[Feature flag] Rollout of `geo_treat_missing_files_as_sync_failed`
Summary
This issue is to rollout Geo: Treat missing files as sync failed on production,
that is currently behind the geo_treat_missing_files_as_sync_failed
feature flag.
This is a small but significant design change to files/blobs replicated by the Geo Self-Service Framework.
Before
When a file is missing on the primary, and a secondary attempts to sync it, the secondary considers it "synced", since its state matches the primary.
After
With this change, when the feature flag is enabled, the secondary considers the sync "failed", since it was unable to sync the file and this is an undesirable state.
Other implications
For blob types which have Geo verification enabled, this change short-circuits a logical loop in which sync succeeds but verification fails and then sync becomes failed and then sync gets retried.
This loop affects blobs replicated and verified by the Geo Self-Service Framework, including:
- Package Files
- Terraform State Versions
- Pipeline Artifacts
And soon to include:
- LFS Objects
- Pages Deployments
- Uploads
- CI Job Artifacts
This change is feature flagged behind
geo_treat_missing_files_as_sync_failed
so we can test in staging. Also
I intend to enable it by default before removing it. Therefore customers
will be able to easily switch back to old behavior for a whole
milestone, in case of any unforeseen problems with this design change.
Owners
- Team: groupgeo
- Most appropriate slack channel to reach out to:
#g_geo
- Best individual to reach out to: @mkozono
- PM: @nhxnguyen
Stakeholders
Expectations
What are we expecting to happen?
See description.
When is the feature viable?
N/A
What might happen if this goes wrong?
The feature flag can be turned off to revert to old behavior where "when a secondary attempts to sync a file but it turns out it's missing on the primary, the secondary will mark this as successfully synced". This should be safe.
What can we monitor to detect problems with this?
Consider mentioning checks for 5xx errors or other anomalies like an increase in redirects (302 HTTP response status)
-
<gitlab url>/admin/geo/nodes
e.g. on staging https://staging.gitlab.com/admin/geo/nodes -
Geo::EventWorker
jobs. Production GitLab.com doesn't use Geo and it seems like the dashboards don't have data from the staging Geo secondary site?
What can we check for monitoring production after rollouts?
Consider adding links to check for Sentry errors, Production logs for 5xx, 302s, etc.
Production GitLab.com does not use Geo. This change only affects GitLab deployments that are using Geo and have data being synced and have missing data on the primary.
Rollout Steps
Rollout on non-production environments
- Ensure that the feature MRs have been deployed to non-production environments.
-
/chatops run auto_deploy status <merge-commit-of-your-feature>
-
-
Enable the feature globally on non-production environments. -
/chatops run feature set geo_treat_missing_files_as_sync_failed true --dev
-
/chatops run feature set geo_treat_missing_files_as_sync_failed true --staging
-
-
Verify that the feature works as expected. Posting the QA result in this issue is preferable.
Specific rollout on production
N/A since there is no Geo secondary site in production.
- Ensure that the feature MRs have been deployed to both production and canary.
- [-]
/chatops run auto_deploy status <merge-commit-of-your-feature>
- [-]
- If you're using project-actor, you must enable the feature on these entries:
- [-]
/chatops run feature set --project=gitlab-org/gitlab geo_treat_missing_files_as_sync_failed true
- [-]
/chatops run feature set --project=gitlab-org/gitlab-foss geo_treat_missing_files_as_sync_failed true
- [-]
/chatops run feature set --project=gitlab-com/www-gitlab-com geo_treat_missing_files_as_sync_failed true
- [-]
- If you're using group-actor, you must enable the feature on these entries:
- [-]
/chatops run feature set --group=gitlab-org geo_treat_missing_files_as_sync_failed true
- [-]
/chatops run feature set --group=gitlab-com geo_treat_missing_files_as_sync_failed true
- [-]
- If you're using user-actor, you must enable the feature on these entries:
- [-]
/chatops run feature set --user=<your-username> geo_treat_missing_files_as_sync_failed true
- [-]
- [-] Verify that the feature works on the specific entries. Posting the QA result in this issue is preferable.
Preparation before global rollout
- [-] 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). => !77264 (merged) - [-] Announce on the feature issue an estimated time this will be enabled on GitLab.com.
- [-] Notify
#support_gitlab-com
and your team channel (more guidance when this is necessary in the dev docs).
Global rollout on production
N/A since there is no Geo secondary site in 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
).
- [-] Incrementally roll out the feature.
- If the feature flag in code has an actor, perform actor-based rollout.
- [-]
/chatops run feature set geo_treat_missing_files_as_sync_failed <rollout-percentage> --actors
- [-]
- If the feature flag in code does NOT have an actor, perform time-based rollout (random rollout).
- [-]
/chatops run feature set geo_treat_missing_files_as_sync_failed <rollout-percentage>
- [-]
- Enable the feature globally on production environment.
- [-]
/chatops run feature set geo_treat_missing_files_as_sync_failed true
- [-]
- If the feature flag in code has an actor, perform actor-based rollout.
- [-] Announce on the feature issue that the feature has been globally enabled.
- [-] Wait for at least one day for the verification term.
(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:
-
Create a merge request with the following changes. Ask for review and merge it. => !77274 (merged) -
Set the default_enabled
attribute in the feature flag definition totrue
. -
Create a changelog entry.
-
-
Ensure that the default-enabling MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post. - [-]
/chatops run auto_deploy status <merge-commit-of-default-enabling-mr>
- [-]
-
Close the feature issue to indicate the feature will be released in the current milestone. -
Set the next milestone to this rollout issue for scheduling the flag removal. - [-] (Optional) You can create a separate issue for scheduling the steps below to Release the feature.
- [-] Set the title to "[Feature flag] Cleanup
geo_treat_missing_files_as_sync_failed
". - [-] Execute the
/copy_metadata <this-rollout-issue-link>
quick action to copy the labels from this rollout issue. - [-] Link this rollout issue as a related issue.
- [-] Close this rollout issue.
- [-] Set the title to "[Feature flag] Cleanup
-
Close #208403 (closed) since it will be no longer relevant
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.
-
Create a merge request to remove geo_treat_missing_files_as_sync_failed
feature flag. => !78238 (merged)-
Remove all references to the feature flag from the codebase. -
Remove the YAML definitions for the feature from the repository. -
Create a changelog entry. -
Send !78238 (merged) for review and merge.
-
- [-] Ensure that the cleanup MR has been deployed to both production and canary.
If the merge request was deployed before the code cutoff,
the feature can be officially announced in a release blog post.
- [-]
/chatops run auto_deploy status <merge-commit-of-cleanup-mr>
- [-]
- [-] Close the feature issue to indicate the feature will be released in the current milestone.
-
Clean up the feature flag from all environments by running these chatops command in #production
channel:- [-]
/chatops run feature delete geo_treat_missing_files_as_sync_failed --dev
-
/chatops run feature delete geo_treat_missing_files_as_sync_failed --staging
- [-]
/chatops run feature delete geo_treat_missing_files_as_sync_failed
- [-]
-
Close this rollout issue.
Rollback Steps
-
This feature can be disabled by running the following Chatops command:
/chatops run feature set geo_treat_missing_files_as_sync_failed false