Auto-tools/Projects/Pulse
Mozilla Pulse
Mozilla currently has a ton of different systems that are inter-connected via polling, screen scraping, email, and other brittle methods. To make their lives easier community members often build tools on top of this house of cards, adding yet another level of scraping and polling. Many systems don't even export important data for others to scrape and use, preventing better tools from being written.
The goal of Pulse is to eliminate polling and add visibility into all aspects of Mozilla and its systems. This allows more robust, dynamic, and informative tools.
We have a discussion forum available via the standard trio of USENET newsgroup, mailing list, and Google Group.
File bugs under Webtools :: Pulse.
Also see the Pulse Inspector web app, which displays Pulse messages in real time, and the (manually updated) list of Pulse exchanges.
System Description
Pulse isn't any one thing. At its heart, it is a RabbitMQ system with a particular configuration and a set of conventions for using it along with a management tool, PulseGuardian, to make Pulse as automated and self-serve as possible. Pulse follows the pub-sub pattern, in which publishers send messages to topic exchanges, and consumers create queues bound to these exchanges in order to subscribe to the publishers' messages. The mozillapulse Python package provides classes for existing publishers, consumers, and messages so you can quickly build Pulse applications.
Contributing
Here is a the list of open, unassigned mentored Pulse bugs to see how you can contribute!
3 Total; 3 Open (100%); 0 Resolved (0%); 0 Verified (0%);
Once you have your feet wet and are ready to take on a more involved project, here is a list of all current Pulse bugs:
16 Total; 16 Open (100%); 0 Resolved (0%); 0 Verified (0%);
To set up a local system for development, see the HACKING.md file included in the mozillapulse source.
For mentored bugs, we use the User Story to provide a link back to this page, as well as any extra information for contributors, such as required knowledge/learnings. The basic text for mentored bugs should be "This is a mentored Pulse bug. For general information on Pulse, see https://wiki.mozilla.org/Auto-tools/Projects/Pulse, which includes a section on Contributing." An example of extra text is "This bug also requires you to have a working mail server."
Status
At the moment, only BuildBot messages (BuildMessage, TestMessage) and SimpleBugMessages are being published to Pulse.
There used to be two other publishers, which have been disabled:
- HgPublisher: the original shim "crashed on various occasions, in particular file additions/removals/renames and merges made it go funky."
- bug 1022701 on file to fix and re-enable.
- BugzillaPublisher: this produced too much traffic for the original prototype system, and for security reasons it could publish only changes to public bugs, making it of questionable value. The SimpleBugzillaPublisher is a lightweight replacement that publishes only bug ID and change time, but for all bugs, public or otherwise.
Consuming buildbot messages
There are two ways to consume messages published by buildbot. The most direct way, which requires the most knowledge about buildbot, is using the BuildConsumer in mozillapulse. This consumer has access to all the native buildbot messages, and therefore offers the most flexibility.
The disadvantage of using the BuildConsumer is that you need to spend time understanding what messages buildbot publishes to pulse, and how these can vary, and associate particular messages with what you're trying to accomplish. The format of buildbot messages is undocumented, and can change without warning, which makes services based on the BuildConsumer potentially fragile.
To address some of these disadvantages, a translator is run against the BuildConsumer (the pulsetranslator) which re-publishes a subset of buildbot messages to a NormalizedBuild exchange, which are available using the NormalizedBuildConsumer of mozillapulse. The content of these messages is simplified and normalized, making it easier to consume without the need to have a thorough understanding of how buildbot publishes messages to pulse. The re-published messages also protect consumers against some changes to the pulse stream, although significant enough changes will likely break the pulse translator as well as direct users of BuildConsumer.
Another advantage of the NormalizedBuildConsumer is that it will only publish messages for a given build or test job after the logs for that job are available; using the BuildConsumer directly can result in the reception of messages for a build before the build artifacts are available, which can cause problems in consumers if they don't explicitly guard against this problem.
Generally speaking, consumers that wish to be notified when specific build or test jobs are completed should use the NormalizedBuildConsumer; consumers that need direct access to the buildbot pulse stream or are looking for non-specific jobs (such as all jobs belonging to a particular commit) should probably use the BuildConsumer.
Technology used
- The message broker used is RabbitMQ.
- Protocol used to talk to the broker is AMQP.
- Messages are in JSON.
- For the Python mozillapulse package, the underlying library currently used to talk AMQP is Kombu.
Road Map
See the prioritized bug list for all open issues.
Website
- bug 1017957 Merge above in with PulseGuardian; no point in having two websites.
- Indicate current Pulse status (at least just up/down).
- (Maybe) Display published messages on the Pulse website (mostly decorative but also an example of use in the browser).
Management
- (Almost done!) Intelligently handle queues that start filling up.
- See PulseGuardian.
Security
- [DONE] Enable SSL.
- bug 1013980 Enable SSL by default in clients.
- Close non-SSL port eventually?
- Move to a tighter permission model. See the Security Model section below.
Shims
- Re-enable hg shim?
- Add git shim?
- Other shims?
Other
- Upgrade RabbitMQ to latest 3.x version (ideally with zero downtime).
- Enable STOMP or some other method of accessing Pulse via the browser.
- Create a JavaScript library along the lines of the mozillapulse Python package.
Security Model
In order to have a reliable, well behaved system, the following assertions will need to be true.
- All users, publishers and consumers alike, must have their own accounts (no guest/public users).
- Only publishers should be able to declare exchanges.
- Only the publisher user account associated with a particular vhost should be allowed to publish messages to exchanges in the vhost. In other words, exactly one user account should be allowed to publish messages within a given vhost.
- Only the user that created a particular queue should be allowed to consume from it.
Since exchange and queue permissions go together, we'll need exchange and queue naming conventions mixed with restrictive permissions. Each user will be restricted to a particular exchange and queue naming prefix. Many users will be either consumers or publishers, but for simplicity, each user can do both. Users will have full permissions on "^exchange/<username>/.*$" and "^queue/<username>/.*$". They will also have read permissions to exchange/*. This will both prevent users from writing to other users' exchanges as well as prevent them from consuming from other users' queues. For convenience, if a consumer creates a nondurable queue, mozillapulse can assign a random suffix to the user's standard queue name prefix, i.e. queue/<username>/<random string>, since the user wouldn't be able to create nor access a completely random server-assigned name.
Note that this doesn't prevent a consumer from creating an exchange named as a queue, since the permission model doesn't distinguish between queues and exchanges, and consumers need the ability to create queues. This is not particularly problematic, since no one would have permission to use that exchange.
With this security model, we technically don't really need vhosts, since the names of the queues and exchanges the users can use are so specific. There may still be a benefit in allowing apps to use the same queue name for different exchanges, though, which would be possible if each exchange had its own vhost. The downside is that you cannot specify "all vhosts" when setting a user's permissions, so they would either have to list all vhosts they want to use when creating the user in PulseGuardian, and be able to update that list later, or PulseGuardian or some other app would have to automatically add new permissions to all users when a vhost is created.
Admin Procedures
These should largely become obsolete when PulseGuardian is deployed.
- When a queue becomes stuck, you can use the Admin UI to kill it. Try to ping the queue owner first before killing if possible.
- More than half of the queues are QA related (whimboo)
- pulsetranslator service, which normalizes buildbot messages, is currently running on pulsetranslator.ateam.phx1.mozilla.com and may need to be reset from time to time.
- logparser service, used by Orange Factor, runs on orangefactor1.dmz.phx1.mozilla.com
More reading
LegNeato wrote several blog posts on Pulse as he was building it. They contain some more background if you're really interested. They are linked below, in chronological order.
- Mozilla Pulse and RabbitMQ
- Push notifications for Bugzilla
- This idea has been shelved for the time being, both due to security issues and performance. See BMO/ChangeNotificationSystem for an alternative.
- bugzilla-amqp is now buzgilla-push, supports the STOMP protocol
- See above note. Just keeping these links for interest's sake.
- What’s up with Pulse?
- GitHub AMQP integration service hook live!
- Tangentially related to Pulse.
- Lots of Pulse changes, out of prototype mode this week!
- Another update on Pulse