hack: authors Dockerfile and bake target

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

Makefile

@@ -42,6 +42,10 @@ validate-shfmt:
 shfmt:
 	./hack/shfmt
 
+.PHONY: validate-authors
+validate-authors:
+	$(BUILDX_CMD) bake validate-authors
+
 .PHONY: validate-generated-files
 validate-generated-files:
 	./hack/validate-generated-files
@@ -60,3 +64,7 @@ vendor:
 .PHONY: generated-files
 generated-files:
 	./hack/update-generated-files
+
+.PHONY: authors
+authors:
+	$(BUILDX_CMD) bake authors

docker-bake.hcl

@@ -1,9 +1,14 @@
+variable "ALPINE_VERSION" {
+  default = null
+}
+
 variable "GO_VERSION" {
   default = null
 }
 
 target "_common" {
   args = {
+    ALPINE_VERSION = ALPINE_VERSION
     GO_VERSION = GO_VERSION
     BUILDKIT_CONTEXT_KEEP_GIT_DIR = 1
   }
@@ -20,9 +25,23 @@ target "validate-vendor" {
   output = ["type=cacheonly"]
 }
 
+target "validate-authors" {
+  inherits = ["_common"]
+  dockerfile = "./hack/dockerfiles/authors.Dockerfile"
+  target = "validate"
+  output = ["type=cacheonly"]
+}
+
 target "vendor" {
   inherits = ["_common"]
   dockerfile = "./hack/dockerfiles/vendor.Dockerfile"
   target = "update"
   output = ["."]
 }
+
+target "authors" {
+  inherits = ["_common"]
+  dockerfile = "./hack/dockerfiles/authors.Dockerfile"
+  target = "update"
+  output = ["."]
+}

hack/dockerfiles/authors.Dockerfile

@@ -0,0 +1,34 @@
+# syntax=docker/dockerfile-upstream:master
+
+ARG ALPINE_VERSION=3.17
+
+FROM alpine:${ALPINE_VERSION} AS gen
+RUN apk add --no-cache git
+WORKDIR /src
+RUN --mount=type=bind,target=. <<EOT
+  set -e
+  mkdir /out
+  # see also ".mailmap" for how email addresses and names are deduplicated
+  {
+    echo "# This file lists all individuals having contributed content to the repository."
+    echo "# For how it is generated, see hack/dockerfiles/authors.Dockerfile."
+    echo
+    git log --format='%aN <%aE>' | LC_ALL=C.UTF-8 sort -uf
+  } > /out/AUTHORS
+  cat /out/AUTHORS
+EOT
+
+FROM scratch AS update
+COPY --from=gen /out /
+
+FROM gen AS validate
+RUN --mount=type=bind,target=.,rw <<EOT
+  set -e
+  git add -A
+  cp -rf /out/* .
+  if [ -n "$(git status --porcelain -- AUTHORS)" ]; then
+    echo >&2 'ERROR: Authors result differs. Please update with "make authors"'
+    git status --porcelain -- AUTHORS
+    exit 1
+  fi
+EOT