1.. _docs-rollers: 2 3======= 4Rollers 5======= 6 7----------------- 8What is a roller? 9----------------- 10A roller is an infra job that updates the revision of a pinned project (or 11version of a pinned CIPD package) in a repository with submodules or an 12Android Repo Tool manifest. The Pigweed Infra team generally maintains the 13logic and configuration of rollers, while various project and/or package 14owners across are responsible for keeping them green. 15 16----------- 17Our rollers 18----------- 19Rollers from Pigweed into downstream projects can be seen on the 20`Pigweed Console <https://ci.chromium.org/p/pigweed/g/pigweed.pigweed/console>`_. 21Many more rollers are visible when logged in using an @google.com account than 22when not. 23 24Rollers specific to individual downstream projects can be found by browsing 25the :ref:`builder visualization <docs-builder-viz>` and looking under the 26"roll" columns. 27 28-------------------- 29How do rollers work? 30-------------------- 31Project rollers will poll Gitiles periodically (often every three hours, but 32this is configurable) for new commits to watched 33repositories. Package rollers will poll CIPD at their configured frequencies 34for new packages which match their watched refs (e.g. 'latest'). 35 36When a new change is detected, luci-scheduler emits a 'trigger' for the 37roller. The 'trigger' does not necessarily invoke the roller immediately as 38luci-scheduler is configured to only allow a single job of each roller to be 39running at once. It will batch triggers until there is no job running, then 40create a roller job with the properties of the latest trigger in the batch. 41 42Once the roller job begins, it creates a change which updates the relevant 43project or package pin(s) and attempts to submit the change via CQ. If the CQ 44run fails, then the roller will abandon that change. If the CQ run succeeds, the 45change is submitted and the roller succeeds. 46 47On most hosts, rollers vote on the ``Bot-Commit`` label which bypasses the 48``Code-Review`` requirement. On other hosts, rollers vote on ``Code-Review``, 49or Gerrit is configured to not enforce the ``Code-Review`` requirement for 50changes uploaded by the roller. 51 52In the event of a CQ failure, if the roller attempts to re-roll the exact same 53revision or package(s), it will re-use the existing change and only re-run the 54failing portions of CQ. 55 56------------------------------- 57How do I fix a roller breakage? 58------------------------------- 59Most rollers will fix themselves. Failing rollers are periodically rerun by 60the 61`"rerunner" builders <https://ci.chromium.org/ui/p/pigweed/g/rerunner/builders>`_, 62so any flaky tests or temporary failures should resolve themselves. 63 64However, if you are a Googler on a team using Pigweed's infrastructure, you 65should be able to manually trigger a roller by finding it in the Builder Viz 66and clicking the "scheduler" link. (You may need to log in to 67luci-scheduler.) This is batched with all other 'triggers' as to not disrupt 68the normal roller flow, but will allow you to restart the roll process. 69 70----------------------------------------------- 71How do I disable a roller? Create a new roller? 72----------------------------------------------- 73*(Googlers only)* See `go/pw-config-tasks <http://go/pw-config-tasks>`_. But most 74of the time the appropriate action is to file a bug at 75`go/pw-infra-bug <http://go/pw-infra-bug>`_. 76