Keeper of the statuses
Travis Hub is the application that, in the life-cycle of accepting, evaluating, and executing a build request, sits in the fifth position, next to Travis Logs.
In short Hub deals with updates to the job and build status coming in from the workers, while Logs deals with collecting build log output from them.
Once a build request has been:
- accepted by Listener,
- approved and configured by Gatekeeper,
- and its jobs have been scheduled by Scheduler,
they will be picked by a Worker which will execute the build Bash script as generated by the build script compiler).
The worker goes through a series of stages while acquiring and preparing a VM, and running the build script. Each time the state of the job changes the worker will send a message that will be processed by Hub. These messages are:
job:receivesignals that the worker has picked up a job and is going to boot a VM for it. (This state is displayed as "booting" in the UI.)job:startsignals that the worker has started executing the build script.job:finishsignals that the worker has finished executing the build script.job:restartoccurs when the worker has troubles booting a VM, or looses connection to it while running the build script. (In this case the job's state will be reset to:createdso that Scheduler will queue it again, and Worker will try again.
Processing these messages Hub will change the job's state in the database,
set attributes such as received_at, potentially change the respective build's
state as well. It will then emit events such as job:started or
build:finished which will send out notifications to other parties (such as
the web UI via Pusher, GitHub commit status updates, email, IRC, webhook
notifications etc).
Travis Hub was the first service that we extracted from our Rails application apart from Travis Listener. It was huge, and did all the things that now are being split up into 6 applications (Gatekeeper, Scheduler, Hub, Logs, Sync, Tasks). Nowadays it is one of the smallest service that deals with our core models directly.
See the CONTRIBUTING.md file for information on how to contribute to travis-hub. Note that we're using a [central issue tracker] (https://github.com/travis-ci/travis-ci/issues) for all the Travis projects.
See MIT-LICENSE.