Avoiding required stops
Required stops are any changes to GitLab components or
dependencies that result in the need to upgrade to and stop at a specific
major.minor
version when upgrading GitLab.
While Development maintains a maintenance policy that results in a three-release (3 month) backport window - GitLab maintains a much longer window of version support that includes the current major version, as well as the two previous major versions. Based on the schedule of previous major releases, GitLab customers can lag behind the current release for up to three years and still expect to have support for upgrades.
For example, a GitLab user upgrading from GitLab 14.0.12 to GitLab 16.1,
which is a fully supported upgrade path, may have
the following required stops: 14.3.6
, 14.9.5
, 14.10.5
, 15.0.5
, 15.1.6
,
15.4.6
, and 15.11.11
before upgrading to the latest 16.1.z
version.
Past required stops have not been discovered for months after their introduction, often as the result of extensive troubleshooting and assistance from Support Engineers, Customer Success Managers, and Development Engineers as users upgrade across greater than 1-3 minor releases.
Wherever possible, a required stop should be avoided. If it can’t be avoided, the required stop should be aligned to a scheduled required stop.
In cases where we are considering retroactively declaring an unplanned required stop, please contact the Distribution team product manager to advise on next steps. If there is uncertainty about whether we should declare a required stop, the Distribution product manager may escalate to GitLab product leadership (VP or Chief Product Officer) to make a final determination. This may happen, for example, if a change might require a stop for a small subset of very large self-managed installations and there are well-defined workarounds if customers run into issues.
Scheduled required stops are often implemented for the previous major
.minor
release just prior to a major
version release in order to accommodate multiple
planned deprecations and known
breaking changes.
Additionally, as of GitLab 16, we have introduced
scheduled major
.minor
required stops:
During GitLab 16.x, we are scheduling two or three required upgrade stops.
We will give at least two milestones of notice when we schedule a required upgrade stop. The first planned required upgrade stop is scheduled for GitLab 16.3. If nothing is introduced requiring an upgrade stop, GitLab 16.3 will be treated as a regular upgrade.
Causes of required stops
Inaccurate assumptions about completed migrations
The majority of required stops are due to assumptions about the state of the data model in a given release, usually in the form of interdependent database migrations, or code changes that assume that schema changes introduced in prior migrations have completed by the time the code loads.
Designing changes and migrations for backwards compatibility between versions can mitigate stop concerns with continuous or “zero-downtime” upgrades. However, the contract phase will likely introduce a required stop when a migration/code change is introduced that requires that background migrations have completed before running or loading.
Examples
- GitLab
12.1
: Introduced a background migration changingmerge_status
in MergeRequests depending on thestate
value. Thestate
attribute was removed in12.10
. It took until13.6
to document the required stop. - GitLab
13.8
: Includes a background migration to deal with duplicate service records. In13.9
, a unique index was applied in another migration that depended on the background migration completing. Not discovered/documented until GitLab14.3
- GitLab
14.3
: Includes a potentially long-running background migration againstmerge_request_diff_commits
that was foregrounded in14.5
. This change resulted in extensive downtime for users with large GitLab installations. Not documented until GitLab15.1
- GitLab
14.9
: Includes a batched background migration fornamespaces
andprojects
that needs to finish before another batched background migration added in14.10
executes, forcing a required stop. The migration can take hours or days to complete on large GitLab installations.
Additional details as well as links to related issues and merge requests can be found in: Issue: Put in place measures to avoid addition/proliferation of GitLab upgrade path stops
Removal of code workarounds and mitigations
Similar to assumptions about the data model/schema/migration state, required
major.minor
stops have been introduced due to the intentional removal of
code implemented to workaround previously discovered issues.
Examples
- GitLab
13.1
: A security fix in Rails6.0.3.1
introduced a CSRF token change (causing a canary environment incident). We introduced code to maintain acceptance of previously generated tokens, and removed the code in13.2
, creating a known required stop in13.1
. - GitLab
15.4
: Introduces a migration to fix an inaccurateexpires_at
timestamp for job artifacts that had been mitigated in code since GitLab14.9
. The workaround was removed in GitLab15.6
, causing15.4
to be a required stop.
Deprecations
Deprecations, particularly breaking changes can also cause required stops if they introduce long migration delays or require manual actions on the part of GitLab administrators.
These are generally accepted as a required stop around a major release, either
stopping at the latest major.minor
release immediately proceeding
a new major
release, and potentially the latest major.0
patch release, and
to date, discovered required stops related to deprecations have been limited to
these releases.
Examples
Examples of deprecations are too numerous to be listed here, but can found in the deprecations and removals by version as well as the version-specific upgrading instructions, version-specific changes for the GitLab package (Omnibus), and GitLab chart upgrade notes.
Further reading
- Documentation: Database - Adding required stops
- Documentation: Upgrading GitLab
- Issue: Put in place measures to avoid addition/proliferation of GitLab upgrade path stops
- Issue: Brainstorm ways for background migrations to be finalized without introducing a required upgrade step
- Issue: Scheduled required paths for GitLab upgrades to improve UX
- Epic: GitLab Releases and Maintenance policies