Prerequisites

To build Gerrit from source, you need:

  • A Linux or macOS system (Windows is not supported at this time)

  • A JDK for Java 8|9|10|11|…​

  • Python 2 or 3

  • Node.js

  • Bazel -launched with Bazelisk

  • Maven

  • zip, unzip

  • curl

  • gcc

Bazel

Bazelisk includes a Bazel version check and downloads the correct bazel version for the git project/repository. Bazelisk is the recommended bazel launcher for Gerrit. Once Bazelisk is installed locally, a bazel symlink can be created towards it. This is so that every bazel command seamlessly uses Bazelisk, which then runs the proper bazel binary version.

Java

Java 10 support

Java 10 is supported through vanilla java toolchain Bazel option. To build Gerrit with Java 10 and newer, specify vanilla java toolchain and provide the path to JDK home:

  $ bazel build \
    --define=ABSOLUTE_JAVABASE=<path-to-java-10> \
    --host_javabase=@bazel_tools//tools/jdk:absolute_javabase \
    --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla \
    --java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla \
    :release

To run the tests, --javabase option must be passed as well, because bazel test runs the test using the target javabase:

  $ bazel test \
    --define=ABSOLUTE_JAVABASE=<path-to-java-10> \
    --javabase=@bazel_tools//tools/jdk:absolute_javabase \
    --host_javabase=@bazel_tools//tools/jdk:absolute_javabase \
    --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla \
    --java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla \
    //...

To avoid passing all those options on every Bazel build invocation, they could be added to ~/.bazelrc resource file:

$ cat << EOF > ~/.bazelrc
> build --define=ABSOLUTE_JAVABASE=<path-to-java-10>
> build --javabase=@bazel_tools//tools/jdk:absolute_javabase
> build --host_javabase=@bazel_tools//tools/jdk:absolute_javabase
> build --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla
> build --java_toolchain=@bazel_tools//tools/jdk:toolchain_vanilla
> EOF

Now, invoking Bazel with just bazel build :release would include all those options.

Note that the follow option must be added to container.javaOptions in $gerrit_site/etc/gerrit.config to run Gerrit with Java 10|11|…​:

[container]
  javaOptions = --add-opens=jdk.management/com.sun.management.internal=ALL-UNNAMED

Java 9 support

Java 9 is supported through alternative java toolchain Bazel option. The Java 9 support is backwards compatible. Java 8 is still the default. To build Gerrit with Java 9, specify JDK 9 java toolchain:

  $ bazel build \
      --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_java9 \
      --java_toolchain=@bazel_tools//tools/jdk:toolchain_java9 \
      :release

Note that the follow option must be added to container.javaOptions in $gerrit_site/etc/gerrit.config to run Gerrit with Java 9:

[container]
  javaOptions = --add-opens=jdk.management/com.sun.management.internal=ALL-UNNAMED

Building on the Command Line

Gerrit Development WAR File

To build the Gerrit web application that includes the PolyGerrit UI:

  bazel build gerrit
Note
 PolyGerrit UI may require additional tools (such as npm). Please read the polygerrit-ui/README.md for more info.

The output executable WAR will be placed in:

  bazel-bin/gerrit.war

Gerrit Release WAR File

To build the Gerrit web application that includes the GWT UI, the PolyGerrit UI, core plugins and documentation:

  bazel build release

The output executable WAR will be placed in:

  bazel-bin/release.war

Headless Mode

To build Gerrit in headless mode, i.e. without the PolyGerrit and GWT Web UI:

  bazel build headless

The output executable WAR will be placed in:

  bazel-bin/headless.war

Extension and Plugin API JAR Files

To build the extension, plugin and GWT API JAR files:

  bazel build api

The output archive that contains Java binaries, Java sources and Java docs will be placed in:

  bazel-bin/api.zip

Install {extension,plugin,gwt}-api to the local maven repository:

  tools/maven/api.sh install

Install gerrit.war to the local maven repository:

  tools/maven/api.sh war_install

Plugins

  bazel build plugins:core

The output JAR files for individual plugins will be placed in:

  bazel-bin/plugins/<name>/<name>.jar

The JAR files will also be packaged in:

  bazel-bin/plugins/core.zip

To build a specific plugin:

  bazel build plugins/<name>

The output JAR file will be be placed in:

  bazel-bin/plugins/<name>/<name>.jar

Note that when building an individual plugin, the core.zip package is not regenerated.

To build with all Error Prone warnings activated, run:

  bazel build --java_toolchain //tools:error_prone_warnings_toolchain //...

Using an IDE.

IntelliJ

The Gerrit build works with Bazel’s IntelliJ plugin. Please follow the instructions on IntelliJ Setup.

Eclipse

Generating the Eclipse Project

Create the Eclipse project:

  tools/eclipse/project.py

and then follow the setup instructions.

Refreshing the Classpath

If an updated classpath is needed, the Eclipse project can be refreshed and missing dependency JARs can be downloaded by running project.py again. For IntelliJ, you need to click the Sync Project with BUILD Files button of IntelliJ plugin.

Documentation

To build only the documentation for testing or static hosting:

  bazel build Documentation:searchfree

The html files will be bundled into searchfree.zip in this location:

  bazel-bin/Documentation/searchfree.zip

To build the executable WAR with the documentation included:

  bazel build withdocs

The WAR file will be placed in:

  bazel-bin/withdocs.war

Running Unit Tests

  bazel test --build_tests_only //...

Debugging tests:

  bazel test --test_output=streamed --test_filter=com.gerrit.TestClass.testMethod testTarget

Debug test example:

  bazel test --test_output=streamed --test_filter=com.google.gerrit.acceptance.api.change.ChangeIT.getAmbiguous //javatests/com/google/gerrit/acceptance/api/change:api_change

To run a specific test group, e.g. the rest-account test group:

  bazel test //javatests/com/google/gerrit/acceptance/rest/account:rest_account

To run the tests against NoteDb backend with write to NoteDb, but not read from it:

  bazel test --test_env=GERRIT_NOTEDB=WRITE //...

Write and read from NoteDb:

  bazel test --test_env=GERRIT_NOTEDB=READ_WRITE //...

Primary storage NoteDb:

  bazel test --test_env=GERRIT_NOTEDB=PRIMARY //...

Primary storage NoteDb and ReviewDb disabled:

  bazel test --test_env=GERRIT_NOTEDB=ON //...

To run only tests that do not use SSH:

  bazel test --test_env=GERRIT_USE_SSH=NO //...

To exclude tests that have been marked as flaky:

  bazel test --test_tag_filters=-flaky //...

To exclude tests that require a Docker host:

  bazel test --test_tag_filters=-docker //...

To ignore cached test results:

  bazel test --cache_test_results=NO //...

To run one or more specific groups of tests:

  bazel test --test_tag_filters=api,git //...

The following values are currently supported for the group name:

  • annotation

  • api

  • docker

  • edit

  • elastic

  • git

  • git-upload-archive

  • notedb

  • pgm

  • rest

  • server

  • ssh

Elasticsearch

Successfully running the Elasticsearch tests requires Docker, and may require setting the local virtual memory on linux and macOS.

On macOS, if using Docker Desktop, the effective memory value can be set in the Preferences, under the Advanced tab. The default value usually does not suffice and is causing premature container exits. That default is currently 2 GB and should be set to at least 5 (GB).

If Docker is not available, the Elasticsearch tests will be skipped. Note that Bazel currently does not show the skipped tests.

Controlling logging level

Per default, logging level is set to INFO level for all tests. The DEBUG log level can be enabled for the tests.

In IDE, set -Dgerrit.logLevel=debug as a VM argument. With bazel, pass GERRIT_LOG_LEVEL=debug environment variable:

  bazel test --test_filter=com.google.gerrit.server.notedb.ChangeNotesTest \
  --test_env=GERRIT_LOG_LEVEL=debug \
  javatests/com/google/gerrit/server:server_tests

The log results can be found in: bazel-testlogs/javatests/com/google/gerrit/server/server_tests/test.log.

Dependencies

Dependency JARs are normally downloaded as needed, but you can download everything upfront. This is useful to enable subsequent builds to run without network access:

  bazel fetch //...

When downloading from behind a proxy (which is common in some corporate environments), it might be necessary to explicitly specify the proxy that is then used by curl:

  export http_proxy=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>

Redirection to local mirrors of Maven Central and the Gerrit storage bucket is supported by defining specific properties in local.properties, a file that is not tracked by Git:

  echo download.GERRIT = http://nexus.my-company.com/ >>local.properties
  echo download.MAVEN_CENTRAL = http://nexus.my-company.com/ >>local.properties

The local.properties file may be placed in the root of the gerrit repository being built, or in ~/.gerritcodereview/. The file in the root of the gerrit repository has precedence.

Building against unpublished Maven JARs

To build against unpublished Maven JARs, like gwtorm or PrologCafe, the custom JARs must be installed in the local Maven repository (mvn clean install) and maven_jar() must be updated to point to the MAVEN_LOCAL Maven repository for that artifact:

 maven_jar(
   name = 'gwtorm',
   artifact = 'gwtorm:gwtorm:42',
   repository = MAVEN_LOCAL,
 )

Building against artifacts from custom Maven repositories

To build against custom Maven repositories, two modes of operations are supported: with rewrite in local.properties and without.

Without rewrite the URL of custom Maven repository can be directly passed to the maven_jar() function:

  GERRIT_FORGE = 'http://gerritforge.com/snapshot'

  maven_jar(
    name = 'gitblit',
    artifact = 'com.gitblit:gitblit:1.4.0',
    sha1 = '1b130dbf5578ace37507430a4a523f6594bf34fa',
    repository = GERRIT_FORGE,
 )

When the custom URL has to be rewritten, then the same logic as with Gerrit known Maven repository is used: Repo name must be defined that matches an entry in local.properties file:

  download.GERRIT_FORGE = http://my.company.mirror/gerrit-forge

And corresponding WORKSPACE excerpt:

  GERRIT_FORGE = 'GERRIT_FORGE:'

  maven_jar(
    name = 'gitblit',
    artifact = 'com.gitblit:gitblit:1.4.0',
    sha1 = '1b130dbf5578ace37507430a4a523f6594bf34fa',
    repository = GERRIT_FORGE,
 )

To consume the JGit dependency from the development tree, edit lib/jgit/jgit.bzl setting LOCAL_JGIT_REPO to a directory holding a JGit repository.

To accelerate builds, several caches are activated per default:

  • ~/.gerritcodereview/bazel-cache/downloaded-artifacts

  • ~/.gerritcodereview/bazel-cache/repository

  • ~/.gerritcodereview/bazel-cache/cas

Currently none of these caches have a maximum size limit. See this bazel issue for details. Users should watch the cache sizes and clean them manually if necessary.

NPM Binaries

Parts of the PolyGerrit build require running NPM-based JavaScript programs as "binaries". We don’t attempt to resolve and download NPM dependencies at build time, but instead use pre-built bundles of the NPM binary along with all its dependencies. Some packages on registry.npmjs.org come with their dependencies bundled, but this is the exception rather than the rule. More commonly, to add a new binary to this list, you will need to bundle the binary yourself.

Note
 We can only use binaries that meet certain licensing requirements, and that do not include any native code.

Start by checking that the license and file types of the bundle are acceptable:

  gerrit_repo=/path/to/gerrit
  package=some-npm-package
  version=1.2.3

  npm install -g license-checker && \
  rm -rf /tmp/$package-$version && mkdir -p /tmp/$package-$version && \
  cd /tmp/$package-$version && \
  npm install $package@$version && \
  license-checker | grep licenses: | sort -u

This will output a list of the different licenses used by the package and all its transitive dependencies. We can only legally distribute a bundle via our storage bucket if the licenses allow us to do so. As long as all of the listed license are allowed by Google’s standards. Any by_exception_only, commercial, prohibited, or unlisted licenses are not allowed; otherwise, it is ok to distribute the source. If in doubt, contact a maintainer who is a Googler.

Next, check the file types:

  cd /tmp/$package-$version
  find . -type f | xargs file | grep -v 'ASCII\|UTF-8\|empty$'

If you see anything that looks like a native library or binary, then we can’t use the bundle.

If everything looks good, create the bundle, and note the SHA-1:

  $gerrit_repo/tools/js/npm_pack.py $package $version && \
  sha1sum $package-$version.tgz

This creates a file named $package-$version.tgz in your working directory.

Any project maintainer can upload this file to the storage bucket.

Finally, add the new binary to the build process:

  # WORKSPACE
  npm_binary(
      name = "some-npm-package",
      repository = GERRIT,
  )

  # lib/js/npm.bzl
  NPM_VERSIONS = {
    ...
    "some-npm-package": "1.2.3",
  }

  NPM_SHA1S = {
    ...
    "some-npm-package": "<sha1>",
  }

To use the binary from the Bazel build, you need to use the run_npm_binary.py wrapper script. For an example, see the use of crisper in tools/bzl/js.bzl.

Google Remote Build Support

The Bazel build can be used with Google’s Remote Build Execution.

This needs the following setup steps:

gcloud auth application-default login
gcloud services enable remotebuildexecution.googleapis.com  --project=${PROJECT}

Create a worker pool. The instances should have at least 4 CPUs each for adequate performance.

gcloud alpha remote-build-execution worker-pools create default \
    --project=${PROJECT} \
    --instance=default_instance \
    --worker-count=50 \
    --machine-type=n1-highcpu-4 \
    --disk-size=200

To use RBE, execute

bazel test --config=remote \
    --remote_instance_name=projects/${PROJECT}/instances/default_instance \
    javatests/...

Part of Gerrit Code Review