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diff --git a/README.md b/README.md new file mode 100644 index 000000000000..2b6c160d41bb --- /dev/null +++ b/README.md @@ -0,0 +1,49 @@ +# gerrit-queue + +This daemon automatically rebases and submits changesets from a Gerrit +instance, ensuring they still pass CI. + +In a usual gerrit setup with a linear master history, different developers +await CI feedback on a rebased changeset, then one clicks submit, and +effectively makes everybody else rebase again. `gerrit-queue` is meant to +remove these races to master. Developers can add a specific tag to a changeset, +and if all preconditions are met (passing CI and passing Code Review), +`gerrit-queue` takes care of rebasing and submitting it to master. + +## How it works +Gerrit only knows about Changesets (and some relations to other changesets), +but usually developers think in terms of multiple changesets. + +### The Fetching Phase +`gerrit-queue` fetches all changesets from gerrit, and tries to identify these +chains of changesets. We call them `Series`. All changesets need to have strict +parent/child relationships to be detected. + +Series are ordered by the number of changesets in them. This ensures longer +series are merged faster, and less rebases are triggered. In the future, this +might be extended to other metrics. + +### The Submit Phase +We loop over all series. If all changesets of a given series pass the required +preconditions (passing CI, passing Code Review, autosubmit Tag) and it's +rebased on top of the current destination branch's HEAD, it can be submitted. + +The current serie is removed from the list of series, and we update our HEAD to +the commit ID of the last commit in the submitted series. + +### The Rebase Phase +We loop over all remaining series. The first one matching the required +preconditions is rebased on top of the (advanced HEAD) (and if this fails, we +skip and keep trying with the next Series one after another). + + +These three phases are designed to be stateless, and currently triggered once +per run. +This is supposed to be moved to a more reactive model, so that the submit phase +is triggered by Webhooks for CI feedback, and we don't rebase too often + +## Compile and Run +```sh +go generate +GERRIT_PASSWORD=mypassword go run main.go --url https://gerrit.mydomain.com --username myuser --project myproject +``` |