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Geo (PREMIUM SELF)

Geo is the solution for widely distributed development teams and for providing a warm-standby as part of a disaster recovery strategy.

Overview

WARNING: Geo undergoes significant changes from release to release. Upgrades are supported and documented, but you should ensure that you're using the right version of the documentation for your installation.

Fetching large repositories can take a long time for teams located far from a single GitLab instance.

Geo provides local, read-only instances of your GitLab instances. This can reduce the time it takes to clone and fetch large repositories, speeding up development.

For a video introduction to Geo, see Introduction to GitLab Geo - GitLab Features.

To make sure you're using the right version of the documentation, navigate to the source version of this page on GitLab.com and choose the appropriate release from the Switch branch/tag dropdown. For example, v11.2.3-ee.

Use cases

Implementing Geo provides the following benefits:

  • Reduce from minutes to seconds the time taken for your distributed developers to clone and fetch large repositories and projects.
  • Enable all of your developers to contribute ideas and work in parallel, no matter where they are.
  • Balance the read-only load between your primary and secondary nodes.

In addition, it:

  • Can be used for cloning and fetching projects, in addition to reading any data available in the GitLab web interface (see limitations).
  • Overcomes slow connections between distant offices, saving time by improving speed for distributed teams.
  • Helps reducing the loading time for automated tasks, custom integrations, and internal workflows.
  • Can quickly fail over to a secondary node in a disaster recovery scenario.
  • Allows planned failover to a secondary node.

Geo provides:

  • Read-only secondary nodes: Maintain one primary GitLab node while still enabling read-only secondary nodes for each of your distributed teams.
  • Authentication system hooks: Secondary nodes receives all authentication data (like user accounts and logins) from the primary instance.
  • An intuitive UI: Secondary nodes use the same web interface your team has grown accustomed to. In addition, there are visual notifications that block write operations and make it clear that a user is on a secondary node.

Gitaly Cluster

Geo should not be confused with Gitaly Cluster. For more information about the difference between Geo and Gitaly Cluster, see Gitaly Cluster compared to Geo.

How it works

Your Geo instance can be used for cloning and fetching projects, in addition to reading any data. This will make working with large repositories over large distances much faster.

Geo overview

When Geo is enabled, the:

  • Original instance is known as the primary node.
  • Replicated read-only nodes are known as secondary nodes.

Keep in mind that:

  • Secondary nodes talk to the primary node to:
    • Get user data for logins (API).
    • Replicate repositories, LFS Objects, and Attachments (HTTPS + JWT).
  • In GitLab Premium 10.0 and later, the primary node no longer talks to secondary nodes to notify for changes (API).
  • Pushing directly to a secondary node (for both HTTP and SSH, including Git LFS) was introduced in GitLab Premium 11.3.
  • There are limitations when using Geo.

Architecture

The following diagram illustrates the underlying architecture of Geo.

Geo architecture

In this diagram:

  • There is the primary node and the details of one secondary node.
  • Writes to the database can only be performed on the primary node. A secondary node receives database updates via PostgreSQL streaming replication.
  • If present, the LDAP server should be configured to replicate for Disaster Recovery scenarios.
  • A secondary node performs different type of synchronizations against the primary node, using a special authorization protected by JWT:
    • Repositories are cloned/updated via Git over HTTPS.
    • Attachments, LFS objects, and other files are downloaded via HTTPS using a private API endpoint.

From the perspective of a user performing Git operations:

  • The primary node behaves as a full read-write GitLab instance.
  • Secondary nodes are read-only but proxy Git push operations to the primary node. This makes secondary nodes appear to support push operations themselves.

To simplify the diagram, some necessary components are omitted. Note that:

Note that a secondary node needs two different PostgreSQL databases:

  • A read-only database instance that streams data from the main GitLab database.
  • Another database instance used internally by the secondary node to record what data has been replicated.

In secondary nodes, there is an additional daemon: Geo Log Cursor.

Requirements for running Geo

The following are required to run Geo:

Additionally, check the GitLab minimum requirements, and we recommend you use:

  • At least GitLab Enterprise Edition 10.0 for basic Geo features.
  • The latest version for a better experience.

Firewall rules

The following table lists basic ports that must be open between the primary and secondary nodes for Geo.

Primary node Secondary node Protocol
80 80 HTTP
443 443 TCP or HTTPS
22 22 TCP
5432 PostgreSQL

See the full list of ports used by GitLab in Package defaults

NOTE: Web terminal support requires your load balancer to correctly handle WebSocket connections. When using HTTP or HTTPS proxying, your load balancer must be configured to pass through the Connection and Upgrade hop-by-hop headers. See the web terminal integration guide for more details.

NOTE: When using HTTPS protocol for port 443, you will need to add an SSL certificate to the load balancers. If you wish to terminate SSL at the GitLab application server instead, use TCP protocol.

LDAP

We recommend that if you use LDAP on your primary node, you also set up secondary LDAP servers on each secondary node. Otherwise, users will not be able to perform Git operations over HTTP(s) on the secondary node using HTTP Basic Authentication. However, Git via SSH and personal access tokens will still work.

NOTE: It is possible for all secondary nodes to share an LDAP server, but additional latency can be an issue. Also, consider what LDAP server will be available in a disaster recovery scenario if a secondary node is promoted to be a primary node.

Check for instructions on how to set up replication in your LDAP service. Instructions will be different depending on the software or service used. For example, OpenLDAP provides these instructions.

Geo Tracking Database

The tracking database instance is used as metadata to control what needs to be updated on the disk of the local instance. For example:

  • Download new assets.
  • Fetch new LFS Objects.
  • Fetch changes from a repository that has recently been updated.

Because the replicated database instance is read-only, we need this additional database instance for each secondary node.

Geo Log Cursor

This daemon:

  • Reads a log of events replicated by the primary node to the secondary database instance.
  • Updates the Geo Tracking Database instance with changes that need to be executed.

When something is marked to be updated in the tracking database instance, asynchronous jobs running on the secondary node will execute the required operations and update the state.

This new architecture allows GitLab to be resilient to connectivity issues between the nodes. It doesn't matter how long the secondary node is disconnected from the primary node as it will be able to replay all the events in the correct order and become synchronized with the primary node again.

Setup instructions

For setup instructions, see Setting up Geo.

Post-installation documentation

After installing GitLab on the secondary nodes and performing the initial configuration, see the following documentation for post-installation information.

Configuring Geo

For information on configuring Geo, see Geo configuration.

Updating Geo

For information on how to update your Geo nodes to the latest GitLab version, see Updating the Geo nodes.

Pausing and resuming replication

Introduced in GitLab Premium 13.2.

WARNING: In GitLab 13.2 and 13.3, promoting a secondary node to a primary while the secondary is paused fails. Do not pause replication before promoting a secondary. If the node is paused, be sure to resume before promoting. This issue has been fixed in GitLab 13.4 and later.

WARNING: Pausing and resuming of replication is currently only supported for Geo installations using an Omnibus GitLab-managed database. External databases are currently not supported.

In some circumstances, like during upgrades or a planned failover, it is desirable to pause replication between the primary and secondary.

Pausing and resuming replication is done via a command line tool from the secondary node where the postgresql service is enabled.

If postgresql is on a standalone database node, ensure that gitlab.rb on that node contains the configuration line gitlab_rails['geo_node_name'] = 'node_name', where node_name is the same as the geo_name_name on the application node.

To Pause: (from secondary)

gitlab-ctl geo-replication-pause

To Resume: (from secondary)

gitlab-ctl geo-replication-resume

Configuring Geo for multiple nodes

For information on configuring Geo for multiple nodes, see Geo for multiple servers.

Configuring Geo with Object Storage

For information on configuring Geo with object storage, see Geo with Object storage.

Disaster Recovery

For information on using Geo in disaster recovery situations to mitigate data-loss and restore services, see Disaster Recovery.

Replicating the Container Registry

For more information on how to replicate the Container Registry, see Docker Registry for a secondary node.

Security Review

For more information on Geo security, see Geo security review.

Tuning Geo

For more information on tuning Geo, see Tuning Geo.

Set up a location-aware Git URL

For an example of how to set up a location-aware Git remote URL with AWS Route53, see Location-aware Git remote URL with AWS Route53.

Backfill

Once a secondary node is set up, it will start replicating missing data from the primary node in a process known as backfill. You can monitor the synchronization process on each Geo node from the primary node's Geo Nodes dashboard in your browser.

Failures that happen during a backfill are scheduled to be retried at the end of the backfill.

Remove Geo node

For more information on removing a Geo node, see Removing secondary Geo nodes.

Disable Geo

To find out how to disable Geo, see Disabling Geo.

Limitations

WARNING: This list of limitations only reflects the latest version of GitLab. If you are using an older version, extra limitations may be in place.

  • Pushing directly to a secondary node redirects (for HTTP) or proxies (for SSH) the request to the primary node instead of handling it directly, except when using Git over HTTP with credentials embedded within the URI. For example, https://user:password@secondary.tld.
  • Cloning, pulling, or pushing repositories that exist on the primary node but not on the secondary nodes where selective synchronization does not include the project is not supported over SSH but support is planned. HTTP(S) is supported.
  • The primary node has to be online for OAuth login to happen. Existing sessions and Git are not affected. Support for the secondary node to use an OAuth provider independent from the primary is being planned.
  • The installation takes multiple manual steps that together can take about an hour depending on circumstances. We are working on improving this experience. See Omnibus GitLab issue #2978 for details.
  • Real-time updates of issues/merge requests (for example, via long polling) doesn't work on the secondary node.
  • Selective synchronization applies only to files and repositories. Other datasets are replicated to the secondary node in full, making it inappropriate for use as an access control mechanism.
  • Object pools for forked project deduplication work only on the primary node, and are duplicated on the secondary node.
  • GitLab Runners cannot register with a secondary node. Support for this is planned for the future.
  • Geo secondary nodes can not be configured to use high-availability configurations of PostgreSQL.

Limitations on replication/verification

There is a complete list of all GitLab data types and existing support for replication and verification.

Frequently Asked Questions

For answers to common questions, see the Geo FAQ.

Log files

In GitLab 9.5 and later, Geo stores structured log messages in a geo.log file. For Omnibus installations, this file is at /var/log/gitlab/gitlab-rails/geo.log.

This file contains information about when Geo attempts to sync repositories and files. Each line in the file contains a separate JSON entry that can be ingested into. For example, Elasticsearch or Splunk.

For example:

{"severity":"INFO","time":"2017-08-06T05:40:16.104Z","message":"Repository update","project_id":1,"source":"repository","resync_repository":true,"resync_wiki":true,"class":"Gitlab::Geo::LogCursor::Daemon","cursor_delay_s":0.038}

This message shows that Geo detected that a repository update was needed for project 1.

Troubleshooting

For troubleshooting steps, see Geo Troubleshooting.