# Feature flag controls ## Access To be able to turn on/off features behind feature flags in any of the GitLab Inc. provided environments such as staging and production, you need to have access to the [Chatops](../chatops_on_gitlabcom.md) bot. The Chatops bot is currently running on the ops instance, which is different from or . Follow the Chatops document to [request access](../chatops_on_gitlabcom.md#requesting-access). Once you are added to the project test if your access propagated, run: ```shell /chatops run feature --help ``` ## Rolling out changes When the changes are deployed to the environments it is time to start rolling out the feature to our users. The exact procedure of rolling out a change is unspecified, as this can vary from change to change. However, in general we recommend rolling out changes incrementally, instead of enabling them for everybody right away. We also recommend you to _not_ enable a feature _before_ the code is being deployed. This allows you to separate rolling out a feature from a deploy, making it easier to measure the impact of both separately. GitLab's feature library (using [Flipper](https://github.com/jnunemaker/flipper), and covered in the [Feature Flags process](process.md) guide) supports rolling out changes to a percentage of time to users. This in turn can be controlled using [GitLab Chatops](../../ci/chatops/README.md). For an up to date list of feature flag commands please see [the source code](https://gitlab.com/gitlab-com/chatops/blob/master/lib/chatops/commands/feature.rb). Note that all the examples in that file must be preceded by `/chatops run`. If you get an error "Whoops! This action is not allowed. This incident will be reported." that means your Slack account is not allowed to change feature flags or you do not [have access](#access). ### Enabling a feature for preproduction testing As a first step in a feature rollout, you should enable the feature on and . These two environments have different scopes. `dev.gitlab.org` is a production CE environment that has internal GitLab Inc. traffic and is used for some development and other related work. `staging.gitlab.com` has a smaller subset of GitLab.com database and repositories and does not have regular traffic. Staging is an EE instance and can give you a (very) rough estimate of how your feature will look/behave on GitLab.com. Both of these instances are connected to Sentry so make sure you check the projects there for any exceptions while testing your feature after enabling the feature flag. For these preproduction environments, the commands should be run in a Slack channel for the stage the feature is relevant to. For example, use the `#s_monitor` channel for features developed by the Monitor stage, Health group. To enable a feature for 25% of all users, run the following in Slack: ```shell /chatops run feature set new_navigation_bar 25 --dev /chatops run feature set new_navigation_bar 25 --staging ``` ### Enabling a feature for GitLab.com When a feature has successfully been [enabled on a preproduction](#enabling-a-feature-for-preproduction-testing) environment and verified as safe and working, you can roll out the change to GitLab.com (production). #### Communicate the change Some feature flag changes on GitLab.com should be communicated with parts of the company. The developer responsible needs to determine whether this is necessary and the appropriate level of communication. This depends on the feature and what sort of impact it might have. As a guideline: - For simple features that are low-risk, and easily rolled back, then just proceed to [enabling the feature in `#production`](#process). - For features that will impact user experience consider notifying `#support_gitlab-com` beforehand. - For features with significant downstream effects (e.g.: turning on/off Elasticsearch indexing) consider coordinating with `#production` beforehand. #### Process Before toggling any feature flag, check that there are no ongoing significant incidents on GitLab.com. You can do this by checking the `#production` and `#incident-management` Slack channels, or looking for [open incident issues](https://gitlab.com/gitlab-com/gl-infra/production/issues/?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=incident) (although check the dates and times). We do not want to introduce changes during an incident, as it can make diagnosis and resolution of the incident much harder to achieve, and also will largely invalidate your rollout process as you will be unable to assess whether the rollout was without problems or not. If there is any doubt, ask in `#production`. The following `/chatops` commands should be performed in the Slack `#production` channel. When you begin to enable the feature, please link to the relevant Feature Flag Rollout Issue within a Slack thread of the first `/chatops` command you make so people can understand the change if they need to. To enable a feature for 25% of all users, run the following in Slack: ```shell /chatops run feature set new_navigation_bar 25 ``` This will enable the feature for GitLab.com, with `new_navigation_bar` being the name of the feature. This command does *not* enable the feature for 25% of the total users. Instead, when the feature is checked with `enabled?`, it will return `true` 25% of the time. If you are not certain what percentages to use, simply use the following steps: 1. 25% 1. 50% 1. 75% 1. 100% Between every step you'll want to wait a little while and monitor the appropriate graphs on . The exact time to wait may differ. For some features a few minutes is enough, while for others you may want to wait several hours or even days. This is entirely up to you, just make sure it is clearly communicated to your team, and the Production team if you anticipate any potential problems. Feature gates can also be actor based, for example a feature could first be enabled for only the `gitlab` project. The project is passed by supplying a `--project` flag: ```shell /chatops run feature set --project=gitlab-org/gitlab some_feature true ``` For groups the `--group` flag is available: ```shell /chatops run feature set --group=gitlab-org some_feature true ``` Note that actor-based gates are applied before percentages. For example, considering the `group/project` as `gitlab-org/gitlab` and a given example feature as `some_feature`, if you run these 2 commands: ```shell /chatops run feature set --project=gitlab-org/gitlab some_feature true /chatops run feature set some_feature 25 ``` Then `some_feature` will be enabled for both 25% of users and all users interacting with `gitlab-org/gitlab`. NOTE: **Note:** **Percentage of time** rollout is not a good idea if what you want is to make sure a feature is always on or off to the users. ### Feature flag change logging Any feature flag change that affects GitLab.com (production) will automatically be logged in an issue. The issue is created in the [gl-infra/feature-flag-log](https://gitlab.com/gitlab-com/gl-infra/feature-flag-log/issues?scope=all&utf8=%E2%9C%93&state=closed) project, and it will at minimum log the Slack handle of person enabling a feature flag, the time, and the name of the flag being changed. The issue is then also posted to GitLab's internal [Grafana dashboard](https://dashboards.gitlab.net/) as an annotation marker to make the change even more visible. Changes to the issue format can be submitted in the [Chatops project](https://gitlab.com/gitlab-com/chatops). ## Cleaning up Once the change is deemed stable, submit a new merge request to remove the feature flag. This ensures the change is available to all users and self-managed instances. Make sure to add the ~"feature flag" label to this merge request so release managers are aware the changes are hidden behind a feature flag. If the merge request has to be picked into a stable branch, make sure to also add the appropriate `~"Pick into X.Y"` label (e.g. `~"Pick into 13.0"`). See [the process document](process.md#including-a-feature-behind-feature-flag-in-the-final-release) for further details. When a feature gate has been removed from the code base, the feature record still exists in the database that the flag was deployed too. The record can be deleted once the MR is deployed to each environment: ```shell /chatops run feature delete some_feature --dev /chatops run feature delete some_feature --staging ``` Then, you can delete it from production after the MR is deployed to prod: ```shell /chatops run feature delete some_feature ```