= Gerrit Code Review - Building with Bazel

[[installation]]
== Installation

You need to use Python (2 or 3), Java 8, and Node.js for building gerrit.

You can install Bazel from the bazel.io:
https://www.bazel.io/versions/master/docs/install.html

Alternatively use Bazelisk to use the latest supported Bazel version on
different stable branches: https://github.com/bazelbuild/bazelisk.

[[build]]
== Building on the Command Line

=== Gerrit Development WAR File

To build the Gerrit web application that includes the GWT UI and 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
----

[[release]]
=== Gerrit Release WAR File

To build the Gerrit web application that includes the GWT UI, the
PolyGerrit UI 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 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 //...
----


[[IDEs]]
== Using an IDE.

=== IntelliJ

The Gerrit build works with Bazel's link:https://ij.bazel.io[IntelliJ plugin].
Please follow the instructions on <<dev-intellij#,IntelliJ Setup>>.

=== Eclipse

==== Generating the Eclipse Project

Create the Eclipse project:

----
  tools/eclipse/project.py
----

and then follow the link:dev-eclipse.html#setup[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 link:https://ij.bazel.io[IntelliJ plugin].

[[documentation]]
=== 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
----

[[tests]]
== 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 //gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/api/change:api_change
----

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

----
  bazel test //gerrit-acceptance-tests/src/test/java/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=DISABLE_CHANGE_REVIEW_DB //...
----

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
* notedb
* pgm
* rest
* server
* ssh

[[elasticsearch]]
=== Elasticsearch

Successfully running the Elasticsearch tests requires Docker, and
may require setting the local
link:https://www.elastic.co/guide/en/elasticsearch/reference/current/vm-max-map-count.html[virtual memory].

If Docker is not available, the Elasticsearch tests will be skipped.
Note that Bazel currently does not show
link:https://github.com/bazelbuild/bazel/issues/3476[the skipped tests].

== 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:

[source,python]
----
 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:

[source,python]
----
  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:

[source,python]
----
  GERRIT_FORGE = 'GERRIT_FORGE:'

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

[[consume-jgit-from-development-tree]]

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.

[[bazel-local-caches]]

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
link:https://github.com/bazelbuild/bazel/issues/5139[this bazel issue] for
details. Users should watch the cache sizes and clean them manually if
necessary.


[[RBE]]
== 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/...
```


GERRIT
------
Part of link:index.html[Gerrit Code Review]

SEARCHBOX
---------