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This commit helps reduce clutter on the navigation sidebar. Creates new directories and moves relevant files into them. Modifies index.rst, symlinks, and image paths accordingly. This commit also enables expandable/collapsible navigation items, renames files in docs/development and docs/production, modifies /tools/test-documentation so that it overrides a theme setting, Also updates links to other docs, file paths in the codebase that point to developer documents, and files that should be excluded from lint tests. Note that this commit does not update direct links to zulip.readthedocs.io in the codebase; those will be resolved in an upcoming follow-up commit (it'll be easier to verify all the links once this is merged and ReadTheDocs is updated). Fixes #5265.
118 lines
5.1 KiB
Markdown
118 lines
5.1 KiB
Markdown
# Travis CI
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The Zulip server uses [Travis CI](https://travis-ci.org/) for its
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continuous integration. This page documents useful tools and tips to
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know about when using Travis CI and debugging issues with it.
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## Goals
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The overall goal of our Travis CI setup is to avoid regressions and
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minimize the total time spent debugging Zulip. We do that by trying
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to catch as many possible future bugs as possible, while minimizing
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both latency and false positives, both of which can waste a lot of
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developer time. There are a few implications of this overall goal:
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* If a test is failing nondeterministically in Travis CI, we consider
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that to be an urgent problem.
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* If the tests become a lot slower, that is also an urgent problem.
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* Everything we do in CI should also have a way to run it quickly
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(under 1 minute, preferably under 3 seconds), in order to iterate fast
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in development. Except when working on the Travis CI configuration
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itself, a developer should never have to repeatedly wait 10 minutes
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for a full Travis run to iteratively debug something.
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## Configuration
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The main Travis configuration file is
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[.travis.yml](https://github.com/zulip/zulip/blob/master/.travis.yml).
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The specific test suites we have are listed in the `matrix` section,
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which has a matrix of Python versions and test suites (`$TEST_SUITE`).
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We've configured it to use a few helper scripts for each job:
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* `tools/travis/setup-$TEST_SUITE`: The script that sets up the test
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environment for that suite (E.g., installing dependencies).
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* For the backend and frontend suites, this is a thin wrapper around
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`tools/provision`, aka the development environment provision script.
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* For the production suite, this is a more complicated process
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because of all the packages Travis installs. See the comments in
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`tools/travis/setup-production` for details.
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* `tools/travis/$TEST_SUITE`: The script that runs the actual test
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suite.
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The main purpose of the distinction between the two is that if the
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`setup-backend` job fails, Travis CI will report it as the suite
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having "Errored" (grey in their emails), whereas if the `backend` job
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fails, it'll be reported as "Failed" failure (red in their emails).
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Note that Travis CI's web UI seems to make no visual distinction
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between these.
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An important detail is that Travis CI will by default hide most phases
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other than the actual test; you can see this easily by looking at the
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line numbers in the Travis CI output. There are actually a bunch of
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phases (e.g. the project's setup job, downloading caches near the
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beginning, uploading caches at the end, etc.), and if you're debugging
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our configuration, you'll want to look at these closely.
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## Useful debugging tips and tools
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* Zulip uses the `ts` tool to log the current time on every line of
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the output in our Travis CI scripts. You can use this output to
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determine which steps are actually consuming a lot of time.
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* For performance issues,
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[this statistics tool](https://scribu.github.io/travis-stats/#zulip/zulip/master)
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can give you test runtime history data that can help with
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determining when a performance issue was introduced and whether it
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was fixed. Note you need to click the "Run" button for it to do
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anything.
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* You can [sign up your personal repo for Travis CI][travis-fork] so
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that every remote branch you push will be tested, which can be
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helpful when debugging something complicated.
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[travis-fork]: ../contributing/git-guide.html#step-3-configure-travis-ci-continuous-integration
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## Performance optimizations
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### Caching
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An important element of making Travis CI perform effectively is
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caching the provisioning of a Zulip development environment. In
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particular, we cache the following across jobs:
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* Python virtualenvs
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* node_modules directories
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* Built/downloaded emoji sprite sheets and data
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This has a huge impact on the performance of running tests in Travis
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CI; without these caches, the average test time would be several times
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longer.
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We have designed these caches carefully (they are also used in
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production and the Zulip development environment) to ensure that each
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is named by a hash of its dependencies, so Zulip should always be
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using the same version of dependencies it would have used had the
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cache not existed. In practice, bugs are always possible, so be
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mindful of this possibility.
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A consequence of this caching is that test jobs for branches which
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modify `package.json`, `requirements/`, and other key dependencies
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will be significantly slower than normal, because they won't get to
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benefit from the cache.
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### Uninstalling packages
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In the production suite, we run `apt-get upgrade` at some point
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(effectively, because the Zulip installer does). This carries a huge
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performance cost in Travis CI, because (1) they don't keep their test
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systems up to date and (2) literally everything is installed in their
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build workers (e.g. several copies of Postgres, Java, MySQL, etc.).
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In order to make Zulip's tests performance reasonably well, we
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uninstall (or mark with `apt-mark hold`) many of these dependencies
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that are irrelevant to Zulip in
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[`tools/travis/setup-production`][setup-production].
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[setup-production]: https://github.com/zulip/zulip/blob/master/tools/travis/setup-production
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