Simplified-Android-CI

The NYPL's Library Simplified CI scripts.

Image by Nowaja from Pixabay

Project	Status
Simplified-Android-Core
Simplified-Android-HTTP
Simplified-R2-Android
audiobook-android

What Is This?

The contents of this repository define the CI scripts used to continuously build the various Library Simplified Android modules.

Features

• Automatic deployment of application binaries to a git repository.
• Automatic deployment of snapshots and releases to Maven Central.
• Automatic deployment of Android applications to Firebase.
• Automatic deployment of Android releases to the Play Store.
• Build pull requests safely without access to secrets.
• Zero-configuration in the common case; add a git submodule and go!

Usage

First, add the CI scripts to your project as a Git submodule in a .ci directory:

$ git submodule add https://www.github.com/NYPL-Simplified/Simplified-Android-CI .ci

Per-project configuration data is expected to be placed into a .ci-local directory at the root of the project. Most projects will not need to define any configuration information. The scripts in .ci contain no user-serviceable parts.

The CI scripts only know how to build Gradle projects as, unfortunately, this is the only supported build system for use in Android projects. The CI scripts expect your Gradle project to define the following tasks:

Task	Description
clean	Deletes all build artifacts to guarantee a clean build
assemble	Builds all artifacts
test	Runs all tests
verifySemanticVersioning	Runs semantic versioning checks

The scripts expect all of these tasks to be defined, but it is possible to simply define empty tasks for ktlint and verifySemanticVersioning if the project in question does not use them.

The scripts expect your Gradle project to accept the following project properties:

Property	Value	Description
org.librarysimplified.no_signing	true/false	If true, no PGP signing of artifacts will occur
org.librarysimplified.directory.publish	Any path	If set, artifacts will be published to the named directory in Maven repository format
mavenCentralUsername	Any string	The username used to publish to Maven Central
mavenCentralPassword	Any string	The password used to publish to Maven Central

The entry point to the CI scripts is the ci-main.sh script. This script takes a single parameter specifying the type of build that will be performed. The CI scripts distinguish between different types of builds for reasons of security: Commits that are coming from a potentially untrustworthy third party might try to modify the CI scripts themselves in order to steal credentials and other build secrets when the build executes. Additionally, the build artifacts that are produced by commits coming from a potentially untrustworthy third party should not be automatically published to, for example, Maven Central.

The ci-main.sh script therefore defines the following build types:

Value	Description
normal	This is a normal build of code that has been reviewed. The build will be granted full access to secrets. The artifacts produced will be published to various locations.
pull-request	This is a build of a pull request. The build will proceed without access to secrets, and any build artifacts produced will not be published.
setup-only	This does all of the work of setting up for building, but does not actually build anything. The build will be granted full access to secrets.

Using GitHub Actions as an example, the intention is that projects will define a pair of workflows A and B. Workflow A is triggered when any commit is made to the develop or main branch of the repos, and calls $ ci-main.sh normal to perform a full build with secrets and publishing. Workflow B is triggered when a pull request is opened, and calls $ ci-main.sh pull-request to do a limited build without secrets or publishing. There is a facility to do extra handling of credentials and secrets if required.

Here are two example Workflow definitions that implement the above:

name: Android CI (Authenticated)

on:
  push:
    branches: [ develop, master ]
    tags: v[0-9]+.[0-9]+.[0-9]+

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout reposistory
        uses: actions/checkout@v2
      - name: Checkout submodules
        run: git submodule update --init --recursive
      - name: set up JDK 1.8
        uses: actions/setup-java@v1
        with:
          java-version: 1.8
      - name: Build
        env:
          MAVEN_CENTRAL_USERNAME:           ${{ secrets.MAVEN_CENTRAL_USERNAME }}
          MAVEN_CENTRAL_PASSWORD:           ${{ secrets.MAVEN_CENTRAL_PASSWORD }}
          MAVEN_CENTRAL_STAGING_PROFILE_ID: '3dbb9c4528708261'
          MAVEN_CENTRAL_SIGNING_KEY_ID:     'c8d9e0c27090998d'
          NYPL_GITHUB_ACCESS_TOKEN:         ${{ secrets.NYPL_GITHUB_ACCESS_TOKEN }}
        run: .ci/ci-main.sh normal

name: Android CI (Pull Requests)

on:
  pull_request:
    branches: [ develop ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout reposistory
        uses: actions/checkout@v2
      - name: Checkout submodules
        run: git submodule update --init --recursive
      - name: set up JDK 1.8
        uses: actions/setup-java@v1
        with:
          java-version: 1.8
      - name: Build PR
        run: .ci/ci-main.sh pull-request

Any produced aar and jar files produced during the build are automatically published to Maven Central. Specifically, iff the current git commit has a tag and the version number does not end with -SNAPSHOT, then a full staging workflow will be executed and the binaries will be published to the Maven Central repository. Iff the current git commit does not have a tag, and the version number ends with -SNAPSHOT, then the binaries will be published to the volatile Sonatype Snapshots repository. For untagged, non -SNAPSHOT versions, nothing is published to Maven Central.

Environment Variables

The build scripts require the following environment variables to be defined when executing a normal build. Executing a pull-request build does not require any particular environment.

Name	Description
MAVEN_CENTRAL_USERNAME	The username used to publish binaries to Maven Central
MAVEN_CENTRAL_PASSWORD	The password used to publish binaries to Maven Central
MAVEN_CENTRAL_STAGING_PROFILE_ID	The staging profile used to publish binaries to Maven Central
MAVEN_CENTRAL_SIGNING_KEY_ID	The ID of the PGP key used to sign binaries for Maven Central
NYPL_GITHUB_ACCESS_TOKEN	A GitHub access token used to access private NYPL repositories

These values should be stored in GitHub Actions secrets and passed in as shown in the example workflows above.

Maven Central Publishing

The CI scripts can be optionally configured to publish APK files to a Git repository. If the file .ci-local/deploy-maven-central.conf exists, the CI scripts will attempt to publish all produced artifacts to Maven Central.

APK Git Publishing

The CI scripts can be optionally configured to publish APK files to a Git repository. If the file .ci-local/deploy-git-binary-source.conf exists, the CI scripts will attempt to publish all produced APK files to a named branch in a remote Git repository. The configuration files in .ci-local follow the convention that only the first line of each file is significant, and the rest of the file is ignored. For example, to set up publishing to a remote Git repository, do the following:

$ echo 'https://github.com/NYPL-Simplified/Simplified-Android-SimplyE' > .ci-local/deploy-git-binary-source.conf
$ echo 'NYPL-Simplified/android-binaries' > .ci-local/deploy-git-binary-target.conf
$ echo 'app/version.properties' > .ci-local/deploy-git-binary-version-file.conf
$ echo 'SimplyE' > .ci-local/deploy-git-binary-branch.conf
$ git add .ci-local
$ git commit -m 'Configured CI'

The above set of configuration files will cause binaries to be published to the NYPL-Simplified/android-binaries repository on GitHub, on branch SimplyE. The file app/version.properties will be examined and is expected to be a Java properties file containing a versionCode key indicating the version code of the APK files being published. The commit made in the remote repository will contain a link back to the repository https://github.com/NYPL-Simplified/Simplified-Android-SimplyE, showing the exact commit that produced the binaries.

The possible configuration files are as follows:

File	Description
.ci-local/deploy-git-binary-source.conf	The first line of this file gives the URL of the source repository, used in commit messages
.ci-local/deploy-git-binary-target.conf	The first line of this file gives the GitHub-relative name of the target repository
.ci-local/deploy-git-binary-version-file.conf	The first line of this file gives the name of the file containing a versionCode property indicating the version of the build APK files
.ci-local/deploy-git-binary-branch.conf	The first line of this file gives the name of the branch to which binaries will be committed

Firebase Publishing

If the file .ci-local/deploy-firebase-apps.conf exists, each line of the file that does not begin with a '#' character is interpreted as the name of a Gradle submodule that contains an application to be deployed to Firebase. The submodule must contain the following files:

File	Description
firebase-aab.conf	The name of the AAB file to be deployed (such as org.librarysimplified.testing.app/build/outputs/aab/release/org.librarysimplified.testing.app-release-unsigned.aab)
firebase-apk.conf	The name of the APK file to be deployed (such as org.librarysimplified.testing.app/build/outputs/apk/release/org.librarysimplified.testing.app-release-unsigned.apk)
firebase-app-id.conf	The application ID to be deployed (such as 1:1076330259269:android:8cb4dc8d0e14bc32d3d42c)
firebase-groups.conf	The name(s) of the testing group(s) to notify (such as beta-testers)

Fastlane Publishing

If the file .ci-local/deploy-fastlane-apps.conf exists, each line of the file that does not begin with a '#' character is interpreted as the name of a Gradle submodule that contains an application to be deployed using Fastlane.

File	Description

Deploy Hook

If the file .ci-local/deploy.sh exists, it will be executed after all deployments have executed successfully in normal builds. This script allows for, for example, telling external services that new builds are available.

Credentials Hook

If the file .ci-local/credentials.sh exists, it will be executed after the build credentials have been configured in normal builds. This script allows for copying any extra required credentials into their expected places during the build. As an example:

$ cat .ci-local/credentials.sh
#!/bin/sh

fatal()
{
  echo "credentials.sh: fatal: $1" 1>&2
  exit 1
}

if [ -z "${SECRET_SITE_PASSWORD}" ]
then
  fatal "SECRET_SITE_PASSWORD is undefined"
fi

wget "https://user:${SECRET_SITE_PASSWORD}@example.com/secret.txt" ||
  fatal "could not fetch secret"
cp secret.txt app/src/main/assets/secret.txt ||
  fatal "could not copy secret"

If the file .ci-local/credentials-fake.sh exists, it will be executed before the code is built in pull-request builds. This script allows for setting up any fake credentials that might be required. For example, most projects that produce APK files will require some kind of keystore for APK signing, even if the APK is never deployed. The .ci-local/credentials-fake.sh script can be used to set up a temporary keystore that is simply discarded at the end of the build.