# Continuous build and test infrastructure for Chromium for iOS See the [instructions] for how to check out and build Chromium for iOS. The Chromium projects use buildbot for continuous integration. This doc starts with an overview of the system, then gives detailed explanations about each part. [TOC] ## Overview Commits are made using the [commit queue], which triggers a series of try jobs to compile and test the proposed patch against Chromium tip of tree before actually making the commit. If the try jobs succeed the patch is committed. A newly committed change triggers the builders (or "bots") to compile and test the change again. ## Bots Bots are slaves attached to a buildbot master (or "waterfall"). A buildbot master is a server which polls for commits to a repository and triggers workers to compile and test new commits whenever they are detected. [chromium.mac] is the main waterfall for Mac desktop and iOS. [tryserver.chromium.mac] serves as the try server for Mac desktop and iOS. The bots know how to check out a given revision of Chromium, compile, and test. ### Code location #### Master configs The masters are configured in [tools/build], a separate repository which contains various infra-related scripts. #### Pollers [chromium.mac] uses a `GitilesPoller` which polls the Chromium repository for new commits using the [gitiles] interface. When a new commit is detected, the bots are triggered. #### Recipes The bots run [recipes], which are scripts that specify their sequence of steps located in [tools/build]. An iOS-specific [recipe module] contains common functionality that the various [iOS recipes] use. #### Configs Because the recipes live in another repository, changes to the recipes don't go through the Chromium [commit queue] and aren't tested on the [try server]. In order to allow bot changes to be tested by the commit queue, the recipes for iOS are generic instead of bot-specific, and rely on configuration files which live in master-specific JSON config files located in [src/ios/build/bots]. These configs define the `gn_args` to use during compilation as well as the tests to run. #### Scripts The [test runner] is the script which installs and runs the tests, interprets the results, and collects any files emitted by the test ("test data"). It can be found in [src/ios/build/bots/scripts], which means changes to the test runner can be tested on the [try server]. ### Compiling with goma Goma is the distributed build system used by Chromium. It reduces compilation time by avoiding recompilation of objects which have already been compiled elsewhere. ### Testing with swarming Tests run on [swarming], a distributed test system used by Chromium. After compilation, configured tests will be zipped up along with their necessary dependencies ("isolated") and sent to the [swarming server] for execution. The server issues tasks to its attached workers for execution. The bots themselves don't run any tests, they trigger tests to be run remotely on the swarming server, then wait and display the results. This allows multiple tests to be executed in parallel. ## Try bots Try bots are bots which test proposed patches which are not yet committed. Request [try job access] in order to trigger try jobs against your patch. The relevant try bots for an iOS patch are `ios-device` and `ios-simulator`. These bots can be found on the Mac-specific [try server]. A try job is said to succeed when the build passes (i.e. when the bot successfully compiles and tests the patch). `ios-device` compiles for the iOS device architecture (ARM) and runs no tests. A build is considered successful so long as compilation is successful. `ios-simulator` compiles for the iOS simulator architecture (x86), and runs tests in the iOS [simulator]. A build is considered successful when both compilation and all configured tests succeed. `ios-device` and `ios-simulator` both compile using the version of [clang] defined by the `CLANG_REVISION` in the Chromium tree. ### Scheduling try jobs using buildbucket Triggering a try job and collecting its results is accomplished using [buildbucket]. The service allows for build requests to be put into buckets. A request in this context is a set of properties indicating things such as where to get the patch. The try bots are set up to poll a particular bucket for build requests which they execute and post the results of. ### Compiling with the analyzer In addition to goma, the try bots use another time-saving mechanism called the [analyzer] to determine the subset of compilation targets affected by the patch that need to be compiled in order to run the affected tests. If a patch is determined not to affect a certain test target, compilation and execution of the test target will be skipped. ## Configuring the bots See the [configs code location](#Configs) for where to find the config files for the bots. The config files are JSON which describe how the bot should compile and which tests it should run. The config files are located in the configs directory. The configs directory contains a named directory for each master. For example: ```shell $ ls ios/build/bots OWNERS scripts tests chromium.fyi chromium.mac ``` In this case, configs are defined for iOS bots on [chromium.fyi] and [chromium.mac]. Inside each master-specific directory are JSON config files named after each bot. For example: ```shell $ ls ios/build/bots/chromium.mac ios-device.json ios-simulator.json ``` The `ios-device` bot on [chromium.mac] will read its configuration from `chromium.mac/ios-device.json` in the configs directory. ### Example ```json { "comments": [ "Sample config for a bot." ], "gn_args": [ "is_debug=true", "target_cpu=\"x64\"" ], "tests": [ { "app": "ios_chrome_unittests", "device type": "iPhone 5s", "os": "11.0", "xcode build version": "9A235" } ] } ``` The `comments` key is optional and defines a list of strings which can be used to annotate the config. You may want to explain why the bot exists and what it's doing, particularly if there are extensive and atypical `gn_args`. The `gn_args` key is a required list of arguments to pass to [GN] to generate the build files. Two GN args are required, `is_debug` and `target_cpu`. Use `is_debug` to define whether to compile for Debug or Release, and `target_cpu` to define whether to compile for x86, x64, arm, or arm64. The iOS bots typically perform Debug builds for x86 and x64, and Release builds for arm and arm64. An x86/x64 build can only be tested on the [iOS simulator], while an arm/arm64 build can only be tested on a physical device. Since Chromium for iOS is shipped as a [universal binary], it's also fairly common to set `additional_target_cpus`. For simulator builds, we typically set: ```json "gn_args": [ "additional_target_cpus=[\"x86\"]", "is_debug=true", "target_cpu=\"x64\"" ] ``` This builds universal binaries which run in 32-bit mode on 32-bit simulators and 64-bit mode on 64-bit simulators. For device builds we typically set: ```json "gn_args": [ "additional_target_cpus=[\"arm\"]", "is_debug=false", "target_cpu=\"arm64\"" ] ``` In order to build universal binaries which run in 32-bit mode on 32-bit devices and 64-bit mode on 64-bit devices. The `tests` key is an optional list of dictionaries defining tests to run. There are two types of test dictionary, `app` and `include`. An `app` dict defines a specific compiled app to run, for example: ```json "tests": [ { "app": "ios_chrome_unittests", "device type": "iPhone 5s", "os": "11.0", "xcode build version": "9A235" } ] ``` This dict says to run `ios_chrome_unittests` on an `iPhone 5s` running iOS `11.0` using Xcode build version `9A235`. A test dict may optionally define a list of `test args`, which are arguments to pass directly to the test on the command line, and it may define a boolean value `xctest` to indicate whether the test is an [xctest] \(default if unspecified is `false`\). For example: ```json "tests": [ { "app": "ios_chrome_unittests", "device type": "iPhone 5s", "os": "11.0", "test args": [ "--foo", "--bar" ], "xcode build version": "9A235" }, { "app": "ios_chrome_integration_egtests", "device type": "iPhone 5s", "os": "11.0", "xcode build version": "9A235", "xctest": true } ] ``` This defines two tests to run, first `ios_chrome_unittests` will be run with `--foo` and `--bar` passed directly to the test on the command line. Next, `ios_chrome_integration_egtests` will be run as an xctest. `"xctest": true` must be specified for all xctests, it is an error to try and launch an xctest as a regular test. An `include` dict defines a list of tests to import from the `tests` subdirectory in the configs directory. For example: ```json "tests": [ { "include": "common_tests.json", "device type": "iPhone 5s", "os": "11.0", "xcode build version": "9A235" } ] ``` This dict says to import the list of tests from the `tests` subdirectory and run each one on an `iPhone 5s` running iOS `11.0` using Xcode `9A235`. Here's what `common_tests.json` might look like: ```json "tests": [ { "app": "ios_chrome_unittests" }, { "app": "ios_net_unittests" }, { "app": "ios_web_unittests" }, ] ``` Includes may contain other keys besides `app` which can then be omitted in the bot config. For example if `common_tests.json` specifies: ```json "tests": [ { "app": "ios_chrome_integration_egtests", "xctest": true, "xcode build version": "9A235" } ] ``` Then the bot config may omit the `xctest` or `xcode build version` keys, for example: ```json { "comments": [ "Sample config for a bot." ], "gn_args": [ "is_debug=true", "target_cpu=\"x64\"" ], "tests": [ { "include": "common_tests.json", "device type": "iPhone 5s", "os": "11.0" } ] } ``` Includes are not recursive, so `common_tests.json` may not itself include any `include` dicts. Some keywords such as `xcode build version` can also be set globally per build: ```json { "comments": [ "Sample config for a bot." ], "gn_args": [ "is_debug=true", "target_cpu=\"x64\"" ], "xcode build version": "9A235", "tests": [ { "app": "ios_chrome_integration_egtests", "device type": "iPhone 5s", "os": "11.0" } ] } ``` ### Uploading compiled artifacts from a bot A bot may be configured to upload compiled artifacts. This is defined by the `upload` key. For example: ```json { "comments": [ "Sample config for a bot which uploads artifacts." ], "gn_args": [ "is_debug=true", "target_cpu=\"x64\"" ], "upload": [ { "artifact": "Chromium.breakpad", "bucket": "my-gcs-bucket", }, { "artifact": "Chromium.app", "bucket": "my-gcs-bucket", "compress": true, }, { "artifact": "Chromium.breakpad", "symupload": "https://clients2.google.com/cr/symbol", } ] } ``` After compilation, the bot will upload three artifacts. First the `Chromium.breakpad` symbols will be uploaded to `gs://my-gcs-bucket///Chromium.breakpad`. Next `Chromium.app` will be tarred, gzipped, and uploaded to `gs://my-gcs-bucket///Chromium.tar.gz`. Finally the `Chromium.breakpad` symbols will be uploaded to the [breakpad] crash reporting server where they can be used to symbolicate stack traces. If `artifact` is a directory, you must specify `"compress": true`. [analyzer]: ../../tools/mb [breakpad]: https://chromium.googlesource.com/breakpad/breakpad [buildbucket]: https://cr-buildbucket.appspot.com [chromium.fyi]: https://build.chromium.org/p/chromium.fyi/waterfall [chromium.mac]: https://build.chromium.org/p/chromium.mac [clang]: ../../tools/clang [commit queue]: https://dev.chromium.org/developers/testing/commit-queue [gitiles]: https://gerrit.googlesource.com/gitiles [GN]: ../../tools/gn [instructions]: ./build_instructions.md [iOS recipes]: https://chromium.googlesource.com/chromium/tools/build/+/main/scripts/slave/recipes/ios [iOS simulator]: ../../testing/iossim [recipe module]: https://chromium.googlesource.com/chromium/tools/build/+/main/scripts/slave/recipe_modules/ios [recipes]: https://chromium.googlesource.com/infra/infra/+/HEAD/doc/users/recipes.md [simulator]: https://developer.apple.com/library/content/documentation/IDEs/Conceptual/iOS_Simulator_Guide/Introduction/Introduction.html [src/ios/build/bots]: ../../ios/build/bots [src/ios/build/bots/scripts]: ../../ios/build/bots/scripts [swarming]: https://chromium.googlesource.com/infra/luci/luci-py/+/main/appengine/swarming/ [swarming server]: https://chromium-swarm.appspot.com [test runner]: ../../ios/build/bots/scripts/test_runner.py [tools/build]: https://chromium.googlesource.com/chromium/tools/build [try job access]: https://www.chromium.org/getting-involved/become-a-committer#TOC-Try-job-access [try server]: https://build.chromium.org/p/tryserver.chromium.mac/waterfall [tryserver.chromium.mac]: https://build.chromium.org/p/tryserver.chromium.mac/waterfall [universal binary]: https://en.wikipedia.org/wiki/Universal_binary [xctest]: https://developer.apple.com/reference/xctest