chore: add generation workflow (#2825)

In this PR:
- Add workflow and shell scripts used in library generation.

.github/scripts/hermetic_library_generation.sh

@@ -0,0 +1,119 @@
+#!/bin/bash
+set -e
+# This script should be run at the root of the repository.
+# This script is used to, when a pull request changes the generation
+# configuration (generation_config.yaml by default):
+# 1. Find whether the last commit in this pull request contains changes to
+# the generation configuration and exit early if it doesn't have such a change
+# since the generation result would be the same.
+# 2. Compare generation configurations in the current branch (with which the
+# pull request associated) and target branch (into which the pull request is
+# merged);
+# 3. Generate changed libraries using library_generation image;
+# 4. Commit the changes to the pull request, if any.
+# 5. Edit the PR body with generated pull request description, if applicable.
+
+# The following commands need to be installed before running the script:
+# 1. git
+# 2. gh
+# 3. docker
+
+# The parameters of this script is:
+# 1. target_branch, the branch into which the pull request is merged.
+# 2. current_branch, the branch with which the pull request is associated.
+# 3. image_tag, the tag of gcr.io/cloud-devrel-public-resources/java-library-generation.
+# 3. [optional] generation_config, the path to the generation configuration,
+# the default value is generation_config.yaml in the repository root.
+while [[ $# -gt 0 ]]; do
+key="$1"
+case "${key}" in
+  --target_branch)
+    target_branch="$2"
+    shift
+    ;;
+  --current_branch)
+    current_branch="$2"
+    shift
+    ;;
+  --image_tag)
+    image_tag="$2"
+    shift
+    ;;
+  --generation_config)
+    generation_config="$2"
+    shift
+    ;;
+  *)
+    echo "Invalid option: [$1]"
+    exit 1
+    ;;
+esac
+shift
+done
+
+if [ -z "${target_branch}" ]; then
+  echo "missing required argument --target_branch"
+  exit 1
+fi
+
+if [ -z "${current_branch}" ]; then
+  echo "missing required argument --current_branch"
+  exit 1
+fi
+
+if [ -z "${image_tag}" ]; then
+  echo "missing required argument --image_tag"
+  exit 1
+fi
+
+if [ -z "${generation_config}" ]; then
+  generation_config=generation_config.yaml
+  echo "Use default generation config: ${generation_config}"
+fi
+
+workspace_name="/workspace"
+baseline_generation_config="baseline_generation_config.yaml"
+message="chore: generate libraries at $(date)"
+
+git checkout "${target_branch}"
+git checkout "${current_branch}"
+# if the last commit doesn't contain changes to generation configuration,
+# do not generate again as the result will be the same.
+change_of_last_commit="$(git diff-tree --no-commit-id --name-only HEAD~1..HEAD -r)"
+if [[ ! ("${change_of_last_commit}" == *"${generation_config}"*) ]]; then
+    echo "The last commit doesn't contain any changes to the generation_config.yaml, skipping the whole generation process." || true
+    exit 0
+fi
+# copy generation configuration from target branch to current branch.
+git show "${target_branch}":"${generation_config}" > "${baseline_generation_config}"
+config_diff=$(diff "${generation_config}" "${baseline_generation_config}" || true)
+
+# run hermetic code generation docker image.
+docker run \
+  --rm \
+  -u "$(id -u):$(id -g)" \
+  -v "$(pwd):${workspace_name}" \
+  -v "$HOME"/.m2:/home/.m2 \
+  gcr.io/cloud-devrel-public-resources/java-library-generation:"${image_tag}" \
+  --baseline-generation-config-path="${workspace_name}/${baseline_generation_config}" \
+  --current-generation-config-path="${workspace_name}/${generation_config}"
+
+# commit the change to the pull request.
+rm -rdf output googleapis "${baseline_generation_config}"
+git add --all -- ':!pr_description.txt'
+changed_files=$(git diff --cached --name-only)
+if [[ "${changed_files}" == "" ]]; then
+    echo "There is no generated code change with the generation config change ${config_diff}."
+    echo "Skip committing to the pull request."
+    exit 0
+fi
+
+echo "Configuration diff:"
+echo "${config_diff}"
+git commit -m "${message}"
+git push
+# set pr body if pr_description.txt is generated.
+if [[ -f "pr_description.txt" ]]; then
+  pr_num=$(gh pr list -s open -H "${current_branch}" -q . --json number | jq ".[] | .number")
+  gh pr edit "${pr_num}" --body "$(cat pr_description.txt)"
+fi

.github/scripts/update_googleapis_commit.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+set -e
+# This script should be run at the root of the repository.
+# This script is used to update googleapis commit to latest in generation
+# configuration at the time of running and create a pull request.
+
+# The following commands need to be installed before running the script:
+# 1. git
+# 2. gh
+
+# The parameters of this script is:
+# 1. base_branch, the base branch of the result pull request.
+# 2. repo, organization/repo-name, e.g., googleapis/google-cloud-java
+# 3. [optional] generation_config, the path to the generation configuration,
+# the default value is generation_config.yaml in the repository root.
+while [[ $# -gt 0 ]]; do
+key="$1"
+case "${key}" in
+  --base_branch)
+    base_branch="$2"
+    shift
+    ;;
+  --repo)
+    repo="$2"
+    shift
+    ;;
+  --generation_config)
+    generation_config="$2"
+    shift
+    ;;
+  *)
+    echo "Invalid option: [$1]"
+    exit 1
+    ;;
+esac
+shift
+done
+
+if [ -z "${base_branch}" ]; then
+  echo "missing required argument --base_branch"
+  exit 1
+fi
+
+if [ -z "${repo}" ]; then
+  echo "missing required argument --repo"
+  exit 1
+fi
+
+if [ -z "${generation_config}" ]; then
+  generation_config="generation_config.yaml"
+  echo "Use default generation config: ${generation_config}"
+fi
+
+current_branch="generate-libraries-${base_branch}"
+title="chore: update googleapis commit at $(date)"
+
+# try to find a open pull request associated with the branch
+pr_num=$(gh pr list -s open -H "${current_branch}" -q . --json number | jq ".[] | .number")
+# create a branch if there's no open pull request associated with the
+# branch; otherwise checkout the pull request.
+if [ -z "${pr_num}" ]; then
+  git checkout -b "${current_branch}"
+else
+  gh pr checkout "${pr_num}"
+fi
+
+mkdir tmp-googleapis
+# use partial clone because only commit history is needed.
+git clone --filter=blob:none https://github.com/googleapis/googleapis.git tmp-googleapis
+pushd tmp-googleapis
+git pull
+latest_commit=$(git rev-parse HEAD)
+popd
+rm -rf tmp-googleapis
+sed -i -e "s/^googleapis_commitish.*$/googleapis_commitish: ${latest_commit}/" "${generation_config}"
+
+git add "${generation_config}"
+changed_files=$(git diff --cached --name-only)
+if [[ "${changed_files}" == "" ]]; then
+    echo "The latest googleapis commit is not changed."
+    echo "Skip committing to the pull request."
+    exit 0
+fi
+git commit -m "${title}"
+if [ -z "${pr_num}" ]; then
+  git remote add remote_repo https://cloud-java-bot:"${GH_TOKEN}@github.com/${repo}.git"
+  git fetch -q --unshallow remote_repo
+  git push -f remote_repo "${current_branch}"
+  gh pr create --title "${title}" --head "${current_branch}" --body "${title}" --base "${base_branch}"
+else
+  git push
+fi

.github/workflows/hermetic_library_generation.yaml

@@ -0,0 +1,54 @@
+# Copyright 2024 Google LLC
+#
+# 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.
+# GitHub action job to test core java library features on
+# downstream client libraries before they are released.
+name: Hermetic library generation upon generation config change through pull requests
+on:
+  pull_request:
+
+jobs:
+  library_generation:
+    # skip pull requests come from a forked repository
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+        token: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}
+    - name: Build image
+      shell: bash
+      run: |
+        docker build \
+          -f .cloudbuild/library_generation/library_generation.Dockerfile \
+          -t gcr.io/cloud-devrel-public-resources/java-library-generation:latest \
+          .
+    - name: Install gapic-generator-java-pom-parent
+      shell: bash
+      run: |
+        mvn clean install -pl gapic-generator-java-pom-parent
+    - name: Generate changed libraries
+      shell: bash
+      run: |
+        set -x
+        [ -z "$(git config user.email)" ] && git config --global user.email "cloud-java-bot@google.com"
+        [ -z "$(git config user.name)" ] && git config --global user.name "cloud-java-bot"
+        bash .github/scripts/hermetic_library_generation.sh \
+          --target_branch "${base_ref}" \
+          --current_branch "${head_ref}" \
+          --image_tag latest
+      env:
+        base_ref: ${{ github.base_ref }}
+        head_ref: ${{ github.head_ref }}
+        GH_TOKEN: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}

.github/workflows/update_googleapis_commit.yaml

@@ -0,0 +1,42 @@
+# Copyright 2024 Google LLC
+#
+# 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.
+# GitHub action job to test core java library features on
+# downstream client libraries before they are released.
+name: Update googleapis commit
+on:
+  schedule:
+  - cron: '0 2 * * *'
+  workflow_dispatch:
+
+jobs:
+  update-googleapis-commit:
+    runs-on: ubuntu-22.04
+    env:
+      # the branch into which the pull request is merged
+      base_branch: main
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        token: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}
+    - name: Update googleapis commit to latest
+      shell: bash
+      run: |
+        set -x
+        [ -z "$(git config user.email)" ] && git config --global user.email "cloud-java-bot@google.com"
+        [ -z "$(git config user.name)" ] && git config --global user.name "cloud-java-bot"
+        bash .github/scripts/update_googleapis_commit.sh \
+          --base_branch "${base_branch}"\
+          --repo ${{ github.repository }}
+      env:
+        GH_TOKEN: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}