ci-all-nix-prs: Draft

rfcs/0000-ci-all-nix-prs.md

@@ -1,7 +1,7 @@
 ---
-feature: (fill me in with a unique ident, my_awesome_feature)
-start-date: (fill me in with today's date, YYYY-MM-DD)
-author: (name of the main author)
+feature: ci-all-nix-prs
+start-date: 2019-10-30
+author: John Ericson (@Ericson2314)
 co-authors: (find a buddy later to help our with the RFC)
 shepherd-team: (names, to be nominated and accepted by RFC steering committee)
 shepherd-leader: (name to be appointed by RFC steering committee)
@@ -11,39 +11,50 @@ related-issues: (will contain links to implementation PRs)
 # Summary
 [summary]: #summary
 
-One paragraph explanation of the feature.
+Build all Nix PRs in CI.
+Do not merge any PR until it passes CI.
 
 # Motivation
 [motivation]: #motivation
 
-Why are we doing this? What use cases does it support? What is the expected
-outcome?
+There is a (famous blog post)[blog-post] that everyone is sloppy and doing CI wrong.
+This isn't just bad for releasing software smoothly, but also increases the burden for new contributors because it is harder to judge the correctness of PRs at a glance (is it broken? Did I break it?).
+I personally find it harder to contribute, I have to worry about double checking all my work on platforms I don't have as-easy access to, like Darwin.
+
+We cannot yet do this for all of Nixpkgs, sadly, due to resource limits.
+But, there is no reason we cannot do it for Nix itself.
 
 # Detailed design
 [design]: #detailed-design
 
-This is the bulk of the RFC. Explain the design in enough detail for somebody
-familiar with the ecosystem to understand, and implement.  This should get
-into specifics and corner-cases, and include examples of how the feature is
-used.
+Set up Hydra declarative jobsets to build all Nix PRs.
+Those with merge access should be instructed not to merge a PR until CI passes.
+Merge master into PRs or rebase before merge as a crude stop-gap to avoid master becoming an untested tree due to a merge commit.
+
+If Hydra gains the ability to keep master always working obviating the manual steps above beyond the PR jobs, use that ability.
+
+If a new CI is used, ensure that is also keeps master in an always-building state.
 
 # Drawbacks
 [drawbacks]: #drawbacks
 
-Why should we *not* do this?
+More process to follow.
 
 # Alternatives
 [alternatives]: #alternatives
 
-What other designs have been considered? What is the impact of not doing this?
+Merely build all PRs, and maintainers are still allowed to merge broken ones / not take care to avoid untested merge commits.
 
 # Unresolved questions
 [unresolved]: #unresolved-questions
 
-What parts of the design are still TBD or unknowns?
+Nothing.
 
 # Future work
 [future]: #future-work
 
-What future work, if any, would be implied or impacted by this feature
-without being directly part of the work?
+- Remove the manual parts of this process.
+
+- Also apply to other smaller official repos, like `cabal2nix`.
+
+[blog-post]: https://graydon2.dreamwidth.org/1597.html