTFY_VERSION:
+    - 76d5f772f70d6915c89da00414c20009b03cc361
+  IMAGE_NAME:
+    - git.hamburg.ccc.de/ccchh/oci-images/alertmanager-ntfy
+
+steps:
+  - name: setup
+    image: alpine
+    commands:
+      - apk -u add git
+      - mkdir /woodpecker/images
+      - git clone --revision=${ALERTMANAGER_NTFY_VERSION} https://github.com/alexbakker/alertmanager-ntfy.git
+      - ls
+
+  - name: build-image
+    image: gcr.io/kaniko-project/executor
+    entrypoint:
+      - /kaniko/executor
+      - --context=dir:///woodpecker/src/alertmanager-ntfy
+      - --dockerfile=./Containerfile
+      - --destination=${IMAGE_NAME}:${ALERTMANAGER-NTFY_VERSION}
+      - --no-push
+      - --tar-path=/woodpecker/images/alertmanager-ntfy.tar
+
+#  - name: publish-image
+#    image: alpine
+#    environment:
+#      GIT_API_TOKEN:
+#        from_secret: GIT_API_TOKEN
+#    commands:
+#      - apk -u add crane
+#      - crane auth login git.hamburg.ccc.de -u woodpecker -p $GIT_API_TOKEN
+#      - crane push /woodpecker/images/keycloak.tar $IMAGE_NAME:$ALERTMANAGER-NTFY_VERSION-$CI_COMMIT_BRANCH
+#
+#  - name: tag-version
+#    image: alpine
+#    when:
+#      - branch: main
+#    environment:
+#      GIT_API_TOKEN:
+#        from_secret: GIT_API_TOKEN
+#    commands:
+#      - apk -u add crane
+#      - crane auth login git.hamburg.ccc.de -u woodpecker -p $GIT_API_TOKEN
+#      - crane tag $IMAGE_NAME:$ALERTMANAGER-NTFY_VERSION-$CI_COMMIT_BRANCH $ALERTMANAGER-NTFY_VERSION

alertmanager-ntfy/Containerfile

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+ARG TAG=latest
+FROM docker.io/golang:${TAG} as builder
+ARG CGO_ENABLED=0
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+
+RUN go build
+
+FROM scratch
+COPY --from=builder /app/alertmanager-ntfy /alertmanager-ntfy
+ENTRYPOINT ["/alertmanager-ntfy"]