Add changelog script (#39148)

Makefile

@@ -1486,7 +1486,12 @@ rustup-install-target-toolchain:
 # changelog generates PR changelog between the provided base tag and the tip of
 # the specified branch.
 #
+# usage: make changelog
+# usage: make changelog BASE_BRANCH=branch/v13 BASE_TAG=13.2.0
 # usage: BASE_BRANCH=branch/v13 BASE_TAG=13.2.0 make changelog
+#
+# BASE_BRANCH and BASE_TAG will be automatically determined if not specified.
+# See ./build.assets/changelog.sh
 .PHONY: changelog
 changelog:
-	@python3 ./build.assets/changelog.py BASE_BRANCH=$(BASE_BRANCH) BASE_TAG=$(BASE_TAG)
+	@BASE_BRANCH=$(BASE_BRANCH) BASE_TAG=$(BASE_TAG) ./build.assets/changelog.sh

build.assets/changelog.sh

@@ -0,0 +1,204 @@
+#!/bin/bash
+#
+# This script generates a changelog for a release.
+#
+# It can optionally take two input variables: BASE_BRANCH: The base release
+# branch to generate the changelog for. It will be of the form "branch/v*".
+# BASE_TAG: The tag/version to generate the changelog from. It will be of the
+# form "vXX.Y.Z", e.g. "v15.1.1"
+#
+# If neither are provided, the values will be automatically determined if
+# possible:
+# * The current branch will be used as the base branch if it matches the
+#   pattern branch/v*
+# * If the current branch is forked from a base branch, the base branch will be
+#   used. e.g. if you create release/15.1.1 from branch/v15, the branch/v15
+#   will be the base branch.
+# * The base tag will be determined by running "make print-version" from the
+#   root of the repo.
+#
+# Enterprise PR changelogs will be listed after the OSS changelogs. You need to
+# determine if it is suitable to include them. If you do, remove the markdown
+# link from each changelog when adding the changelog to CHANGELOG.md. These
+# links wont work for the general public. Keep the links when adding the
+# changelog to the release PR so that the enterprise PRs will link to the
+# release PR.
+#
+# A changelog line may be marked with "NOCL:". This means there was no
+# "Changelog:" line on the PR, and the PR title was used instead. You will
+# likely need to reword these.
+#
+# If you reword changelogs, it is best to go to the source PR and change it
+# there and then regenerate the changelog.
+#
+# Caveats:
+# * If you update the "e" ref in your release PR, and you also run `make
+#   changelog` from the release PR branch, if you have already updated the
+#   version in the makefile, you will need to run `make changelog
+#   BASE_TAG=X.Y.Z` as this script will determine the base tag to be the
+#   current release version not the last released version.
+#
+# One preferred way of using this script is to run `make changelog` from the
+# base branch and save it: `make changelog > /tmp/changelog`. If any PRs are
+# merged to the base branch after you have created your release PR but before
+# you have merged it, you can see any new entries with:
+#
+#     git checkout branch/vNN
+#     diff -u /tmp/changelog $(make changelog)
+#
+# If there are changes, you can update your changelog and rebase your branch:
+#
+#     git pull # on branch/vNN
+#     make changelog > /tmp/changelog
+#     git checkout release/XX.Y.Z
+#     git rebase branch/vNN
+#     <include /tmp/changelog in CHANGELOG.md>
+#     git add CHANGELOG.md && git commit --amend --no-edit && git push -f
+#
+# Ensure you update the PR body with the new changelog, doable on the command
+# line with `gh`:
+#
+#     gh pr edit --body-file /tmp/changelog
+#
+
+# Set by check_prereq - either jq or gojq
+JQ=
+
+main() {
+	set -eu
+
+	check_prereq || exit 1
+
+	local branch last_version
+	branch=$(get_branch) || exit 1
+	last_version=$(get_last_version) || exit 1
+
+	since=$(git show -s --date=format:'%Y-%m-%dT%H:%M:%S%z' --format=%cd "${last_version}") || {
+		echo 'Cant get timestamp of last release' >&2
+		return 1
+	}
+	since_e=$(git -C e show -s --date=format:'%Y-%m-%dT%H:%M:%S%z' --format=%cd "${last_version}") || {
+		echo 'Cant get enterprise timestamp of last release' >&2
+		return 1
+	}
+	e_time=$(git log -n 1 --date=format:'%Y-%m-%dT%H:%M:%S%z' --format=%cd e) || {
+		echo 'Cant get last modified time of "e" ref' >&2
+		return 1
+	}
+
+	list_prs "${branch}" "${since}"
+	printf '\nEnterprise:\n'
+	(cd e && list_prs "${branch}" "${since_e}" "${e_time}")
+
+	return 0
+}
+
+check_prereq() {
+	if command -v jq >/dev/null 2>&1; then
+		JQ=jq
+		return 0
+	fi
+	if command -v gojq >/dev/null 2>&1; then
+		JQ=gojq
+		return 0
+	fi
+
+	echo 'jq or gojq not installed. Install gojq easily with:' >&2
+	echo 'go install github.com/itchyny/gojq/cmd/gojq@latest' >&2
+	return 1
+}
+
+get_branch() {
+	# If BASE_BRANCH is set, just use that. Otherwise try to figure it out.
+	if [[ -n "${BASE_BRANCH-}" ]]; then
+		echo "${BASE_BRANCH}"
+		return 0
+	fi
+
+	local ref branch
+	ref=$(git symbolic-ref HEAD 2>/dev/null) || {
+		echo 'Not on a branch' >&2
+		return 1
+	}
+	branch="${ref#refs/heads/}"
+	if [[ "${ref}" == "${branch}" ]]; then
+		echo "Not on a branch: ${ref}" >&2
+		return 1
+	fi
+
+	if [[ "${branch}" != branch/v* ]]; then
+		# If we're already on the branch cut for the release, try to
+		# determine the root branch name
+		local fbranch
+		fbranch=$(
+			git branch \
+				--list 'branch/v*' \
+				--contains "$(git merge-base --fork-point HEAD)" \
+				--format '%(refname:short)'
+		)
+		branch="${fbranch:-${branch}}" # Don't overwrite $branch with empty
+	fi
+	if ! [[ "${branch}" == branch/v* ]]; then
+		echo "Not on a release branch: ${branch}" >&2
+		return 1
+	fi
+
+	echo "${branch}"
+	return 0
+}
+
+get_last_version() {
+	# If BASE_TAG is set, just use that, otherwise figure out the last version
+	if [[ -n "${BASE_TAG-}" ]]; then
+		echo "${BASE_TAG}"
+		return 0
+	fi
+
+	cd "$(git rev-parse --show-toplevel 2>/dev/null)" || {
+		echo 'ugh. cant cd to repo root' >&2
+		return 1
+	}
+	local last_version
+	last_version=$(make -s print-version) || {
+		echo 'Cant get last released version' >&2
+		return 1
+	}
+
+	echo "v${last_version}"
+	return 0
+}
+
+list_prs() {
+	local branch="$1" from="$2" to="${3-}"
+	local merged_query
+	if [[ -z "${to}" ]]; then
+		merged_query="merged:>${from}"
+	else
+		merged_query="merged:${from}..${to}"
+	fi
+
+	local gh_query="base:${branch} ${merged_query} -label:no-changelog"
+
+	# shellcheck disable=SC2016 # We're not trying to expand in single quotes
+	jq_expr='
+	  def extract_cl: gsub("\r"; "") | split("\n") | [.[] | scan("^[Cc]hangelog: +(.*)$") | .[]];
+	  def promote_title: {number, url, changelog: (if .changelog == [] then ["NOCL: " + .title] else .changelog end)};
+	  def flatten_changes: . as $pr | .changelog[] | $pr + {changelog: .};
+	  def clean: sub("\\s*$"; "") | if . | endswith(".") then . else . + "." end;
+	  def as_entry: "* \(.changelog | clean) [#\(.number)](\(.url))";
+	  map({number, url, title, changelog: .body | extract_cl}) |
+	  map(promote_title) |
+	  map(flatten_changes) |
+	  map(as_entry) |
+	  join("\n")
+	'
+
+	gh pr list \
+		--search "${gh_query}" \
+		--limit 200 \
+		--json number,url,title,body |
+		"${JQ}" -r "${jq_expr}"
+}
+
+# Only run main if executed as a script and not sourced.
+if [[ "${BASH_SOURCE[0]}" == "$0" ]]; then main "$@"; fi