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Latest commit df98932 Jan 24, 2017 @brson Prefetch messages

Crater - The Rust crate tester

This is a tool for testing builds of the Rust compiler against massive numbers of Rust crates.

It is in a very rough state and the official deployment is presently accessible by invitation only.

Getting started

Clone the repo and cd to the 'rs' directory.

$ git clone
$ cd taskcluster-crater/rs

In this directory create crater-cli-config.json. It looks like this:

    "server_url": "",
    "username": "your_username",
    "auth_token": "your_token"

Get your credentials from brson.

Test your configuration:

$ cargo run --bin crater-cli self-test

If it says 'self-test succeeded' you've authenticated. Now you can cause some havok.

There are three steps to running crater:

  1. Build two custom toolchains (optional).
  2. Build crates against two toolchains.
  3. Run a 'comparison' report.

Step 1 - build two custom toolchains

Skip this step if you are just testing a compiler from an official release channel.

To test a revision of the compiler that has not yet been merged into master you will need to upload the branch to GitHub, then ask crater to build it for you. You will need two commit shas: the most recent commit on master that you are working off of, and the 'merge-base' with upstream master (the most recent commit your branch shares with master). Record these somewhere; you'll need them later. In the remaining examples these will be refered to as $SHA1 and $SHA2, and the repo address as $REPO.

Build the toolchains:

$ cargo run --bin crater-cli custom-build $REPO $SHA1
$ cargo run --bin crater-cli custom-build $REPO $SHA2

These will launch the builds, which will take an hour or two to complete. Each of the above commands will print an 'inspector link', a link to the TaskCluster page for that build. Check back on these links periodically until they are both finished. It will take 1-2 hours.

Once these builds are done you can start testing crates.

Note: if you are just testing official builds then identify the toolchains using multirust-style 'toolchain specs', e.g. 'nightly-2015-06-06'. Always test compilers from the archives and not straight from the release channel (e.g. 'nightly') since the release channel compilers change regularly and the results won't make sense down the road if we do historical analysis.

Step 2 - build lots of crates

As before, we're going to ask Crater to run some builds, then wait a few hours while those builds complete.

$ cargo run --bin crater-cli crate-build $SHA1
$ cargo run --bin crater-cli crate-build $SHA2

Both of these commands will print a ton of inspector links. You'll probably just want to ignore them since they are not worth monitoring individually. Instead, just wait two hours, then proceed to step 3.

This command will take a long time to complete, displaying no progress. Give it a few minutes.

You might also watch the status page for the TaskCluster AWS provisioner, waiting for the number of builds on the 'crater' workers to drop back to zero before proceeding to step 3.

Step 3 - run the report

Now you can ask for a 'comparison' report:

$ cargo run --bin crater-cli report comparison $SHA1 $SHA2

It will report statuses for some number of crates. Knowing whether the report is 'done' and the crates have built correctly is not simple - generally, if I see the number of known statuses is in the right ballpark and the number of unknown statuses is minimal (maybe 30-40) then I consider the coverage sufficient.

If the numbers look wrong then either the builds are not finished, something went wrong internally to the cobbled-together distributed system that is Crater, or you've issued one of the commands incorrectly.

If the numbers are weird then you might ask for a report on a single toolchain at a time, which can tell you if you got the commands for one or the other incorrect:

$ cargo run --bin crater-cli report toolchain $SHA1

OK, that's all I can tell you for now. Good luck. Sorry it's so rough.

Older docs

This is a collection of node.js tools for testing large numbers of Rust crates against arbitrary builds of Rust in parallel.

It currently consistents of a variety of modules for accessing services, scheduling builds, monitoring status, analysis and reporting, as well as several command-line utilities for interacting with the system.

Note: currently Crater is unusable without a local installation and a number of credentials. Eventually it will be deployed somewhere with a more convenient interface.

Crater has a number of service dependencies, that make it difficult to set up:

  • TaskCluster for coordinating builds, and specifically Mozilla's instance of TaskCluster. Requires credentials.
  • Pulse, Mozilla's AMQP service, used by TaskCluster. Requires credentials.
  • The index. A git repo containing metadata about registered crate revisions for
  • The API. For downloading metadata
  • The Rust distribution S3 bucket. For downloading crates and builds.
  • A PostgreSQL database for storing results (Amazon RDS). Requires credentials.


  • crate-index.js - Functions relating to and the crates.
  • rust-dist.js - Access to Rust release channels.
  • crater-db.js - Domain specific storage abstractions over a SQL database.
  • reports.js - Report generation.
  • scheduler.js - Logic for scheduling builds.
  • monitor.js - Deamon that monitors the pulse queue for events.
  • schedule-tasks.js - CLI tool for scheduling builds.
  • print-report.js - CLI tool for creating reports.
  • crate-util.js - Common stuff.
  • test.js - Unit tests.

CLI tools

Scheduling a test the 20 most popular crates againast a specific toolchain:

$ nodejs schedule-tasks.js nightly-2015-03-01 --top 20 --most-recent-only

Running the result monitoring and storage service:

$ nodejs monitor.js

monitor.js will store the results in a database for later analysis.

Running reports:

$ nodejs print-report.js comparison nightly-2015-03-01 nightly-2015-03-02


The files "tc-credentials.json", "pulse-credentials.json", and "pg-credentials.json" must be in the current directory.

tc-credentials.json looks like yon:

  "clientId": "...",
  "accessToken": "...",
  "certificate": { ... }

The values can be obtained from

pulse-credentials.json looks like yon:

  "username": "...",
  "password": "..."

The values can be obtained from

PostgreSQL setup

monitor.js and test.js needs a PostgreSQL user, which can be set up with

sudo -u postgres createuser $USER

You'll need a test database and a production database.

sudo -u postgres createdb crater-test -O $USER
sudo -u postgres createdb crater -O $USER

And create a password for the user

psql -c "\password" -U $USER -d crater

The credentials need to be in pg-credentials.js:

  "username": "...",
  "password": "...",
  "host": "...",
  "port": 5432


$ npm test

You'll need to have a 'crater-test' database configured locally, for user 'crater-test' with password 'crater-test'.

Creating the docker image

$ docker build -t brson/crater:1 .
$ docker push brson/crater

Future work

  • Use task graphs that mirror the crate dependency structure.
  • Custom builds
  • Only create tasks for build_results we don't have yet, unless --all is passed
  • REST service
  • HTML frontend
  • CLI <-> REST frontend
  • Use customized docker containers to avoid huge dls
  • Fix urls in pop report
  • Crate DAGs with stability coloring
  • Add analysis of feature usage
  • Toolchain build status
  • projects, focus on prod users
  • nightly breakage dashboard

11:53 if we had a massive dashboard showing, for every crate in (and eventually other sources): 11:54 - most recent stable release 11:54 - most recent nightly release 11:54 - when was it last tested