The Great Process Update of 2018

You may have noticed that our release cadence has slowed down significantly in the past few months. The bad news is we probably won’t get a release out this year (mainly due to end-of-year vacations and slowing down in general), but the good news is the next release is huge — big enough to bump us to v5.0 — and it’s just about ready. I’ll have more information on the next release in an upcoming post.

This post will go over all the changes we’ve made to our project structure and processes surrounding contribution. These changes aren’t very visible to end-users, but they set the stage for the community growth and collaboration that will make our future releases even better and bring more depth to our culture and ecosystem.

A newly minted process for RFCs

We’ve finally established a process for submitting and accepting RFCs! Head over to the concourse/rfcs repo if you want to check it out.

This new process enables anyone in the community to have a big impact on Concourse’s direction. I’m really looking forward to seeing where this goes. We’ll be posting status updates for RFCs on this blog to notify the community of RFCs that are newly opened or near acceptance.

We've already started submitting RFCs for substantial features like Resources V2 and RBAC, though we jumped the gun a bit on implementation as we hadn’t yet figured out what we wanted from the RFC process (we just needed a better way to plan things in the open). There are a few loose ends to tidy up with existing RFCs now that we have a full process in place.

Credit where it’s due: this process based pretty heavily on Rust’s. Just about every detail seemed to apply just as appropriately to Concourse, and we’re just as cautious about far-reaching changes, so it was a great match.

Switching from CLA to DCO

Up until now, all pull request authors have had to sign off on the Pivotal CLA in order for their pull request to be accepted (unless it was an “obvious fix”).

On occasion contributors would get caught in a corporate quagmire when trying to get their company to sign off on the CLA, and it was also kind of jarring for individuals. The need for something like the CLA hasn’t gone away, but we felt it may have been hindering more than helping.

So, we’re abandoning the CLA process and instead adopting the Developer Certificate of Origin (“DCO”) process. This process is much more lightweight, only requiring pull request authors to include a “Signed-off-by:” line in each commit, which can be done via git commit -s. More information on this is available in CONTRIBUTING.md.

Completing the Great Project Restructuring of 2018

The single biggest cause of the release slowdown has been The Great Project Restructuring of 2018, which was a massive revamp of how we develop, build, test, and ship Concourse. We knew this would be a “stop-the-world” transition that would prevent us from shipping for a while, but we really had to bite the bullet at some point.

The focal point of this restructuring: almost all of Concourse’s code now lives in one big concoursemonorepo, using the new Go 1.11 module system to track dependencies. We’ve replaced our BOSH-centric development and pipeline workflow with a Docker-based workflow which is more intuitive and has a much faster feedback cycle.

This means you can now git clone the Concourse repo and get a cluster built from source and running in single command: docker-compose up. It’s never been easier to make changes and test them out locally. Check out the new CONTRIBUTING.md for more information!

This change kicked off a ripple effect that improved a ton of things about the developer, contributor, and operator experience:

Now that all the code is together in one repo, cross-cutting changes can now be submitted as a single pull request! 🎊 Pull requests now trigger acceptance tests too, which is something we couldn’t really do easily before.
Resources are now versioned and shipped independently of Concourse versions. Each resource is published as concourse/<name>-resource with appropriate tags (e.g. 1.2.3, 1.2, 1, latest, dev). This means you can refer to specific versions when necessary by using resource_types: in your pipeline. A core set of resource types will still be shipped with Concourse, at whichever version they were when the release was frozen.
The concourse repo is no longer a BOSH release; we’ve split it out into its own repository instead. The new BOSH release simply wraps the binary distribution, rather than building from source. This reduces the surface area for support and removes any discrepancies between the platforms — everything just uses the binary now! This also makes deploying the BOSH release faster because there’s not much to compile.
We’ve changed how the concourse executable is packaged. We’re switching to a .tgz format containing the binary and its dependencies, rather than a self-extracting “all-in-one” binary. This results in way fewer moving parts and dramatically reduces concourse worker start-up time.

Where are we now?

Overall, I think these recent changes may be the most important thing we’ve done for the project since its inception, even if it meant not shipping for a while.

The RFC process will make it easier to collaborate, switching to the DCO removes a hurdle for new contributors, and the the new project structure should dramatically improve the developer experience.

I’d like to give special thanks to everyone that has tried out and given feedback on this new development process, and all the users that have waited patiently for the next release. 😅

What’s next?

Well, now that the dust is settling it’s time to actually start shipping software again. The next post will go over what’s in store for 5.0 and peek ahead into what we’re planning for 2019. See you then!