Add workflow for creating release branches

This change adds a GitHub Actions workflow for creating release branches
with jobs to 1) create the branch and 2) open a pull request with the
generated THIRD_PARTY_LICENSES file and updated getting started guide
version.

Signed-off-by: Austin Vazquez <[email protected]>

.github/workflows/create-release-branch.yml

@@ -0,0 +1,130 @@
+name: Create release branch
+
+on:
+  workflow_dispatch:
+    inputs:
+      major_minor_version:
+        description: 'Major.Minor release version'
+        required: true
+      base_commit:
+        description: 'Base commit SHA'
+        required: true
+  pull_request:
+    # Workflow should only ever be run from main, so exclude
+    # running on pull requests to release branch resources.
+    branches: ['main']
+    paths:
+      # Run workflow on changes to the workflow definition and its
+      # dependencies to spot check the workflow functionality.
+      - '.github/workflows/create-release-branch.yml'
+      - 'scripts/create-release-branch.sh'
+      - 'scripts/build-third-party-licenses.sh'
+      - 'scripts/update-getting-started-guide-.sh'
+
+jobs:
+  test-create-branch:
+    if: github.event_name == 'pull_request'
+    runs-on: ubuntu-20.04
+
+    env:
+      VERSION: ''
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Mock workflow inputs on pull request
+        run: |
+          echo "VERSION=0.${{ github.event.pull_request.number }}" >> $GITHUB_ENV
+
+      - name: Test create release branch
+        run: bash scripts/create-release-branch.sh --assert --base ${{ github.sha }} --dry-run ${{ env.VERSION }}
+
+      - uses: actions/setup-go@v5
+
+      - name: Install go-licenses
+        run: go install github.com/google/[email protected]
+
+      - name: Generate third party licenses file
+        run: bash scripts/build-third-party-licenses.sh
+
+      - name: Test update getting started version in release branch
+        run: bash scripts/update-getting-started-guide-version.sh --assert ${{ env.VERSION }}.0
+
+  create-branch:
+    if: github.event_name == 'workflow_dispatch'
+    runs-on: ubuntu-20.04
+
+    permissions:
+      # Write permissions needed to create release branch.
+      # Risk for pwn requests is mitigated by seperating jobs such that
+      # workflows running with write permissions only use code from main.
+      contents: write
+
+    env:
+      VERSION: ''
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: main
+          sparse-checkout: |
+            scripts/create-release-branch.sh
+
+      - name: Set environment variable version to output to dependent jobs
+        run: |
+          echo "VERSION=${{ github.event.inputs.major_minor_version }}" >> $GITHUB_ENV
+
+      - name: Create release branch
+        run: bash scripts/create-release-branch.sh --base ${{ github.event.inputs.base_commit }} ${{ github.event.inputs.major_minor_version }}
+
+    outputs:
+      version: ${{ env.VERSION }}
+
+  initial-pr:
+    needs: create-branch
+    if: github.event_name == 'workflow_dispatch' && needs.create-branch.result == 'success'
+    runs-on: ubuntu-20.04
+
+    permissions:
+      # Write permissions needed to create pull request.
+      # Risk for pwn requests is mitigated by seperating jobs such that
+      # workflows running with write permissions only use code from the
+      # branch which was cut from main.
+      contents: write
+      pull-requests: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: release/${{ needs.create-branch.outputs.version }}
+
+      - uses: actions/setup-go@v5
+
+      - name: Install go-licenses
+        run: go install github.com/google/[email protected]
+
+      - name: Generate third party licenses file
+        run: bash scripts/build-third-party-licenses.sh
+
+      - name: Update getting started version in release branch
+        run: bash scripts/update-getting-started-guide-version.sh --verbose "${{ needs.create-branch.outputs.version }}.0"
+
+      - name: Create PR
+        uses: peter-evans/create-pull-request@v6
+        with:
+          title: 'Prepare release ${{ needs.create-branch.outputs.version }}'
+          commit-message: |
+            Prepare release ${{ needs.create-branch.outputs.version }}
+
+            This change adds the THIRD_PARTY_LICENSES file and updates the getting started guide for release/${{ needs.create-branch.outputs.version }}.
+          body: |
+            This change adds the THIRD_PARTY_LICENSES file and updates the getting started guide for release/${{ needs.create-branch.outputs.version }}.
+
+            Auto-generated by [create-pull-request](https://github.com/peter-evans/create-pull-request)
+          labels: easy-to-review, automated-pr
+          token: ${{ secrets.GITHUB_TOKEN }}
+          author: "GitHub <[email protected]>"
+          signoff: true
+          branch: 'create-pull-request/prepare-release-${{ needs.create-branch.outputs.version }}'
+          base: 'release/${{ needs.create-branch.outputs.version }}'
+          delete-branch: true

.github/workflows/update-getting-started-guide.yml

@@ -4,7 +4,7 @@ on:
   release:
     types: ['released']
   pull_request:
-    branches: ['main', 'release/**']
+    branches: ['main']
     paths:
       # Run workflow on changes to the workflow definition itself to spot check
       # the core version update functionality.
@@ -45,8 +45,8 @@ jobs:
 
     permissions:
       # Write permissions needed to create pull request.
-      # Risk is mitigated by seperating jobs such that workflows
-      # running with write permissions only use code from main.
+      # Risk for pwn requests is mitigated by seperating jobs such that
+      # workflows running with write permissions only use code from main.
       contents: write
       pull-requests: write
 

scripts/create-release-branch.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+
+#   Copyright The Soci Snapshotter Authors.
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+# A script to create a release branch on origin from the given commit.
+#
+# Usage: bash create-release-branch.sh [-a|--assert] [-b|--base] [-d|--dry-run] <MAJOR_MINOR_VERSION>
+
+set -eux -o pipefail
+
+ASSERT=false
+BASE_COMMIT=""
+DRYRUN=false
+
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --assert|-a)
+      ASSERT=true
+      shift # past argument
+      ;;
+    --base|-b)
+      shift # past argument
+      BASE_COMMIT=$1
+      shift # past value
+      ;;
+    --dry-run|-d)
+      DRYRUN=true
+      shift # past argument
+      ;;
+    --*|-*)
+      echo "Unknown option $1"
+      exit 1
+      ;;
+    *)
+      VERSION=$1
+      shift # past argument
+      ;;
+  esac
+done
+
+sanitize_input() {
+  # Strip 'v' prefix from input if present.
+  VERSION=${VERSION/v/}
+  [[ $VERSION =~ ^[0-9]+\.[0-9]+$ ]] || (echo "Error: version does not match expected <major>.<minor> format" && exit 1)
+
+  if [ -n "$BASE_COMMIT" ]; then
+    [[ $BASE_COMMIT =~ ^[0-9a-fA-F]{7,40}$ ]] || (echo "Error: base commit does not match expected short|full format" && exit 1)
+    FOUND=$(git log --pretty=format:"%H" | grep "$BASE_COMMIT")
+    [ -n "$FOUND" ] || (echo "Error: base commit not found in history" && exit 1)
+  fi
+}
+
+assert_create_branch() {
+  local current_branch
+  current_branch=$(git rev-parse --abbrev-ref HEAD)
+  [ "$current_branch" = "release/${VERSION}" ] || (echo "Error: incorrect branch, expected: release/${VERSION}, actual: $current_branch" && exit 1)
+
+  local base_commit
+  base_commit=$(git show -s --format="%H")
+  [ "$base_commit" = "$BASE_COMMIT" ] || (echo "Error: incorrect base commit, expected: $BASE_COMMIT, actual: $base_commit" && exit 1)
+}
+
+sanitize_input
+
+git checkout -b "release/${VERSION}" "${BASE_COMMIT}"
+
+[ $ASSERT = true ] && assert_create_branch
+
+PUSH_CMD="git push origin release/${VERSION}"
+if [ $DRYRUN = true ]; then
+  # Dry-run mode is not able to use git push --dry-run as it still requires
+  # write permissions to the remote repository. The intent is to run dry-run mode
+  # in pull request workflows with a reduced permission set to mitigate risk for pwn requests.
+  # Alternatively assert the push command is correct.
+  [[ $PUSH_CMD == "git push origin release/${VERSION}" ]] || (echo "Error: expected: 'git push origin release/${VERSION}', actual: '$PUSH_CMD'" && exit 1)
+else
+  $PUSH_CMD
+fi

scripts/update-getting-started-guide-version.sh

@@ -21,8 +21,6 @@
 
 set -eux -o pipefail
 
-tag=$1
-
 ASSERT=false
 VERBOSE=false
 
@@ -41,14 +39,19 @@ while [[ $# -gt 0 ]]; do
       exit 1
       ;;
     *)
-      tag=$1
+      VERSION=$1
       shift # past argument
       ;;
   esac
 done
 
-# Strip 'v' prefix from tag if not already stripped.
-VERSION=${tag/v/} 
+sanitize_input() {
+  # Strip 'v' prefix from input if present.
+  VERSION=${VERSION/v/}
+  [[ $VERSION =~ ^([0-9]+\.){2}[0-9]+(-.*){0,1}$ ]] || (echo "Error: version does not match expect <major>.<minor>.<patch> version format" && exit 1)
+}
+
+sanitize_input
 
 assert_diff() {
   local diff_output