<!-- Title suggestion: [Feature flag] Enable description of feature --> ## What Remove the `:use_marker_ranges` feature flag ... ## Owners - Team: ~"group::source code" - Most appropriate slack channel to reach out to: `#g_create_source-code-be` - Best individual to reach out to: @vyaklushin <!-- Title suggestion: [Feature flag] Enable description of feature --> ## Stakeholders <!-- Are there any other stages or teams involved that need to be kept in the loop? - Name of a PM - The Support Team - The Delivery Team --> ## The Rollout Plan <!-- Describe how the feature should be rolled out, and check the right boxes. You can check multiple if applicable --> - [X] Partial Rollout on GitLab.com with beta groups - [ ] Rollout on GitLab.com for a certain period (How long) - [X] Percentage Rollout on GitLab.com - XX% If it is possible to perform an incremental rollout, this should be preferred. Proposed increments are: `10%`, `50%`, `100%`. Proposed minimum time between increments is 15 minutes. - [ ] Rollout Feature for everyone as soon as it's ready <!-- Which dashboards from https://dashboards.gitlab.net are most relevant? Sentry errors reports can also be useful to review --> **Beta Groups/Projects:** <!-- If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example. --> - `gitlab-org/gitlab` project - `gitlab-org`/`gitlab-com` groups - ... ## Expectations ### What are we expecting to happen? There should be no visible impact on merge request diff rendering. When FF is enabled we pre-populate `Diff::Line` objects with information about changed characters in the diff string and rely on this information for rendering. Currently, we calculate the diff ranges on demand and don't store them in the object. <!-- Describe the expected outcome when rolling out this feature --> ### What might happen if this goes wrong? Merge request diff rendering can work incorrectly. <!-- Should the feature flag be turned off? Any MRs that need to be rolled back? Communication that needs to happen? What are some things you can think of that could go wrong - data loss or broken pages? --> ### What can we monitor to detect problems with this? <!-- Which dashboards from https://dashboards.gitlab.net are most relevant? --> ## Rollout Timeline <!-- Please check which steps are needed and remove those which don't apply --> **Initial Rollout** *Preparation Phase* - [x] Enable on staging (`/chatops run feature set use_marker_ranges true --staging`) - [x] Test on staging - [ ] Ensure that documentation has been updated ([More info](https://docs.gitlab.com/ee/development/documentation/feature_flags.html#features-that-became-enabled-by-default)) - [ ] Announce on the issue an estimated time this will be enabled on GitLab.com *Partial Rollout Phase* - [x] Enable on GitLab.com for individual groups/projects listed above and verify behaviour (`/chatops run feature set --project=gitlab-org/gitlab use_marker_ranges true`) - [x] Verify behaviour (See Beta Groups) and add details with screenshots as a comment on this issue **Global Availability** ([More Info](https://docs.gitlab.com/ee/development/feature_flags/controls.html#communicate-the-change)) *(Please Note that Beta,Alpha and General Availability (GA) are handled on a product level and not the feature-flag)* <!-- The next checkboxes are probably only needed for high visibility and/or critical rollouts. Please refer to the official documentation linked above for more clarification --> - [ ] Coordinate a time to enable the flag with `#production` and `#g_delivery` on slack. - [ ] Announce on the issue an estimated time this will be enabled on GitLab.com - [ ] Make the feature flag enabled by default i.e. Change `default_enabled` to `true` - [ ] Enable on GitLab.com by running chatops command in `#production` (`/chatops run feature set use_marker_ranges true`) - [ ] Announce on the issue that the flag has been enabled - [ ] Cross post chatops slack command to `#support_gitlab-com` ([more guidance when this is necessary in the dev docs](https://docs.gitlab.com/ee/development/feature_flags/controls.html#where-to-run-commands)) and in your team channel **Cleanup** This is an __important__ phase, that should be either done in the next Milestone or as soon as possible. For the cleanup phase, please follow our documentation on how to [clean up the feature flag](https://docs.gitlab.com/ee/development/feature_flags/controls.html#cleaning-up). <!-- The checklist here is to keep track of it's status for stakeholders --> - [ ] Announce on the issue that the flag has been enabled - [ ] Remove `:feature_name` feature flag - [ ] Remove all references to the feature flag from the codebase - [ ] Remove the YAML definitions for the feature from the repository - [ ] Create a Changelog Entry - [ ] Clean up the feature flag from all environments by running this chatops command in `#production` channel `/chatops run feature delete use_marker_ranges`. **Final Step** - [ ] Close this rollout issue for the feature flag after the feature flag is removed from the codebase. ## Rollback Steps - [ ] This feature can be disabled by running the following Chatops command: ``` /chatops run feature set --project=gitlab-org/gitlab use_marker_ranges false ```