Warthog

Cross-project release orchestration for Gradle, at scale. Make changes in one project, cut a release, publish the build artifacts, then adopt new packages in dependent projects — using just one command.

What is Warthog?

A typical scenario: a bunch of projects with complex interdependencies. A team wants to make a release to a library that needs to filter through to other projects which might depend on it. What's involved? A heap of testing for starters. Then publishing build artifacts to a central repository, tagging releases in Git and rolling over to the next snapshot version. What about the teams that depend on this library? They need to discover the latest version, update build files and run tests. And if you have a deep dependency graph, then the same needs to be repeated.

Warthog is a simple command-line tool that assists with dependency propagation. It does two things: first — it helps you incorporate updated packages into your Gradle build; second — it lets you publish updates and tag releases in a standardised and repeatable manner.

How it works

Warthog relies on a simple config file named .hog.project in the root directory of your Gradle project. A real-world example of .hog.project is shown below.

commands:
  build: ./gradlew test cleanIntegrationTest integrationTest --info --stacktrace --no-daemon
  publish: ./gradlew -x test publishToSonatype closeAndReleaseSonatypeStagingRepository --no-daemon
modules:
- path: .
  dependencies:
  - name: fulcrum
    groupId: com.obsidiandynamics.fulcrum
    artifactId: fulcrum-func
  - name: yconf
    groupId: com.obsidiandynamics.yconf
    artifactId: yconf-core
  - name: zerolog
    groupId: com.obsidiandynamics.zerolog
    artifactId: zerolog-core
- path: ledger-meteor
  dependencies:
  - name: meteor
    groupId: com.obsidiandynamics.meteor
    artifactId: meteor-core
- path: ledger-kafka
  dependencies:
  - name: jackdaw
    groupId: com.obsidiandynamics.jackdaw
    artifactId: jackdaw-core
versionist:
  type: com.obsidiandynamics.warthog.versionist.GradleVersionist

The .hog.project file is divided into three sections: commands, modules and versionist (the last one being optional). The build command is invoked as part of the update workflow, after patching the build scripts and downloading new Maven packages — ensuring that the build still passes. The publish command is used as part of the release workflow — uploading the newly-built artifacts into a central repository (e.g., Sonatype).

The modules section lists the relevant Gradle modules that are in the scope of the update workflow. The path attribute specifies the location of the module, relative the project's root directory. For example, path: . implies the root module, while path: ledger-meteor points to the module located in the ledger-meteor subdirectory within the project. A module has a list of dependencies. Each dependency is essentially a Maven package that is subject to updates. The groupId and artifactId are self-explanatory, and relate to the package itself. The name attribute is a special name that is given to a package (or a related group of packages) and must appear in your build.gradle file(s), in the form nameVersion = "x.y.z".

The example below illustrates how the packages fulcrum, yconf and zerolog are referenced and versioned in a Gradle build, following a convention that Warthog understands.

ext {
  fulcrumVersion = "0.16.0"   // version of the 'fulcrum' library
  yconfVersion = "0.6.0"      // version of the 'yconf' library
  zerologVersion = "0.17.0"   // version of the 'zerolog' library
}

dependencies {
  api "com.obsidiandynamics.fulcrum:fulcrum-concat:${fulcrumVersion}"        // a 'fulcrum' package
  api "com.obsidiandynamics.fulcrum:fulcrum-flow:${fulcrumVersion}"           // a 'fulcrum' package
  api "com.obsidiandynamics.fulcrum:fulcrum-func:${fulcrumVersion}"          // a 'fulcrum' package
  api "com.obsidiandynamics.yconf:yconf-core:${yconfVersion}"                // a 'yconf' package
  api "com.obsidiandynamics.zerolog:zerolog-core:${zerologVersion}"          // a 'zerolog' package
  api "org.apache.commons:commons-lang3:3.7"                                 // another package that Warthog doesn't care about
}

The real magic happens when Warthog parses the build file, looking for that coveted nameVersion = ... string. As soon as it finds a nameVersion assignment matching one of the dependencies listed in .hog.project, it queries the repository for the latest version and then patches the source build.gradle file, replacing the original version with what's in the repository. For example, if the latest version of fulcrum is now 0.17.0, then the string fulcrumVersion = "0.16.0" is patched to fulcrumVersion = "0.17.0".

In the above example, the fulcrum library actually includes three artifacts: fulcrum-concat, fulcrum-flow and fulcrum-func; however, we got lazy and only declared one in .hog.project. That's fine — Warthog just needs one artifact to establish the latest version; it doesn't matter which one or whether it is even in the build file — as long as all artifacts in the group share the same version. Where this isn't the case (for example, Apache HttpComponents, which uses non-uniform versioning within the same group), we'll have to make do with a dedicated nameVersion string per artifact, as shown below.

ext {
  httpclientVersion = "4.5.5"
  httpasyncclientVersion = "4.1.3"
}

dependencies {
  api "org.apache.httpcomponents:httpclient:${httpclientVersion}"
  api "org.apache.httpcomponents:httpasyncclient:${httpasyncclientVersion}"
}

The versionist section is optional. It allows you to specify how to manage project versions when preparing a release. The default versionist is GradleVersionist, which reads a version string from the root build.gradle file and patches the build file with a new version during the release step. Warthog's Gradle versionist expects the project version to be in the form version = "x.y.z[-qualifier]".

Alternatively, use FileVersionist if you prefer to keep your project in a separate file outside of build.gradle. The example below instructs Warthog's file versionist to source the version from src/main/resources/app.version (the path must be relative to the project directory). The version must be stored in a single-line file containing only text in the form x.y.z[-qualifier].

versionist:
  type: com.obsidiandynamics.warthog.versionist.FileVersionist
  versionFile: src/main/resources/app.version

Getting Started

Requirements

Warthog works on *NIX and macOS and requires a local installation of Java 10 JDK. We also need Git. Windows-based environments are not supported.

JDK 10 is only a requirement to build and run Warthog; the actual projects may be built with an appropriate version of the JDK.

Installation

Paste the following into a terminal.

git clone https://github.com/obsidiandynamics/warthog
cd warthog
./gradlew build
sudo run/install

This checks out a fresh copy of Warthog, runs the build (including tests), installs a symbolic link from /usr/local/bin/hog to run/hog. From there on, if you need to update Warthog, simply do a git pull, followed by ./gradlew build.

Running Warthog

Update workflow

In the root directory of the project that needs updating, run the following:

hog update

That's it. Assuming that a valid .hog.project exists, Warthog will —

Verify that the working copy has no uncommitted or untracked changes;
Verify that the local repository is in sync with the remote;
Pull any changes from the remote;
Scan all declared modules, looking for packages that have fallen behind their latest versions;
Patch the build files, pointing to the latest dependency versions; and
Run the build (using the build command specified in .hog.project), verifying that it's still sane.

Steps 1–3 are recommended to avoid conflicts when the changes are committed back in. You can skip them by passing the --skip-prep flag to hog.

Step 6 can be skipped with --skip-build.

Release workflow

To cut a release of our project and publish the relevant artifacts, run the following:

hog release

Warthog will —

Pull any changes into the working copy;
Commit the patched build files from the previous step (and any other tracked pending changes that happen to be in your working copy, so beware);
Change the project version from a snapshot to a release, by patching the root build.gradle file, i.e., x.y.z-SNAPSHOT becomes x.y.z (alternatively FileVersionist can be used to patch a dedicated version file);
Commit the patched build.gradle (or a custom version file) with the message [Warthog] Release x.y.z (replacing x.y.z with the release version);
Tag the last commit (tag is named x.y.z and the message is Release x.y.z);
Push the tag to remote;
Publish the build artifacts (using the publish command specified in .hog.project);
Roll the project minor version in the root build.gradle and mark it as a snapshot; i.e., x.y.z becomes x.(y+1).z-SNAPSHOT (alternatively FileVersionist can be used to patch a dedicated version file);
Commit build.gradle (or a custom version file) with the new snapshot version; and
Push build.gradle to remote.

The commit message in step 2 can be overridden with the --message argument. The default is [Warthog] Updated dependencies.

Steps 5–6 can be skipped with --skip-tag.

Step 7 can be skipped with --skip-publish.

Note: Warthog expects the project version to be in the form x.y.z[-qualifier]. The version must conform to Maven conventions and may have optional qualifiers. The second segment from the left (the minor version) will be incremented in the release workflow as part of staging the next snapshot, and therefore must be numeric.

Custom Repositories

By default, Warthog queries the Maven Central repository (https://repo1.maven.org/maven2) for package versions.

Warthog can be instructed to use any Maven-compliant repository (for example, your organisation's internal repo) by overriding the repoUrl attribute in the dependency configuration, as shown in the example below.

commands:
modules:
- path: .
  dependencies:
  - name: private-dependency
    groupId: com.private
    artifactId: private-thing
    repoUrl: https://repo.company.com/packages

Gotchas

Warthog workflows take care in ensuring that they operate on clean working copies and synced local repos. The likelihood of collisions is low, but not zero. Warthog will terminate if any of the orchestrated operations fail, leaving you to resolve conflicts manually.
If running update and release with a time gap in-between, it's recommended that you commit any work that you may have done separately, so it doesn't get bundled into Warthog's commits.
Tagging does not automatically include release notes, as this is outside the scope of plain Git. (GitHub, GitLab, BitBucket, et al. have their own concept of releases.) You'll need to manually write up a release and link it to a prior tag. (Future Warthog could offer deeper integration into hosted repositories.)

Limitations

Only Gradle is supported, with and without the wrapper. Other build tools, such as Maven, SBT, Ant/Ivy, etc. are not supported.
For the update workflow, the dependency versions must appear in build.gradle files in the strict nameVersion = "x.y.z[-qualifier]" form described earlier.
When using GradleVersionist, the version must be in the root build.gradle file and follow the strict version = "x.y.z[-qualifier]" form described earlier.
When using FileVersionist, the version file must be stored in a dedicated file (containing nothing but the version).
Custom auth for private repos isn't supported at this stage. The assumption is that the repo is reachable solely via a private/trusted network and that the machine running hog has implicit access.

FAQ

Is Warthog orchestrated using Warthog?

An obligatory question. To dispel hypocrisy — yes, it is.

Where did the name Warthog come from?

The answer could have been along the lines of "it was the only name that wasn't taken" or "because warthogs are particularly good at such and such" or "it's an exotic acronym" or even "the word 'hog' is particularly easy to type". The truth is that any answer is as good (or bad) as the next; there is no rationale behind the naming.

How is this different from Gradle Versions Plugin?

There is lots of overlap for identifying prospective package updates, and the two can be used together effectively. Warthog is still in its infancy, and is mostly concerned with orchestrating updates and standardising releases. (Automation, in one word.)

Gradle Versions Plugin (GVP) integrates tightly with Gradle and provides a comprehensive report on both plugin and dependency versions, requiring nothing more than your existing Gradle setup. But GVP cannot orchestrate version updates, verify builds, perform tagged releases or publish artifacts. And although GVP is only a reporting tool, it doesn't make it any less useful — just a bit different to Warthog.