gitlab-org--gitlab-foss/doc/administration/gitaly/index.md

Gitaly

Gitaly is the service that provides high-level RPC access to Git repositories. Without it, no other components can read or write Git data.

GitLab components that access Git repositories (gitlab-rails, gitlab-shell, gitlab-workhorse) act as clients to Gitaly. End users do not have direct access to Gitaly.

Configuring Gitaly

The Gitaly service itself is configured via a TOML configuration file. This file is documented in the gitaly repository.

To change a Gitaly setting in Omnibus you can use gitaly['my_setting'] in /etc/gitlab/gitlab.rb. Changes will be applied when you run gitlab-ctl reconfigure.

gitaly['prometheus_listen_addr'] = 'localhost:9236'

To change a Gitaly setting in installations from source you can edit /home/git/gitaly/config.toml. Changes will be applied when you run service gitlab restart.

prometheus_listen_addr = "localhost:9236"

Client-side GRPC logs

Gitaly uses the gRPC RPC framework. The Ruby gRPC client has its own log file which may contain useful information when you are seeing Gitaly errors. You can control the log level of the gRPC client with the GRPC_LOG_LEVEL environment variable. The default level is WARN.

Running Gitaly on its own server

This is an optional way to deploy Gitaly which can benefit GitLab installations that are larger than a single machine. Most installations will be better served with the default configuration used by Omnibus and the GitLab source installation guide.

Starting with GitLab 11.4, Gitaly is able to serve all Git requests without needed a shared NFS mount for Git repository data. Between 11.4 and 11.8 the exception was the Elastic Search indexer. But since 11.8 the indexer uses Gitaly for data access as well. NFS can still be leveraged for redudancy on block level of the Git data. But only has to be mounted on the Gitaly server.

Network architecture

• gitlab-rails shards repositories into "repository storages"
• gitlab-rails/config/gitlab.yml contains a map from storage names to (Gitaly address, Gitaly token) pairs
• the storage name -> (Gitaly address, Gitaly token) map in gitlab.yml is the single source of truth for the Gitaly network topology
• a (Gitaly address, Gitaly token) corresponds to a Gitaly server
• a Gitaly server hosts one or more storages
• Gitaly addresses must be specified in such a way that they resolve correctly for ALL Gitaly clients
• Gitaly clients are: unicorn, sidekiq, gitlab-workhorse, gitlab-shell, Elasticsearch Indexer, and Gitaly itself
• special case: a Gitaly server must be able to make RPC calls to itself via its own (Gitaly address, Gitaly token) pair as specified in gitlab-rails/config/gitlab.yml
• Gitaly servers must not be exposed to the public internet

Gitaly network traffic is unencrypted by default, but supports TLS. Authentication is done through a static token. For security in depth, its recommended to use a firewall to restrict access to your Gitaly server.

Below we describe how to configure a Gitaly server at address gitaly.internal:8075 with secret token abc123secret. We assume your GitLab installation has two repository storages, default and storage1.

Client side token configuration

Start by configuring a token on the client side.

Omnibus installations:

# /etc/gitlab/gitlab.rb
gitlab_rails['gitaly_token'] = 'abc123secret'

Source installations:

# /home/git/gitlab/config/gitlab.yml
gitlab:
  gitaly:
    token: 'abc123secret'

You need to reconfigure (Omnibus) or restart (source) for these changes to be picked up.

Gitaly server configuration

Next, on the Gitaly server, we need to configure storage paths, enable the network listener and configure the token.

Note: if you want to reduce the risk of downtime when you enable authentication you can temporarily disable enforcement, see the documentation on configuring Gitaly authentication .

Gitaly must trigger some callbacks to GitLab via GitLab Shell. As a result, the GitLab Shell secret must be the same between the other GitLab servers and the Gitaly server. The easiest way to accomplish this is to copy /etc/gitlab/gitlab-secrets.json from an existing GitLab server to the Gitaly server. Without this shared secret, Git operations in GitLab will result in an API error.

NOTE: In most or all cases the storage paths below end in /repositories which is different than path in git_data_dirs of Omnibus installations. Check the directory layout on your Gitaly server to be sure.

Omnibus installations:

# /etc/gitlab/gitlab.rb

# Avoid running unnecessary services on the Gitaly server
postgresql['enable'] = false
redis['enable'] = false
nginx['enable'] = false
prometheus['enable'] = false
unicorn['enable'] = false
sidekiq['enable'] = false
gitlab_workhorse['enable'] = false

# Prevent database connections during 'gitlab-ctl reconfigure'
gitlab_rails['rake_cache_clear'] = false
gitlab_rails['auto_migrate'] = false

# Configure the gitlab-shell API callback URL. Without this, `git push` will
# fail. This can be your 'front door' GitLab URL or an internal load
# balancer.
gitlab_rails['internal_api_url'] = 'https://gitlab.example.com'

# Make Gitaly accept connections on all network interfaces. You must use
# firewalls to restrict access to this address/port.
gitaly['listen_addr'] = "0.0.0.0:8075"
gitaly['auth_token'] = 'abc123secret'

gitaly['storage'] = [
  { 'name' => 'default', 'path' => '/mnt/gitlab/default/repositories' },
  { 'name' => 'storage1', 'path' => '/mnt/gitlab/storage1/repositories' },
]

# To use TLS for Gitaly you need to add
gitaly['tls_listen_addr'] = "0.0.0.0:9999"
gitaly['certificate_path'] = "path/to/cert.pem"
gitaly['key_path'] = "path/to/key.pem"

Source installations:

# /home/git/gitaly/config.toml
listen_addr = '0.0.0.0:8075'
tls_listen_addr = '0.0.0.0:9999'

[tls]
certificate_path = /path/to/cert.pem
key_path = /path/to/key.pem

[auth]
token = 'abc123secret'

[[storage]]
name = 'default'
path = '/mnt/gitlab/default/repositories'

[[storage]]
name = 'storage1'
path = '/mnt/gitlab/storage1/repositories'

Again, reconfigure (Omnibus) or restart (source).

Converting clients to use the Gitaly server

Now as the final step update the client machines to switch from using their local Gitaly service to the new Gitaly server you just configured. This is a risky step because if there is any sort of network, firewall, or name resolution problem preventing your GitLab server from reaching the Gitaly server then all Gitaly requests will fail.

We assume that your Gitaly server can be reached at gitaly.internal:8075 from your GitLab server, and that Gitaly can read and write to /mnt/gitlab/default and /mnt/gitlab/storage1 respectively.

Omnibus installations:

# /etc/gitlab/gitlab.rb
git_data_dirs({
  'default' => { 'gitaly_address' => 'tcp://gitaly.internal:8075' },
  'storage1' => { 'gitaly_address' => 'tcp://gitaly.internal:8075' },
})

gitlab_rails['gitaly_token'] = 'abc123secret'

Source installations:

# /home/git/gitlab/config/gitlab.yml
gitlab:
  repositories:
    storages:
      default:
        gitaly_address: tcp://gitaly.internal:8075
      storage1:
        gitaly_address: tcp://gitaly.internal:8075

  gitaly:
    token: 'abc123secret'

Now reconfigure (Omnibus) or restart (source). When you tail the Gitaly logs on your Gitaly server (sudo gitlab-ctl tail gitaly or tail -f /home/git/gitlab/log/gitaly.log) you should see requests coming in. One sure way to trigger a Gitaly request is to clone a repository from your GitLab server over HTTP.

TLS support

Introduced in GitLab 11.8.

Gitaly supports TLS encryption. To be able to communicate with a Gitaly instance that listens for secure connections you will need to use tls:// url scheme in the gitaly_address of the corresponding storage entry in the gitlab configuration.

The admin needs to bring their own certificate as we do not provide that automatically. The certificate to be used needs to be installed on all Gitaly nodes and on all client nodes that communicate with it following procedures described in GitLab custom certificate configuration.

Note that it is possible to configure Gitaly servers with both an unencrypted listening address listen_addr and an encrypted listening address tls_listen_addr at the same time. This allows you to do a gradual transition from unencrypted to encrypted traffic, if necessary.

To observe what type of connections are actually being used in a production environment you can use the following Prometheus query:

sum(rate(gitaly_connections_total[5m])) by (type)

Example TLS configuration

Omnibus installations:

On client nodes:

# /etc/gitlab/gitlab.rb
git_data_dirs({
  'default' => { 'path' => '/mnt/gitlab/default', 'gitaly_address' => 'tls://gitaly.internal:9999' },
  'storage1' => { 'path' => '/mnt/gitlab/storage1', 'gitaly_address' => 'tls://gitaly.internal:9999' },
})

gitlab_rails['gitaly_token'] = 'abc123secret'

On Gitaly server nodes:

gitaly['tls_listen_addr'] = "0.0.0.0:9999"
gitaly['certificate_path'] = "path/to/cert.pem"
gitaly['key_path'] = "path/to/key.pem"

Source installations:

On client nodes:

# /home/git/gitlab/config/gitlab.yml
gitlab:
  repositories:
    storages:
      default:
        path: /mnt/gitlab/default/repositories
        gitaly_address: tls://gitaly.internal:9999
      storage1:
        path: /mnt/gitlab/storage1/repositories
        gitaly_address: tls://gitaly.internal:9999

  gitaly:
    token: 'abc123secret'

On Gitaly server nodes:

# /home/git/gitaly/config.toml
tls_listen_addr = '0.0.0.0:9999'

[tls]
certificate_path = '/path/to/cert.pem'
key_path = '/path/to/key.pem'

Gitaly-ruby

Gitaly was developed to replace Ruby application code in gitlab-ce/ee. In order to save time and/or avoid the risk of rewriting existing application logic, in some cases we chose to copy some application code from gitlab-ce into Gitaly almost as-is. To be able to run that code, we made gitaly-ruby, which is a sidecar process for the main Gitaly Go process. Some examples of things that are implemented in gitaly-ruby are RPC's that deal with wiki's, and RPC's that create commits on behalf of a user, such as merge commits.

Number of gitaly-ruby workers

Gitaly-ruby has much less capacity than Gitaly itself. If your Gitaly server has to handle a lot of request, the default setting of having just 1 active gitaly-ruby sidecar might not be enough. If you see ResourceExhausted errors from Gitaly it's very likely that you have not enough gitaly-ruby capacity.

You can increase the number of gitaly-ruby processes on your Gitaly server with the following settings.

Omnibus:

# /etc/gitlab/gitlab.rb
# Default is 2 workers. The minimum is 2; 1 worker is always reserved as
# a passive stand-by.
gitaly['ruby_num_workers'] = 4

Source:

# /home/git/gitaly/config.toml
[gitaly-ruby]
num_workers = 4

Observing gitaly-ruby traffic

Gitaly-ruby is a somewhat hidden, internal implementation detail of Gitaly. There is not that much visibility into what goes on inside gitaly-ruby processes.

If you have Prometheus set up to scrape your Gitaly process, you can see request rates and error codes for individual RPC's in gitaly-ruby by querying grpc_client_handled_total. Strictly speaking this metric does not differentiate between gitaly-ruby and other RPC's, but in practice (as of GitLab 11.9), all gRPC calls made by Gitaly itself are internal calls from the main Gitaly process to one of its gitaly-ruby sidecars.

Assuming your grpc_client_handled_total counter only observes Gitaly, the following query shows you RPC's are (most likely) internally implemented as calls to gitaly-ruby.

sum(rate(grpc_client_handled_total[5m])) by (grpc_method) > 0

Disabling or enabling the Gitaly service in a cluster environment

If you are running Gitaly as a remote service you may want to disable the local Gitaly service that runs on your GitLab server by default.

'Disabling Gitaly' only makes sense when you run GitLab in a custom cluster configuration, where different services run on different machines. Disabling Gitaly on all machines in the cluster is not a valid configuration.

If you are setting up a GitLab cluster where Gitaly does not need to run on all machines, you can disable the Gitaly service in your Omnibus installation, add the following line to /etc/gitlab/gitlab.rb:

gitaly['enable'] = false

When you run gitlab-ctl reconfigure the Gitaly service will be disabled.

To disable the Gitaly service in a GitLab cluster where you installed GitLab from source, add the following to /etc/default/gitlab on the machine where you want to disable Gitaly.

gitaly_enabled=false

When you run service gitlab restart Gitaly will be disabled on this particular machine.

Troubleshooting Gitaly in production

Since GitLab 11.6, Gitaly comes with a command-line tool called gitaly-debug that can be run on a Gitaly server to aid in troubleshooting. In GitLab 11.6 its only sub-command is simulate-http-clone which allows you to measure the maximum possible Git clone speed for a specific repository on the server.

For an up to date list of sub-commands see the gitaly-debug README.