Squashing Pull requests and preserving signatures

[smuzaffar]

Hi @cms-sw/all-l2 , On Monday 5th Feb, we are going to merge https://github.com/cms-sw/cms-bot/pull/2144 which allows cms-bot to recognize squashed pull requests without resetting the L2's signatures. This change allow us to

• Not reset L2's signatures as long as the changes proposed by a force update are identical to changes before the force push. This includes

  • squashing multiple commits (c1, c2, c3, ..., cn) in to one (or more) new commit(s) (cx)
  • force pushing a different set of commits which have overall identical changes

• Reset L2's signatures if commit(s) dated earlier than the L2's signature are added to PR. This could happen when a user created two sets of changes e.g. branch B1 with commits c1,c2 and branch B2 with commits c1, c2, c3 and then opened a PR using branch B1 which is then signed Sn by L2 and then user pushed B2 to B1. Currently bot does not reset the signatures as timestamp of commits c3 is earlier than Sn but with cms-sw/cms-bot#2144 bot should be able to catch such changes and properly reset signatures.

• Warn user about large number of commits in a PR. As Github API only allows us to process max of 250 commits, so in order to avoid missing any changes

  • bot will issue a soft warning if PR's commit count is over 150 and will not process such PRs. If a L2 thinks that it is worth to have over 150 commits in PR then he/she can add +commit-count comment to override this.
  • bot will issue a hard warning if PR's commit count is over 240 and will not process such PRs unless some of the commits are squashed.

Note that squashing PR commits creates a new commit so the Pull request's status checks will be reset. But bot will automatically re-run code-checks and PR tests (if any L2 has already signed the changes before the squash).

Please let us know if you have any questions/concerns/suggestions

Squashing CMSSW PRs was discussed in detail here

[cmsbuild]

cms-bot internal usage

[cmsbuild]

A new Issue was created by @smuzaffar Malik Shahzad Muzaffar.

@smuzaffar, @sextonkennedy, @makortel, @rappoccio, @Dr15Jones, @antoniovilela can you please review it and eventually sign/assign? Thanks.

cms-bot commands are listed here

[makortel]

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