fix: add labels to OCI image

With this, we're being good OCI citizens (or something like that)
by telling people where to find the source for the image.

Plus, renovate uses the org.opencontainers.image.source label to
find the source for changelogs, so it will now also show changelogs.

Author: morremeyer

.goreleaser.yaml

@@ -43,3 +43,9 @@ dockers:
       - "ghcr.io/envelope-zero/backend:v{{ .Major }}"
       - "ghcr.io/envelope-zero/backend:v{{ .Major }}.{{ .Minor }}"
       - "ghcr.io/envelope-zero/backend:latest"
+
+    build_flag_templates:
+      - "--label=org.opencontainers.image.created={{.Date}}"
+      - "--label=org.opencontainers.image.revision={{.FullCommit}}"
+      - "--label=org.opencontainers.image.title={{.ProjectName}}"
+      - "--label=org.opencontainers.image.version={{.Version}}"

Dockerfile

@@ -16,3 +16,13 @@ FROM scratch
 WORKDIR /
 COPY --from=builder /app/backend /backend
 ENTRYPOINT ["/backend"]
+
+# Keep "maintainer" and "org.opencontainers.image.authors" in sync
+LABEL "maintainer"="Envelope Zero Maintainers <[email protected]>"
+LABEL "org.opencontainers.image.authors"="Envelope Zero Maintainers <[email protected]>"
+LABEL "org.opencontainers.image.description"="Backend for Envelope Zero"
+LABEL "org.opencontainers.image.documentation"="https://github.com/envelope-zero/backend"
+LABEL "org.opencontainers.image.licenses"="AGPL-3.0-or-later"
+LABEL "org.opencontainers.image.source"="https://github.com/envelope-zero/backend"
+LABEL "org.opencontainers.image.url"="https://github.com/envelope-zero/backend"
+LABEL "org.opencontainers.image.vendor"="Envelope Zero Maintainers"