Geo data types support

A Geo data type is a specific class of data that is required by one or more GitLab features to store relevant information.

To replicate data produced by these features with Geo, we use several strategies to access, transfer, and verify them.

Data types

We currently distinguish between three different data types:

See the list below of each feature or component we replicate, its corresponding data type, replication, and verification methods:

Type Feature / component Replication method Verification method
Database Application data in PostgreSQL Native Native
Database Redis N/A (1) N/A
Database Elasticsearch Native Native
Database Personal snippets PostgreSQL Replication PostgreSQL Replication
Database Project snippets PostgreSQL Replication PostgreSQL Replication
Database SSH public keys PostgreSQL Replication PostgreSQL Replication
Git Project repository Geo with Gitaly Gitaly Checksum
Git Project wiki repository Geo with Gitaly Gitaly Checksum
Git Project designs repository Geo with Gitaly Gitaly Checksum
Git Object pools for forked project deduplication Geo with Gitaly Not implemented
Blobs User uploads (filesystem) Geo with API Not implemented
Blobs User uploads (object storage) Geo with API/Managed (2) Not implemented
Blobs LFS objects (filesystem) Geo with API Not implemented
Blobs LFS objects (object storage) Geo with API/Managed (2) Not implemented
Blobs CI job artifacts (filesystem) Geo with API Not implemented
Blobs CI job artifacts (object storage) Geo with API/Managed (2) Not implemented
Blobs Archived CI build traces (filesystem) Geo with API Not implemented
Blobs Archived CI build traces (object storage) Geo with API/Managed (2) Not implemented
Blobs Container registry (filesystem) Geo with API/Docker API Not implemented
Blobs Container registry (object storage) Geo with API/Managed/Docker API (2) Not implemented
Blobs Package registry (filesystem) Geo with API Not implemented
Blobs Package registry (object storage) Geo with API/Managed (2) Not implemented
Blobs Versioned Terraform State (filesystem) Geo with API Not implemented
Blobs Versioned Terraform State (object storage) Geo with API/Managed (2) Not implemented
Blobs External Merge Request Diffs (filesystem) Geo with API Not implemented
Blobs External Merge Request Diffs (object storage) Geo with API/Managed (2) Not implemented
  • (1): Redis replication can be used as part of HA with Redis sentinel. It’s not used between Geo nodes.
  • (2): Object storage replication can be performed by Geo or by your object storage provider/appliance native replication feature.

Git repositories

A GitLab instance can have one or more repository shards. Each shard has a Gitaly instance that is responsible for allowing access and operations on the locally stored Git repositories. It can run on a machine with a single disk, multiple disks mounted as a single mount-point (like with a RAID array), or using LVM.

It requires no special filesystem and can work with NFS or a mounted Storage Appliance (there may be performance limitations when using a remote filesystem).

Communication is done via Gitaly’s own gRPC API. There are three possible ways of synchronization:

  • Using regular Git clone/fetch from one Geo node to another (with special authentication).
  • Using repository snapshots (for when the first method fails or repository is corrupt).
  • Manual trigger from the Admin UI (a combination of both of the above).

Each project can have at most 3 different repositories:

  • A project repository, where the source code is stored.
  • A wiki repository, where the wiki content is stored.
  • A design repository, where design artifacts are indexed (assets are actually in LFS).

They all live in the same shard and share the same base name with a -wiki and -design suffix for Wiki and Design Repository cases.

Blobs

GitLab stores files and blobs such as Issue attachments or LFS objects into either:

  • The filesystem in a specific location.
  • An Object Storage solution. Object Storage solutions can be:
    • Cloud based like Amazon S3 Google Cloud Storage.
    • Hosted by you (like MinIO).
    • A Storage Appliance that exposes an Object Storage-compatible API.

When using the filesystem store instead of Object Storage, you need to use network mounted filesystems to run GitLab when using more than one server.

With respect to replication and verification:

  • We transfer files and blobs using an internal API request.
  • With Object Storage, you can either:
    • Use a cloud provider replication functionality.
    • Have GitLab replicate it for you.

Database

GitLab relies on data stored in multiple databases, for different use-cases. PostgreSQL is the single point of truth for user-generated content in the Web interface, like issues content, comments as well as permissions and credentials.

PostgreSQL can also hold some level of cached data like HTML rendered Markdown, cached merge-requests diff (this can also be configured to be offloaded to object storage).

We use PostgreSQL’s own replication functionality to replicate data from the primary to secondary nodes.

We use Redis both as a cache store and to hold persistent data for our background jobs system. Because both use-cases has data that are exclusive to the same Geo node, we don’t replicate it between nodes.

Elasticsearch is an optional database, that can enable advanced searching capabilities, like improved Global Search in both source-code level and user generated content in Issues / Merge-Requests and discussions. Currently it’s not supported in Geo.

Limitations on replication/verification

The following table lists the GitLab features along with their replication and verification status on a secondary node.

You can keep track of the progress to implement the missing items in these epics/issues:

Replicated data types behind a feature flag

The replication for some data types is behind a corresponding feature flag:

  • They’re deployed behind a feature flag, enabled by default.
  • They’re enabled on GitLab.com.
  • They can’t be enabled or disabled per-project.
  • They are recommended for production use.
  • For GitLab self-managed instances, GitLab administrators can opt to disable them.

Enable or disable replication (for some data types)

Replication for some data types are released behind feature flags that are enabled by default. GitLab administrators with access to the GitLab Rails console can opt to disable it for your instance. You can find feature flag names of each of those data types in the notes column of the table below.

To disable, such as for package file replication:

Feature.disable(:geo_package_file_replication)

To enable, such as for package file replication:

Feature.enable(:geo_package_file_replication)
Warning: Features not on this list, or with No in the Replicated column, are not replicated on the secondary node. Failing over without manually replicating data from those features will cause the data to be lost. If you wish to use those features on a secondary node, or to execute a failover successfully, you must replicate their data using some other means.
Feature Replicated (added in GitLab version) Verified (added in GitLab version) Object Storage replication (see Geo with Object Storage) Notes
Application data in PostgreSQL Yes (10.2) Yes (10.2) No  
Project repository Yes (10.2) Yes (10.7) No  
Project wiki repository Yes (10.2) Yes (10.7) No  
Group wiki repository No No No  
Uploads Yes (10.2) No No Verified only on transfer or manually using Integrity Check Rake Task on both nodes and comparing the output between them.
LFS objects Yes (10.2) No Via Object Storage provider if supported. Native Geo support (Beta). Verified only on transfer or manually using Integrity Check Rake Task on both nodes and comparing the output between them. GitLab versions 11.11.x and 12.0.x are affected by a bug that prevents any new LFS objects from replicating.
Personal snippets Yes (10.2) Yes (10.2) No  
Project snippets Yes (10.2) Yes (10.2) No  
CI job artifacts (other than Job Logs) Yes (10.4) No Via Object Storage provider if supported. Native Geo support (Beta) . Verified only manually using Integrity Check Rake Task on both nodes and comparing the output between them
Job logs Yes (10.4) No Via Object Storage provider if supported. Native Geo support (Beta). Verified only on transfer or manually using Integrity Check Rake Task on both nodes and comparing the output between them
Object pools for forked project deduplication Yes No No  
Container Registry Yes (12.3) No No Disabled by default. See instructions to enable.
Content in object storage (beta) Yes (12.4) No No  
Project designs repository Yes (12.7) No Via Object Storage provider if supported. Native Geo support (Beta).  
NPM Registry Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
Maven Repository Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
Conan Repository Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
NuGet Repository Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
PyPI Repository Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
Composer Repository Yes (13.2) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
Generic packages Yes (13.5) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_package_file_replication, enabled by default
Versioned Terraform State Yes (13.5) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_terraform_state_version_replication, enabled by default
External merge request diffs Yes (13.5) No Via Object Storage provider if supported. Native Geo support (Beta). Behind feature flag geo_merge_request_diff_replication, enabled by default
Versioned snippets No No No  
Server-side Git hooks No No No  
Elasticsearch integration No No No  
GitLab Pages No No No  
CI Pipeline Artifacts No No Via Object Storage provider if supported. Native Geo support (Beta). Persists additional artifacts after a pipeline completes
Dependency proxy images No No No Blocked on Geo: Secondary Mimicry. Note that replication of this cache is not needed for Disaster Recovery purposes because it can be recreated from external sources.
Vulnerability Export Not planned No Via Object Storage provider if supported. Native Geo support (Beta). Not planned because they are ephemeral and sensitive. They can be regenerated on demand.