This doc describes how to set up a new builder on LUCI. It's focused on chromium builders, but parts may be applicable to other projects.
For a typical chromium builder using the chromium recipe, you'll need to acquire a host and then land three CLs:
chromium.star.//infra/config//tools/mb//testing/buildbotYour new builder's name should follow the chromium builder naming scheme.
We still use master names to group builders in a variety of places (even though buildbot itself is largely deprecated). FYI builders should use chromium.fyi, while other builders should mostly use chromium.$OS.
Note: If you're creating a try builder, its name should match the name of the CI builder it mirrors.
When you‘re setting up a new builder, you’ll need a host to run it. For CQ try bots, you‘ll likely need a large number of hosts to handle the load in parallel. For CI / waterfall builders or manually triggered try builders, you’ll typically only need a single host.
To acquire the hosts, please file a capacity bug (internal) and describe the amount needed, along with any specialized hardware that's required (e.g. mac hardware, attached mobile devices, a specific GPU, etc.).
Once your resource request has been approved and you‘ve obtained the hardware, you’ll need to associate it with your new builder in swarming. You can do so by modifying the relevant swarming instance's configuration.
This configuration is written in Starlark, and then used to generate Protobuf files which are also checked in to the repo. Chromium's configuration is in chromium.star (internal only).
If you're simply using a generic GCE bot, find the stanza corresponding to the OS and size that you want, and increment the number of bots allocated for that configuration. For example:
# os:Ubuntu-16.04, cpu:x86-64 chrome.gce_xenial( prefix = 'luci-chromium-ci-xenial-8', zone = 'us-central1-b', disk_gb = 400, lifetime = time.week, - amount = 20, + amount = 21, )
If you've been given a specific hostname, instead add an entry for your bot name to be mapped to that hostname. For example:
+ # os:Ubuntu-16.04, cpu:x86-64 + 'Linux Tests': 'swarm1234-c4',
Recipes tell your builder what to do. Many require some degree of per-builder configuration outside of the chromium repo, though the specifics vary. The recipe you use depends on what you want your builder to do.
For typical chromium compile and/or test builders, the chromium and chromium_trybot recipes should be sufficient.
To configure a chromium CI builder, you‘ll want to add a config block to the file in recipe_modules/chromium_tests corresponding to your new builder’s master name. The format is somewhat in flux and is not very consistent among the different masters, but something like this should suffice:
'your-new-builder': { 'chromium_config': 'chromium', 'gclient_config': 'chromium', 'chromium_apply_config': ['mb', 'ninja_confirm_noop'], 'chromium_config_kwargs': { 'BUILD_CONFIG': 'Release', # or 'Debug', as appropriate 'TARGET_BITS': 64, # or 32, for some mobile builders }, 'testing': { 'platform': '$PLATFORM', # one of 'mac', 'win', or 'linux' }, # Optional: where to upload test results. Valid values include: # 'public_server' for test-results.appspot.com # 'staging_server' for test-results-test.appspot.com # 'no_server' to disable upload 'test_results_config': 'public_server', # There are a variety of other options; most of them are either # unnecessary in most cases or are deprecated. If you think one # may be applicable, please reach out or ask your reviewer. }
For chromium try builders, you'll also want to set up mirroring. You can do so by adding your new try builder to trybots.py.
A typical entry will just reference the matching CI builder, e.g.:
TRYBOTS = freeze({ # ... 'tryserver.chromium.example': { 'builders': { # If you want to build and test the same targets as one # CI builder, you can just do this: 'your-new-builder': simple_bot({ 'mastername': 'chromium.example', 'buildername': 'your-new-builder' }), # If you want to build the same targets as one CI builder # but not test anything, you can do this: 'your-new-compile-builder': simple_bot({ 'mastername': 'chromium.example', 'buildername': 'your-new-builder', }, analyze_mode='compile'), # If you want to build and test the same targets as a builder/tester # CI pair, you can do this: 'your-new-tester': simple_bot({ 'mastername': 'chromium.example', 'buildername': 'your-new-builder', 'tester': 'your-new-tester', }), # If you want to mirror multiple try bots, please reach out. }, }, # ... })
Lastly, you need to configure a variety of things in the chromium repo. It's generally ok to land all of them in a single CL.
LUCI services used by chromium are configured in //infra/config.
The configuration is written in Starlark and used to generate Protobuf files which are also checked in to the repo.
Generating all of the LUCI services configuration files for the production builders is done by executing main.star or running lucicfg generate main.star.
Buildbucket is responsible for taking a build scheduled by a user or an agent and translating it into a swarming task. Its configuration includes things like:
Chromium‘s buildbucket Starlark configuration is here. Chromium’s generated buildbucket configuration is here. Buildbucket's configuration schema is here.
Each bucket has a corresponding .star file where the builders for the bucket are defined.
Most builders are defined using the builder function from builders.star (or some function that wraps it), which simplifies setting the most common dimensions and properties and provides a unified interface for setting module-level defaults.
A typical chromium builder won't need to configure much; module-level defaults apply values that are widely used for the bucket (e.g. bucket and executable).
Each master has a function (sometimes multiple) defined that can be used to define a builder that runs with that mastername and sets master-specific defaults. Find the block of builders defined using the appropriate function and add a new definition, which may be as simple as:
ci.linux_builder( name = '$BUILDER_NAME', )
You can generate the configuration files and then view the added entry in cr-buildbucket.cfg to make sure all properties and dimensions are set as expected and adjust your definition as necessary.
Milo is responsible for displaying builders and build histories on a set of consoles. Its configuration includes the definitions of those consoles.
Chromium‘s milo Starlark configuration is here. Chromium’s generated milo configuration is here. Milo's configuration schema is here.
Each console has a corresponding .star file that defines the console.
A typical chromium builder should be added to one or two consoles at most: one corresponding to its master, and possibly the main console.
The sequence of CI builds for a builder corresponds to a linear history of revisions in the repository, and the console takes advantage of that, allowing you to compare what revisions are in what builds for different builders in the console.
luci.console_view( name = '$MASTER_NAME', ... entries = [ ... luci.console_view( builder = '$BUCKET_NAME/$BUILDER_NAME', # A builder's category is a pipe-delimited list of strings # that determines how a builder is grouped on a console page. # N>=0 category = '$GROUP1|$GROUP2|...|$GROUPN', # A builder's short name is a string up to three characters # long that lets someone uniquely identify it among builders # in the same category. short_name = '$SHORT_NAME', ), ... ], ),
Both category and short_name can be omitted, but is strongly recommended that all entries include short name.
The sequence of try builders for a builder does not correspond to a linear history of revisions. Consequently, the interface for the consoles is different, as is the method of defining the console.
luci.list_view( name = '$MASTER_NAME', entries = [ ... '$BUCKET_NAME/$BUILDER_NAME', ... ], ),
The scheduler is responsible for triggering CI / waterfall builders.
Chromium‘s scheduler Starlark configuration is intermixed with the builder definitions. Chromium’s generated scheduler configuration is here. Scheduler's configuration schema is here.
To trigger builders when changes are landed on a repo, a poller needs to be defined. The poller defines the repo and refs to watch and triggers builders when changes land on one of the watched refs.
Pollers are already defined for all of the active refs within chromium/src. The modules for the ci bucket and its release branch counterparts are written such that builders will be triggered by the appropriate poller by default. Setting the triggered_by field on a builder will disable this default behavior.
Builders that will be triggered by other builders (e.g. a builder compiles tests and then triggers another builder to actually run the tests) call this out in their own definition by setting the triggered_by field. For builders in the ci bucket and its release branch counterparts, this will disable the default behavior of being triggered by the poller.
ci.linux_builder( name = '$BUILDER_NAME', triggered_by = ['$PARENT_BUILDER_NAME'], )
Builders that need to run regularly but not in response to landed code can be scheduled using the schedule field in their definition. For builders in the ci bucket and its release branch counterparts, the triggered_by field should be set to an empty list to disable the default behavior of being triggered by the poller. See the documentation of the schedule field in the Job message in the scheduler schema.
ci.builder( name = '$BUILDER_NAME', schedule = 'with 10m interval', triggered_by = [], )
The build and test configurations used by the main chromium and chromium_trybot recipes are stored src-side:
Build configuration: the gn configuration used by chromium recipe builders is handled by MB. MB's configuration is documented here. You only need to modify it if your new builder will be compiling.
Test configuration: the test configuration used by chromium recipe builders is in a group of .pyl and derived .json files in //testing/buildbot. The format is described here.
If you‘re in need of further assistance, if you’re not sure about one or more steps, or if you found this documentation lacking, please reach out to infra-dev@chromium.org or file a bug!