github: add rake task to backport PR

.github/workflows/backport.yml

@@ -0,0 +1,37 @@
+name: Backport
+
+on:
+  schedule:
+    # Sun 10:00 (JST)
+    - cron: '0 1 * * 0'
+  workflow_dispatch:
+
+permissions: read-all
+
+concurrency:
+  group: ${{ github.head_ref || github.sha }}-${{ github.workflow }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    continue-on-error: false
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby-version: ['3.4']
+        task: ['backport:v1_16', 'backport:v1_19']
+
+    name: Backport PR on ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@8aeb6ff8030dd539317f8e1769a044873b56ea71 # v1.268.0
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+      - name: Install dependencies
+        run: bundle install
+      - name: Run Benchmark
+        shell: bash
+        run: |
+          bundle exec rake ${{ matrix.task }}

Rakefile

@@ -6,6 +6,7 @@ require 'rake/testtask'
 require 'rake/clean'
 
 require_relative 'tasks/benchmark'
+require_relative 'tasks/backport'
 
 task test: [:base_test]
 

tasks/backport.rb

@@ -0,0 +1,32 @@
+require_relative 'backport/backporter'
+
+namespace :backport do
+
+  desc "Backport PR to v1.16 branch"
+  task :v1_16 do
+    backporter = PullRequestBackporter.new
+    commands = ['--branch', 'v1.16', '--log-level', 'debug']
+    if ENV['DRY_RUN']
+      commands << '--dry-run'
+    end
+    if ENV['GITHUB_REPOSITORY']
+      commands << '--upstream'
+      commands << ENV['GITHUB_REPOSITORY']
+    end
+    backporter.run(commands)
+  end
+
+  desc "Backport PR to v1.19 branch"
+  task :v1_19 do
+    commands = ['--branch', 'v1.19', '--log-level', 'debug']
+    if ENV['DRY_RUN']
+      commands << '--dry-run'
+    end
+    if ENV['GITHUB_REPOSITORY']
+      commands << '--upstream'
+      commands << ENV['GITHUB_REPOSITORY']
+    end
+    backporter = PullRequestBackporter.new
+    backporter.run(commands)
+  end
+end

tasks/backport/backporter.rb

@@ -0,0 +1,143 @@
+require 'open-uri'
+require 'json'
+require 'optparse'
+require 'logger'
+
+class PullRequestBackporter
+
+  def initialize
+    @logger = Logger.new(STDOUT)
+    @options = {
+      upstream: "kenhys/fluentd",
+      branch: "v1.16",
+      dry_run: false,
+      log_level: Logger::Severity::INFO
+    }
+  end
+
+  def parse_command_line(argv)
+    opt = OptionParser.new
+    opt.on('--upstream REPOSITORY',
+           'Specify upstream repository (e.g. fluent/fluentd)') {|v| @options[:upstream] = v }
+    opt.on('--branch BRANCH') {|v| @options[:branch] = v }
+    opt.on('--dry-run') {|v| @options[:dry_run] = true }
+    opt.on('--log-level LOG_LEVEL (e.g. debug,info)') {|v|
+      @options[:log_level] = case v
+                             when "error"
+                               Logger::Severity::ERROR
+                             when "warn"
+                               Logger::Severity::WARN
+                             when "debug"
+                               Logger::Severity::DEBUG
+                             when "info"
+                               Logger::Severity::INFO
+                             else
+                               puts "unknown log level: <#{v}>"
+                               exit 1
+                             end
+    }
+    opt.parse!(argv)
+  end
+
+  def collect_backports
+    backports = []
+    5.times.each do |page|
+      @logger.debug "Collecting backport information"
+      URI.open("https://api.github.com/repos/fluent/fluentd/pulls?state=closed&per_page=100&page=#{page+1}",
+               "Accept" => "application/vnd.github+json",
+               "Authorization" => "Bearer #{ENV['GITHUB_TOKEN']}",
+               "X-GitHub-Api-Version" => "2022-11-28") do |request|
+        JSON.parse(request.read).each do |pull_request|
+          unless pull_request["labels"].empty?
+            labels = pull_request["labels"].collect { |label| label["name"] }
+            unless labels.include?("backport to #{@options[:branch]}")
+              next
+            end
+            if labels.include?("backported")
+              @logger.info "[DONE] \##{pull_request['number']} #{pull_request['title']} LABELS: #{pull_request['labels'].collect { |label| label['name'] }}"
+              next
+            end
+            @logger.info "* \##{pull_request['number']} #{pull_request['title']} LABELS: #{pull_request['labels'].collect { |label| label['name'] }}"
+            # merged into this commit
+            @logger.debug "MERGE_COMMIT_SHA: #{pull_request['merge_commit_sha']}"
+            body = pull_request["body"].gsub(/\*\*Which issue\(s\) this PR fixes\*\*: \r\n/,
+                                             "**Which issue(s) this PR fixes**: \r\nBackport \##{pull_request['number']}\r\n")
+            backports << {
+              number: pull_request["number"],
+              merge_commit_sha: pull_request["merge_commit_sha"],
+              title: "Backport(#{@options[:branch]}): #{pull_request['title']} (\##{pull_request['number']})",
+              body: body
+            }
+          end
+        end
+      end
+    end
+    backports
+  end
+
+  def create_pull_requests
+    backports = collect_backports
+    if backports.size == 0
+      @logger.debug "No need to backport: #{backports.size} PR"
+      return
+    end
+
+    failed = []
+    backports.each do |backport|
+      @logger.info "Backport #{backport[:number]} #{backport[:title]}"
+      if @options[:dry_run]
+        @logger.info "DRY_RUN: PR was created: \##{backport[:number]} #{backport[:title]}"
+        next
+      end
+      begin
+        branch = "backport-#{backport[:number]}"
+        @logger.debug "git switch --create #{branch} --track origin/#{@options[:branch]}"
+        IO.popen(["git", "switch", "--create",  branch, "--track",  "origin/#{@options[:branch]}"]) do |io|
+          @logger.debug io.read
+        end
+        @logger.info `git branch`
+        @logger.info "cherry-pick for #{backport[:number]}"
+        @logger.debug "git cherry-pick --signoff #{backport[:merge_commit_sha]}"
+        IO.popen(["git", "cherry-pick", "--signoff", backport[:merge_commit_sha]]) do |io|
+          @logger.debug io.read
+        end
+        if $? != 0
+          @logger.warn "Give up cherry-pick for #{backport[:number]}"
+          @logger.debug `git cherry-pick --abort`
+          failed << backport
+          next
+        else
+          @logger.info "Push branch: #{branch}"
+          @logger.debug `git push origin #{branch}`
+        end
+
+        @logger.debug "Create pull request: #{branch}"
+        upstream_repo = "/repos/#{@options[:upstream]}/pulls"
+        owner = @options[:upstream].split('/').first
+        head = "#{owner}:#{branch}"
+        IO.popen(["gh", "api", "--method", "POST",
+                  "-H", "Accept: application/vnd.github+json",
+                  "-H", "X-GitHub-Api-Version: 2022-11-28",
+                  upstream_repo,
+                  "-f", "title=#{backport[:title]}",
+                  "-f", "body=#{backport[:body]}",
+                  "-f", "head=#{head}",
+                  "-f", "base=#{@options[:branch]}"]) do |io|
+          json = JSON.parse(io.read)
+          @logger.info "PR was created: #{json['url']}"
+        end
+      rescue => e
+        @logger.error "ERROR: #{backport[:number]} #{e.message}"
+      end
+    end
+    failed.each do |backport|
+      @logger.error "FAILED: #{backport[:number]} #{backport[:title]}"
+    end
+  end
+
+  def run(argv)
+    parse_command_line(argv)
+    @logger.info("Target upstream: #{@options[:upstream]} target branch: #{@options[:branch]}")
+    create_pull_requests
+  end
+end