[Feature flag] Rollout of client Sentry feature flag (`enable_new_sentry_clientside_integration`)

Summary

This issue is to rollout using the new Sentry instance on production, that is currently behind the enable_new_sentry_clientside_integration feature flag.

Disabled feature flag: Use Sentry SDK v5 and report to the Sentry v9 DSN in the config (gitlab.yml)
Enabled feature flag: Use Sentry SDK v7 and report to the Sentry v22+ DSN in the settings (Admin UI values)

This is a user-actor feature flag, so we can do a progressive rollout for users.

Owners

Team: grouprunner
Most appropriate slack channel to reach out to: #wg_frontend-observability
Best individual to reach out to: @mrincon @mbobin
PM: N/A

Stakeholders

@samdbeckham
@timzallmann (Executive sponsor)

Expectations

What are we expecting to happen?

All events and error generated on the clientside switch over to the new Sentry instance.

What might happen if this goes wrong?

The feature flag can be disabled to switch users over to report in our old Sentry (https://sentry.gitlab.net/) instance.

What can we monitor to detect problems with this?

We should monitor errors reported at https://sentry.gitlab.net/ and at the new instance.

What can we check for monitoring production after rollouts?

All our client side errors should appear in the new Sentry instance.

Rollout Steps

Rollout on non-production environments

Ensure that the feature MRs have been deployed to non-production environments.
- !102790 (merged) /chatops run auto_deploy status <merge-commit-of-your-feature>
Enable the feature globally on non-production environments.
- /chatops run feature set enable_new_sentry_clientside_integration true --dev --staging --staging-ref
Verify that the feature works as expected. Posting the QA result in this issue is preferable. The best environment to validate the feature in is staging-canary as this is the first environment deployed to. Note you will need to make sure you are configured to use canary as outlined here when accessing the staging environment in order to make sure you are testing appropriately.

Specific rollout on production

Ensure that the feature MRs have been deployed to both production and canary.
- /chatops run auto_deploy status <merge-commit-of-your-feature>
Ensure the Sentry config (e.g. in gitabl.yml) is present for the old Sentry instance (v9).
Enable configure_sentry_in_application_settings to enable configuration of the settings:
- /chatops run feature set --user=mrincon enable_new_sentry_clientside_integration true
Visit /admin/application_settings/metrics_and_profiling to configure the Sentry settings for the new Sentry instance.
Enable Enable Sentry error tracking at Admin UI Sentry settings. (https://gitlab.com/admin/application_settings/metrics_and_profiling)
The gitlab application may have to restart in order for the settings to take place.
We are using user-actor, so we can enable the following to @mrincon can verify the settings are set up correctly:
- /chatops run feature set --user=mrincon enable_new_sentry_clientside_integration true
Verify that the feature works on the specific entries. Posting the QA result in this issue is preferable.
- @mrincon

Preparation before global rollout

Set a milestone to the rollout issue to signal for enabling and removing the feature flag when it is stable.
Check if the feature flag change needs to be accompanied with a change management issue. Cross link the issue here if it does.
Ensure that you or a representative in development can be available for at least 2 hours after feature flag updates in production. If a different developer will be covering, or an exception is needed, please inform the oncall SRE by using the @sre-oncall Slack alias.
Ensure that documentation has been updated (More info).
Leave a comment on the feature issue announcing estimated time when this feature flag will be enabled on GitLab.com.
Ensure that any breaking changes have been announced following the release post process to ensure GitLab customers are aware.
Notify #support_gitlab-com and your team channel (more guidance when this is necessary in the dev docs).

Global rollout on production

For visibility, all /chatops commands that target production should be executed in the #production slack channel and cross-posted (with the command results) to the responsible team's slack channel (#g_TEAM_NAME).

(Optional) Release the feature with the feature flag

If you're still unsure whether the feature is deemed stable but want to release it in the current milestone, you can change the default state of the feature flag to be enabled. To do so, follow these steps:

WARNING: This approach has the downside that it makes it difficult for us to clean up the flag. For example, on-premise users could disable the feature on their GitLab instance. But when you remove the flag at some point, they suddenly see the feature as enabled and they can't roll it back to the previous behavior. To avoid this potential breaking change, use this approach only for urgent matters.

Release the feature

After the feature has been deemed stable, the clean up should be done as soon as possible to permanently enable the feature and reduce complexity in the codebase.

You can either create a follow-up issue for Feature Flag Cleanup or use the checklist below in this same issue.

Rollback Steps

This feature can be disabled by running the following Chatops command:

/chatops run feature set enable_new_sentry_clientside_integration false

Edited Feb 17, 2023 by Marius Bobin