2024-07-30: Reduce git & JWT auth rate limit

Production Change

Change Summary

This change reduces the rate limit targeting failed requests for git operations and the /jwt/auth endpoint. This rate limit was raised on 2024-05-14 as a response to reduce the impact of expired tokens causing IP addresses to be blocked.

We are now reducing this rate limit in line with our plan to iterate on a new longer term setting for this rate limit.

There is an hour long period of monitoring defined in the steps to ensure that we're also catching hourly traffic that could cause issues for customers.

Change Details

1. Services Impacted - Git operations, GitLab API, GitLab registry auth
2. Change Technician - @jcstephenson
3. Change Reviewer - @marin
4. Time tracking - 80 minutes
5. Downtime Component - none

Set Maintenance Mode in GitLab

If your change involves scheduled maintenance, add a step to set and unset maintenance mode per our runbooks. This will make sure SLA calculations adjust for the maintenance period.

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 80

• Run pre-flight checks
  • Run analysis of the potentially impacted users based on this process (internal link)
• Set label changein-progress /label ~change::in-progress
• Post in internal Slack channels for visibility and transparency of the change.
• Merge MR to reduce the rate limit.
• Observe the deployment pipeline for gprd deployments
• Wait for approximately 1 hour to allow traffic any traffic which may be affected to start hitting the rate limits.
• Merge MR to update documentation with the new rate limit.
• Set label changecomplete /label ~change::complete

Rollback

Rollback steps - steps to be taken in the event of a need to rollback this change

Estimated Time to Complete (mins) - 30

• Revert MR to reduce the rate limit.
• Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

• Metric: Rates of 4xx responses
  • Location: Grafana explore
  • What changes to this metric should prompt a rollback: A sudden increase in 429 responses.
• Metric: Rack attack rate limit events
  • Location: Kibana
  • What changes to this metric should prompt a rollback: A sudden increase in rate limit events requests.

Change Reviewer checklist

C4 C3 C2 C1:

• Check if the following applies:
  • The scheduled day and time of execution of the change is appropriate.
  • The change plan is technically accurate.
  • The change plan includes estimated timing values based on previous testing.
  • The change plan includes a viable rollback plan.
  • The specified metrics/monitoring dashboards provide sufficient visibility for the change.

C2 C1:

• Check if the following applies:
  • The complexity of the plan is appropriate for the corresponding risk of the change. (i.e. the plan contains clear details).
  • The change plan includes success measures for all steps/milestones during the execution.
  • The change adequately minimizes risk within the environment/service.
  • The performance implications of executing the change are well-understood and documented.
  • The specified metrics/monitoring dashboards provide sufficient visibility for the change.
    • If not, is it possible (or necessary) to make changes to observability platforms for added visibility?
  • The change has a primary and secondary SRE with knowledge of the details available during the change window.
  • The change window has been agreed with Release Managers in advance of the change. If the change is planned for APAC hours, this issue has an agreed pre-change approval.
  • The labels blocks deployments and/or blocks feature-flags are applied as necessary.

Change Technician checklist

• Check if all items below are complete:
  • The change plan is technically accurate.
  • This Change Issue is linked to the appropriate Issue and/or Epic
  • Change has been tested in staging and results noted in a comment on this issue.
  • A dry-run has been conducted and results noted in a comment on this issue.
  • The change execution window respects the Production Change Lock periods.
  • For C1 and C2 change issues, the change event is added to the GitLab Production calendar.
  • For C1 and C2 change issues, the SRE on-call has been informed prior to change being rolled out. (In #production channel, mention @sre-oncall and this issue and await their acknowledgement.)
  • For C1 and C2 change issues, the SRE on-call provided approval with the eoc_approved label on the issue.
  • For C1 and C2 change issues, the Infrastructure Manager provided approval with the manager_approved label on the issue.
  • Release managers have been informed prior to any C1, C2, or blocks deployments change being rolled out. (In #production channel, mention @release-managers and this issue and await their acknowledgment.)
  • There are currently no active incidents that are severity1 or severity2
  • If the change involves doing maintenance on a database host, an appropriate silence targeting the host(s) should be added for the duration of the change.