validate authors target

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/validate.yml

@@ -20,6 +20,7 @@ jobs:
           - lint
           - shellcheck
           - validate-vendor
+          - update-authors # ensure authors update target runs fine
     steps:
       -
         name: Checkout

docker-bake.hcl

@@ -114,6 +114,20 @@ target "mod-outdated" {
     output = ["type=cacheonly"]
 }
 
+target "validate-authors" {
+    inherits = ["_common"]
+    dockerfile = "./dockerfiles/Dockerfile.authors"
+    target = "validate"
+    output = ["type=cacheonly"]
+}
+
+target "update-authors" {
+    inherits = ["_common"]
+    dockerfile = "./dockerfiles/Dockerfile.authors"
+    target = "update"
+    output = ["."]
+}
+
 target "test" {
     target = "test"
     output = ["type=cacheonly"]

docker.Makefile

@@ -97,7 +97,7 @@ mod-outdated: ## check outdated dependencies
 
 .PHONY: authors
 authors: ## generate AUTHORS file from git history
-	$(DOCKER_RUN) -it $(DEV_DOCKER_IMAGE_NAME) make authors
+	docker buildx bake update-authors
 
 .PHONY: manpages
 manpages: build_docker_image ## generate man pages from go source and markdown

dockerfiles/Dockerfile.authors

@@ -0,0 +1,23 @@
+# syntax=docker/dockerfile:1.3-labs
+
+FROM alpine:3.14 AS gen
+RUN apk add --no-cache bash git
+WORKDIR /src
+RUN --mount=type=bind,target=. \
+  mkdir /out && ./scripts/docs/generate-authors.sh /out
+
+FROM scratch AS update
+COPY --from=gen /out /
+
+FROM gen AS validate
+RUN --mount=type=bind,target=.,rw <<EOT
+set -e
+git add -A
+cp -rf /out/* .
+diff=$(git status --porcelain -- AUTHORS)
+if [ -n "$diff" ]; then
+  echo >&2 'ERROR: Authors result differs. Please update with "make -f docker.Makefile authors"'
+  echo "$diff"
+  exit 1
+fi
+EOT

scripts/docs/generate-authors.sh

@@ -1,10 +1,8 @@
 #!/usr/bin/env bash
 set -e
 
-cd "$(dirname "$(readlink -f "${BASH_SOURCE[*]}")")/../.."
-
 # see also ".mailmap" for how email addresses and names are deduplicated
-
+OUT="${1:-.}"
 {
 	cat <<-'EOH'
 	# This file lists all individuals having contributed content to the repository.
@@ -12,4 +10,5 @@ cd "$(dirname "$(readlink -f "${BASH_SOURCE[*]}")")/../.."
 	EOH
 	echo
 	git log --format='%aN <%aE>' | LC_ALL=C.UTF-8 sort -uf
-} > AUTHORS
+} > "$OUT/AUTHORS"
+cat "$OUT/AUTHORS"