Gitaly

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

In the Gitaly documentation:

Gitaly server refers to any node that runs Gitaly itself.
Gitaly client refers to any node that runs a process that makes requests of the Gitaly server. Processes include, but are not limited to:

GitLab end users do not have direct access to Gitaly. Gitaly only manages Git repository access for GitLab. Other types of GitLab data aren't accessed using Gitaly.

WARNING: From GitLab 13.0, Gitaly support for NFS is deprecated. As of GitLab 14.0, NFS-related issues with Gitaly will no longer be addressed. Upgrade to Gitaly Cluster as soon as possible. Tools to enable bulk moves of projects to Gitaly Cluster are planned.

Architecture

The following is a high-level architecture overview of how Gitaly is used.

Configure Gitaly

The Gitaly service itself is configured via a TOML configuration file.

To change Gitaly settings:

For Omnibus GitLab

Edit /etc/gitlab/gitlab.rb and add or change the Gitaly settings.
Save the file and reconfigure GitLab.

For installations from source

Edit /home/git/gitaly/config.toml and add or change the Gitaly settings.
Save the file and restart GitLab.

The following configuration options are also available:

Enabling TLS support.
Configuring the number of gitaly-ruby workers.
Limiting RPC concurrency.

Run Gitaly on its own server

By default, Gitaly is run on the same server as Gitaly clients and is configured as above. Single-server installations are best served by this default configuration used by:

Omnibus GitLab.
The GitLab source installation guide.

However, Gitaly can be deployed to its own server, which can benefit GitLab installations that span multiple machines.

NOTE: When configured to run on their own servers, Gitaly servers must be upgraded before Gitaly clients in your cluster.

The process for setting up Gitaly on its own server is:

Install Gitaly.
Configure authentication.
Configure Gitaly servers.
Configure Gitaly clients.
Disable Gitaly where not required (optional).

When running Gitaly on its own server, note the following regarding GitLab versions:

From GitLab 11.4, Gitaly was able to serve all Git requests without requiring a shared NFS mount for Git repository data, except for the Elasticsearch indexer.
From GitLab 11.8, the Elasticsearch indexer uses Gitaly for data access as well. NFS can still be leveraged for redundancy on block-level Git data, but only has to be mounted on the Gitaly servers.
From GitLab 11.8 to 12.2, it is possible to use Elasticsearch in a Gitaly setup that doesn't use NFS. To use Elasticsearch in these versions, the repository indexer must be enabled in your GitLab configuration.
In GitLab 12.3 and later, the new indexer is the default and no configuration is required.

Network architecture

The following list depicts the network architecture of Gitaly:

GitLab Rails shards repositories into repository storages.
/config/gitlab.yml contains a map from storage names to (Gitaly address, Gitaly token) pairs.
The storage name -> (Gitaly address, Gitaly token) map in /config/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.
A Gitaly client can use one or more Gitaly servers.
Gitaly addresses must be specified in such a way that they resolve correctly for all Gitaly clients.
Gitaly clients are:
- Puma or Unicorn.
- Sidekiq.
- GitLab Workhorse.
- GitLab Shell.
- Elasticsearch indexer.
- Gitaly itself.
A Gitaly server must be able to make RPC calls to itself via its own (Gitaly address, Gitaly token) pair as specified in /config/gitlab.yml.
Authentication is done through a static token which is shared among the Gitaly and GitLab Rails nodes.

WARNING: Gitaly servers must not be exposed to the public internet as Gitaly's network traffic is unencrypted by default. The use of firewall is highly recommended to restrict access to the Gitaly server. Another option is to use TLS.

In the following sections, we describe how to configure two Gitaly servers with secret token abc123secret:

gitaly1.internal.
gitaly2.internal.

We assume your GitLab installation has three repository storages:

default.
storage1.
storage2.

You can use as few as one server with one repository storage if desired.

NOTE: The token referred to throughout the Gitaly documentation is just an arbitrary password selected by the administrator. It is unrelated to tokens created for the GitLab API or other similar web API tokens.

Install Gitaly

Install Gitaly on each Gitaly server using either Omnibus GitLab or install it from source:

For Omnibus GitLab, download and install the Omnibus GitLab package you want but do not provide the EXTERNAL_URL= value.
To install from source, follow the steps at Install Gitaly.

Configure authentication

Gitaly and GitLab use two shared secrets for authentication:

One to authenticate gRPC requests to Gitaly.
A second for authentication callbacks from GitLab Shell to the GitLab internal API.

For Omnibus GitLab

To configure the Gitaly token:

On the Gitaly clients, edit /etc/gitlab/gitlab.rb:
```
gitlab_rails['gitaly_token'] = 'abc123secret'
```
Save the file and reconfigure GitLab.
On the Gitaly server, edit /etc/gitlab/gitlab.rb:
```
gitaly['auth_token'] = 'abc123secret'
```
Reconfigure GitLab.

There are two ways to configure the GitLab Shell token.

Method 1:

Copy /etc/gitlab/gitlab-secrets.json from the Gitaly client to same path on the Gitaly servers (and any other Gitaly clients).
Reconfigure GitLab on Gitaly servers.

Method 2:

On the Gitaly clients, edit /etc/gitlab/gitlab.rb:
```
gitlab_shell['secret_token'] = 'shellsecret'
```
Save the file and reconfigure GitLab.
On the Gitaly servers, edit /etc/gitlab/gitlab.rb:
```
gitlab_shell['secret_token'] = 'shellsecret'
```
Reconfigure GitLab.

For installations from source

Copy /home/git/gitlab/.gitlab_shell_secret from the Gitaly client to the same path on the Gitaly servers (and any other Gitaly clients).
On the Gitaly clients, edit /home/git/gitlab/config/gitlab.yml:
```
gitlab:
  gitaly:
    token: 'abc123secret'
```
Save the file and restart GitLab.
On the Gitaly servers, edit /home/git/gitaly/config.toml:
```
[auth]
token = 'abc123secret'
```
Save the file and restart GitLab.

Configure Gitaly servers

On the Gitaly servers, you must configure storage paths and enable the network listener.

If you want to reduce the risk of downtime when you enable authentication, you can temporarily disable enforcement. For more information, see the documentation on configuring Gitaly authentication.

For Omnibus GitLab

Edit /etc/gitlab/gitlab.rb:

# /etc/gitlab/gitlab.rb

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

# If you run a separate monitoring node you can disable these services
alertmanager['enable'] = false
prometheus['enable'] = false

# If you don't run a separate monitoring node you can
# enable Prometheus access & disable these extra services.
# This makes Prometheus listen on all interfaces. You must use firewalls to restrict access to this address/port.
# prometheus['listen_address'] = '0.0.0.0:9090'
# prometheus['monitor_kubernetes'] = false

# If you don't want to run monitoring services uncomment the following (not recommended)
# node_exporter['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.
# Don't forget to copy `/etc/gitlab/gitlab-secrets.json` from Gitaly client to Gitaly server.
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.
# Comment out following line if you only want to support TLS connections
gitaly['listen_addr'] = "0.0.0.0:8075"

Append the following to /etc/gitlab/gitlab.rb for each respective Gitaly server:

On gitaly1.internal:

git_data_dirs({
  'default' => {
    'path' => '/var/opt/gitlab/git-data'
  },
  'storage1' => {
    'path' => '/mnt/gitlab/git-data'
  },
})

On gitaly2.internal:

git_data_dirs({
  'storage2' => {
    'path' => '/srv/gitlab/git-data'
  },
})

Save the file and reconfigure GitLab.
Run sudo /opt/gitlab/embedded/bin/gitaly-hooks check /var/opt/gitlab/gitaly/config.toml to confirm that Gitaly can perform callbacks to the GitLab internal API.

For installations from source

Edit /home/git/gitaly/config.toml:

listen_addr = '0.0.0.0:8075'

internal_socket_dir = '/var/opt/gitlab/gitaly'

[logging]
format = 'json'
level = 'info'
dir = '/var/log/gitaly'

Append the following to /home/git/gitaly/config.toml for each respective Gitaly server:

On gitaly1.internal:

[[storage]]
name = 'default'
path = '/var/opt/gitlab/git-data/repositories'

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

On gitaly2.internal:

[[storage]]
name = 'storage2'
path = '/srv/gitlab/git-data/repositories'

Edit /home/git/gitlab-shell/config.yml:
```
gitlab_url: https://gitlab.example.com
```
Save the files and restart GitLab.
Run sudo -u git /home/git/gitaly/gitaly-hooks check /home/git/gitaly/config.toml to confirm that Gitaly can perform callbacks to the GitLab internal API.

Configure Gitaly clients

As the final step, you must update Gitaly clients to switch from using local Gitaly service to use the Gitaly servers you just configured.

This can be risky because anything that prevents your Gitaly clients from reaching the Gitaly servers causes all Gitaly requests to fail. For example, any sort of network, firewall, or name resolution problems.

Additionally, you must disable Rugged if previously enabled manually.

Gitaly makes the following assumptions:

Your gitaly1.internal Gitaly server can be reached at gitaly1.internal:8075 from your Gitaly clients, and that Gitaly server can read, write, and set permissions on /mnt/gitlab/default and /mnt/gitlab/storage1.
Your gitaly2.internal Gitaly server can be reached at gitaly2.internal:8075 from your Gitaly clients, and that Gitaly server can read, write, and set permissions on /mnt/gitlab/storage2.
Your gitaly1.internal and gitaly2.internal Gitaly servers can reach each other.

You can't define Gitaly servers with some as a local Gitaly server (without gitaly_address) and some as remote server (with gitaly_address) unless you use mixed configuration.

For Omnibus GitLab

Edit /etc/gitlab/gitlab.rb:

git_data_dirs({
  'default' => { 'gitaly_address' => 'tcp://gitaly1.internal:8075' },
  'storage1' => { 'gitaly_address' => 'tcp://gitaly1.internal:8075' },
  'storage2' => { 'gitaly_address' => 'tcp://gitaly2.internal:8075' },
})

Save the file and reconfigure GitLab.
Run sudo gitlab-rake gitlab:gitaly:check on the Gitaly client (for example, the Rails application) to confirm it can connect to Gitaly servers.
Tail the logs to see the requests:
```
sudo gitlab-ctl tail gitaly
```

For installations from source

Edit /home/git/gitlab/config/gitlab.yml:

gitlab:
  repositories:
    storages:
      default:
        gitaly_address: tcp://gitaly1.internal:8075
        path: /some/local/path
      storage1:
        gitaly_address: tcp://gitaly1.internal:8075
        path: /some/local/path
      storage2:
        gitaly_address: tcp://gitaly2.internal:8075
        path: /some/local/path

NOTE: /some/local/path should be set to a local folder that exists, however no data is stored in this folder. This requirement is scheduled to be removed when this issue is resolved.

Save the file and restart GitLab.
Run sudo -u git -H bundle exec rake gitlab:gitaly:check RAILS_ENV=production to confirm the Gitaly client can connect to Gitaly servers.
Tail the logs to see the requests:
```
tail -f /home/git/gitlab/log/gitaly.log
```

When you tail the Gitaly logs on your Gitaly server, you should see requests coming in. One sure way to trigger a Gitaly request is to clone a repository from GitLab over HTTP or HTTPS.

WARNING: If you have server hooks configured, either per repository or globally, you must move these to the Gitaly servers. If you have multiple Gitaly servers, copy your server hooks to all Gitaly servers.

Mixed configuration

GitLab can reside on the same server as one of many Gitaly servers, but doesn't support configuration that mixes local and remote configuration. The following setup is incorrect, because:

All addresses must be reachable from the other Gitaly servers.
storage1 is assigned a Unix socket for gitaly_address which is invalid for some of the Gitaly servers.

git_data_dirs({
  'default' => { 'gitaly_address' => 'tcp://gitaly1.internal:8075' },
  'storage1' => { 'path' => '/mnt/gitlab/git-data' },
  'storage2' => { 'gitaly_address' => 'tcp://gitaly2.internal:8075' },
})

To combine local and remote Gitaly servers, use an external address for the local Gitaly server. For example:

git_data_dirs({
  'default' => { 'gitaly_address' => 'tcp://gitaly1.internal:8075' },
  # Address of the GitLab server that has Gitaly running on it
  'storage1' => { 'gitaly_address' => 'tcp://gitlab.internal:8075', 'path' => '/mnt/gitlab/git-data' },
  'storage2' => { 'gitaly_address' => 'tcp://gitaly2.internal:8075' },
})

# Make Gitaly accept connections on all network interfaces
gitaly['listen_addr'] = "0.0.0.0:8075"

# Or for TLS
gitaly['tls_listen_addr'] = "0.0.0.0:9999"
gitaly['certificate_path'] = "/etc/gitlab/ssl/cert.pem"
gitaly['key_path'] = "/etc/gitlab/ssl/key.pem"

path can only be included for storage shards on the local Gitaly server. If it's excluded, default Git storage directory is used for that storage shard.

Disable Gitaly where not required (optional)

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 and have it only running where required.

Disabling Gitaly on the GitLab instance only makes sense when you run GitLab in a custom cluster configuration, where Gitaly runs on a separate machine from the GitLab instance. Disabling Gitaly on all machines in the cluster is not a valid configuration (some machines much act as Gitaly servers).

To disable Gitaly on a GitLab server:

For Omnibus GitLab

Edit /etc/gitlab/gitlab.rb:
```
gitaly['enable'] = false
```
Save the file and reconfigure GitLab.

For installations from source

Edit /etc/default/gitlab:
```
gitaly_enabled=false
```
Save the file and restart GitLab.

Enable TLS support

Introduced in GitLab 11.8.

Introduced in GitLab 13.6, outgoing TLS connections to GitLab provide client certificates if configured.

Gitaly supports TLS encryption. To communicate with a Gitaly instance that listens for secure connections, you must use tls:// URL scheme in the gitaly_address of the corresponding storage entry in the GitLab configuration.

Gitaly provides the same server certificates as client certificates in TLS connections to GitLab. This can be used as part of a mutual TLS authentication strategy when combined with reverse proxies (for example, NGINX) that validate client certificate to grant access to GitLab.

You must supply your own certificates as this isn't provided automatically. The certificate corresponding to each Gitaly server must be installed on that Gitaly server.

Additionally, the certificate (or its certificate authority) must be installed on all:

Gitaly servers.
Gitaly clients that communicate with it.

Note the following:

The certificate must specify the address you use to access the Gitaly server. You must add the hostname or IP address as a Subject Alternative Name to the certificate.
You can 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 gradually transition from unencrypted to encrypted traffic if necessary.

To configure Gitaly with TLS:

For Omnibus GitLab

Create certificates for Gitaly servers.
On the Gitaly clients, copy the certificates (or their certificate authority) into /etc/gitlab/trusted-certs:
```
sudo cp cert.pem /etc/gitlab/trusted-certs/
```

On the Gitaly clients, edit git_data_dirs in /etc/gitlab/gitlab.rb as follows:

git_data_dirs({
  'default' => { 'gitaly_address' => 'tls://gitaly1.internal:9999' },
  'storage1' => { 'gitaly_address' => 'tls://gitaly1.internal:9999' },
  'storage2' => { 'gitaly_address' => 'tls://gitaly2.internal:9999' },
})

Save the file and reconfigure GitLab.

On the Gitaly servers, create the /etc/gitlab/ssl directory and copy your key and certificate there:

sudo mkdir -p /etc/gitlab/ssl
sudo chmod 755 /etc/gitlab/ssl
sudo cp key.pem cert.pem /etc/gitlab/ssl/
sudo chmod 644 key.pem cert.pem

Copy all Gitaly server certificates (or their certificate authority) to /etc/gitlab/trusted-certs so that Gitaly servers trust the certificate when calling into themselves or other Gitaly servers:
```
sudo cp cert1.pem cert2.pem /etc/gitlab/trusted-certs/
```

Edit /etc/gitlab/gitlab.rb and add:

gitaly['tls_listen_addr'] = "0.0.0.0:9999"
gitaly['certificate_path'] = "/etc/gitlab/ssl/cert.pem"
gitaly['key_path'] = "/etc/gitlab/ssl/key.pem"

Save the file and reconfigure GitLab.
Verify Gitaly traffic is being served over TLS by observing the types of Gitaly connections.
(Optional) Improve security by:
1. Disabling non-TLS connections by commenting out or deleting gitaly['listen_addr'] in /etc/gitlab/gitlab.rb.
2. Saving the file.
3. Reconfiguring GitLab.

For installations from source

Create certificates for Gitaly servers.

On the Gitaly clients, copy the certificates into the system trusted certificates:

sudo cp cert.pem /usr/local/share/ca-certificates/gitaly.crt
sudo update-ca-certificates

On the Gitaly clients, edit storages in /home/git/gitlab/config/gitlab.yml as follows:

gitlab:
  repositories:
    storages:
      default:
        gitaly_address: tls://gitaly1.internal:9999
        path: /some/local/path
      storage1:
        gitaly_address: tls://gitaly1.internal:9999
        path: /some/local/path
      storage2:
        gitaly_address: tls://gitaly2.internal:9999
        path: /some/local/path

NOTE: /some/local/path should be set to a local folder that exists, however no data is stored in this folder. This requirement is scheduled to be removed when Gitaly issue #1282 is resolved.

Save the file and restart GitLab.
On the Gitaly servers, create or edit /etc/default/gitlab and add:
```
export SSL_CERT_DIR=/etc/gitlab/ssl
```

On the Gitaly servers, create the /etc/gitlab/ssl directory and copy your key and certificate there:

sudo mkdir -p /etc/gitlab/ssl
sudo chmod 755 /etc/gitlab/ssl
sudo cp key.pem cert.pem /etc/gitlab/ssl/
sudo chmod 644 key.pem cert.pem

Copy all Gitaly server certificates (or their certificate authority) to the system trusted certificates folder so Gitaly server trusts the certificate when calling into itself or other Gitaly servers.
```
sudo cp cert.pem /usr/local/share/ca-certificates/gitaly.crt
sudo update-ca-certificates
```

Edit /home/git/gitaly/config.toml and add:

tls_listen_addr = '0.0.0.0:9999'

[tls]
certificate_path = '/etc/gitlab/ssl/cert.pem'
key_path = '/etc/gitlab/ssl/key.pem'

Save the file and restart GitLab.
Verify Gitaly traffic is being served over TLS by observing the types of Gitaly connections.
(Optional) Improve security by:
1. Disabling non-TLS connections by commenting out or deleting listen_addr in /home/git/gitaly/config.toml.
2. Saving the file.
3. Restarting GitLab.

Observe type of Gitaly connections

Prometheus can be used observe what type of connections Gitaly is serving a production environment. Use the following Prometheus query:

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

`gitaly-ruby`

Gitaly was developed to replace the Ruby application code in GitLab.

To save time and avoid the risk of rewriting existing application logic, we chose to copy some application code from GitLab into Gitaly.

To be able to run that code, gitaly-ruby was created, which is a "sidecar" process for the main Gitaly Go process. Some examples of things that are implemented in gitaly-ruby are:

RPCs that deal with wikis.
RPCs that create commits on behalf of a user, such as merge commits.

We recommend:

At least 300MB memory per worker.
No more than one worker per core.

NOTE: gitaly-ruby is planned to be eventually removed. To track progress, see the Remove the Gitaly-Ruby sidecar epic.

Configure number of `gitaly-ruby` workers

gitaly-ruby has much less capacity than Gitaly implemented in Go. If your Gitaly server has to handle lots of requests, the default setting of having just one 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:

For Omnibus GitLab

Edit /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

Save the file and reconfigure GitLab.

For installations from source

Edit /home/git/gitaly/config.toml:
```
[gitaly-ruby]
num_workers = 4
```
Save the file and restart GitLab.

Limit RPC concurrency

Clone traffic can put a large strain on your Gitaly service. The bulk of the work gets done in the either of the following RPCs:

SSHUploadPack (for Git SSH).
PostUploadPack (for Git HTTP).

To prevent such workloads from overwhelming your Gitaly server, you can set concurrency limits in Gitaly's configuration file. For example:

# in /etc/gitlab/gitlab.rb

gitaly['concurrency'] = [
  {
    'rpc' => "/gitaly.SmartHTTPService/PostUploadPack",
    'max_per_repo' => 20
  },
  {
    'rpc' => "/gitaly.SSHService/SSHUploadPack",
    'max_per_repo' => 20
  }
]

This limits the number of in-flight RPC calls for the given RPCs. The limit is applied per repository. In the example above:

Each repository served by the Gitaly server can have at most 20 simultaneous PostUploadPack RPC calls in flight, and the same for SSHUploadPack.
If another request comes in for a repository that has used up its 20 slots, that request gets queued.

You can observe the behavior of this queue using the Gitaly logs and Prometheus:

In the Gitaly logs, look for the string (or structured log field) acquire_ms. Messages that have this field are reporting about the concurrency limiter.
In Prometheus, look for the following metrics:
- gitaly_rate_limiting_in_progress.
- gitaly_rate_limiting_queued.
- gitaly_rate_limiting_seconds.

NOTE: Though the name of the Prometheus metric contains rate_limiting, it is a concurrency limiter, not a rate limiter. If a Gitaly client makes 1000 requests in a row very quickly, concurrency does not exceed 1 and the concurrency limiter has no effect.

Rotate Gitaly authentication token

Rotating credentials in a production environment often requires downtime, causes outages, or both.

However, you can rotate Gitaly credentials without a service interruption. Rotating a Gitaly authentication token involves:

Verifying authentication monitoring.
Enabling "auth transitioning" mode.
Updating Gitaly authentication tokens.
Ensuring there are no authentication failures.
Disabling "auth transitioning" mode.
Verifying authentication is enforced.

This procedure also works if you are running GitLab on a single server. In that case, "Gitaly server" and "Gitaly client" refers to the same machine.

Verify authentication monitoring

Before rotating a Gitaly authentication token, verify that you can monitor the authentication behavior of your GitLab installation using Prometheus. Use the following Prometheus query:

sum(rate(gitaly_authentications_total[5m])) by (enforced, status)

In a system where authentication is configured correctly and where you have live traffic, you see something like this:

{enforced="true",status="ok"}  4424.985419441742

There may also be other numbers with rate 0. We only care about the non-zero numbers.

The only non-zero number should have enforced="true",status="ok". If you have other non-zero numbers, something is wrong in your configuration.

The status="ok" number reflects your current request rate. In the example above, Gitaly is handling about 4000 requests per second.

Now that you have established that you can monitor the Gitaly authentication behavior of your GitLab installation, you can begin the rest of the procedure.

Enable "auth transitioning" mode

Temporarily disable Gitaly authentication on the Gitaly servers by putting them into "auth transitioning" mode as follows:

# in /etc/gitlab/gitlab.rb
gitaly['auth_transitioning'] = true

After you have made this change, your Prometheus query should return something like:

{enforced="false",status="would be ok"}  4424.985419441742

Because enforced="false", it is safe to start rolling out the new token.

Update Gitaly authentication token

To update to a new Gitaly authentication token, on each Gitaly client and Gitaly server:

Update the configuration:

# in /etc/gitlab/gitlab.rb

gitaly['auth_token'] = '<new secret token>'

Restart Gitaly:
```
gitlab-ctl restart gitaly
```

If you run your Prometheus query while this change is being rolled out, you see non-zero values for the enforced="false",status="denied" counter.

Ensure there are no authentication failures

After the new token is set, and all services involved have been restarted, you will temporarily see a mix of:

status="would be ok".
status="denied".

After the new token has been picked up by all Gitaly clients and Gitaly servers, the only non-zero rate should be enforced="false",status="would be ok".

Disable "auth transitioning" mode

To re-enable Gitaly authentication, disable "auth transitioning" mode. Update the configuration on your Gitaly servers as follows:

# in /etc/gitlab/gitlab.rb
gitaly['auth_transitioning'] = false

WARNING: Without completing this step, you have no Gitaly authentication.

Verify authentication is enforced

Refresh your Prometheus query. You should now see a similar result as you did at the start. For example:

{enforced="true",status="ok"}  4424.985419441742

Note that enforced="true" means that authentication is being enforced.

Direct Git access bypassing Gitaly

While it is possible to access Gitaly repositories stored on disk directly with a Git client, it is not advisable because Gitaly is being continuously improved and changed. Theses improvements may invalidate assumptions, resulting in performance degradation, instability, and even data loss.

Gitaly has optimizations, such as the info/refs advertisement cache, that rely on Gitaly controlling and monitoring access to repositories via the official gRPC interface. Likewise, Praefect has optimizations, such as fault tolerance and distributed reads, that depend on the gRPC interface and database to determine repository state.

For these reasons, accessing repositories directly is done at your own risk and is not supported.

Direct access to Git in GitLab

Direct access to Git uses code in GitLab known as the "Rugged patches".

History

Before Gitaly existed, what are now Gitaly clients used to access Git repositories directly, either:

On a local disk in the case of a single-machine Omnibus GitLab installation
Using NFS in the case of a horizontally-scaled GitLab installation.

Besides running plain git commands, GitLab used to use a Ruby library called Rugged. Rugged is a wrapper around libgit2, a stand-alone implementation of Git in the form of a C library.

Over time it became clear that Rugged, particularly in combination with Unicorn, is extremely efficient. Because libgit2 is a library and not an external process, there was very little overhead between:

GitLab application code that tried to look up data in Git repositories.
The Git implementation itself.

Because the combination of Rugged and Unicorn was so efficient, the GitLab application code ended up with lots of duplicate Git object lookups. For example, looking up the master commit a dozen times in one request. We could write inefficient code without poor performance.

When we migrated these Git lookups to Gitaly calls, we suddenly had a much higher fixed cost per Git lookup. Even when Gitaly is able to re-use an already-running git process (for example, to look up a commit), you still have:

The cost of a network roundtrip to Gitaly.
Within Gitaly, a write/read roundtrip on the Unix pipes that connect Gitaly to the git process.

Using GitLab.com to measure, we reduced the number of Gitaly calls per request until the loss of Rugged's efficiency was no longer felt. It also helped that we run Gitaly itself directly on the Git file severs, rather than via NFS mounts. This gave us a speed boost that counteracted the negative effect of not using Rugged anymore.

Unfortunately, other deployments of GitLab could not remove NFS like we did on GitLab.com, and they got the worst of both worlds:

The slowness of NFS.
The increased inherent overhead of Gitaly.

The code removed from GitLab during the Gitaly migration project affected these deployments. As a performance workaround for these NFS-based deployments, we re-introduced some of the old Rugged code. This re-introduced code is informally referred to as the "Rugged patches".

How it works

The Ruby methods that perform direct Git access are behind feature flags, disabled by default. It wasn't convenient to set feature flags to get the best performance, so we added an automatic mechanism that enables direct Git access.

When GitLab calls a function that has a "Rugged patch", it performs two checks:

Is the feature flag for this patch set in the database? If so, the feature flag setting controls the GitLab use of "Rugged patch" code.
If the feature flag is not set, GitLab tries accessing the file system underneath the Gitaly server directly. If it can, it uses the "Rugged patch":
- If using Unicorn.
- If using Puma and thread count is set to 1.

The result of these checks is cached.

To see if GitLab can access the repository file system directly, we use the following heuristic:

Gitaly ensures that the file system has a metadata file in its root with a UUID in it.
Gitaly reports this UUID to GitLab via the ServerInfo RPC.
GitLab Rails tries to read the metadata file directly. If it exists, and if the UUID's match, assume we have direct access.

Direct Git access is enable by default in Omnibus GitLab because it fills in the correct repository paths in the GitLab configuration file config/gitlab.yml. This satisfies the UUID check.

Transition to Gitaly Cluster

For the sake of removing complexity, we must remove direct Git access in GitLab. However, we can't remove it as long some GitLab installations require Git repositories on NFS.

There are two facets to our efforts to remove direct Git access in GitLab:

Reduce the number of inefficient Gitaly queries made by GitLab.
Persuade administrators of fault-tolerant or horizontally-scaled GitLab instances to migrate off NFS.

The second facet presents the only real solution. For this, we developed Gitaly Cluster.

Troubleshooting Gitaly

Check Gitaly timeouts when troubleshooting Gitaly.

Check versions when using standalone Gitaly servers

When using standalone Gitaly servers, you must make sure they are the same version as GitLab to ensure full compatibility. Check Admin Area > Overview > Gitaly Servers on your GitLab instance and confirm all Gitaly servers indicate that they are up to date.

`gitaly-debug`

The gitaly-debug command provides "production debugging" tools for Gitaly and Git performance. It is intended to help production engineers and support engineers investigate Gitaly performance problems.

If you're using GitLab 11.6 or newer, this tool should be installed on your GitLab / Gitaly server already at /opt/gitlab/embedded/bin/gitaly-debug. If you're investigating an older GitLab version you can compile this tool offline and copy the executable to your server:

git clone https://gitlab.com/gitlab-org/gitaly.git
cd cmd/gitaly-debug
GOOS=linux GOARCH=amd64 go build -o gitaly-debug

To see the help page of gitaly-debug for a list of supported sub-commands, run:

gitaly-debug -h

Commits, pushes, and clones return a 401

remote: GitLab: 401 Unauthorized

You need to sync your gitlab-secrets.json file with your Gitaly clients (GitLab app nodes).

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.

You can run a gRPC trace with:

sudo GRPC_TRACE=all GRPC_VERBOSITY=DEBUG gitlab-rake gitlab:gitaly:check

Correlating Git processes with RPCs

Sometimes you need to find out which Gitaly RPC created a particular Git process.

One method for doing this is via DEBUG logging. However, this needs to be enabled ahead of time and the logs produced are quite verbose.

A lightweight method for doing this correlation is by inspecting the environment of the Git process (using its PID) and looking at the CORRELATION_ID variable:

PID=<Git process ID>
sudo cat /proc/$PID/environ | tr '\0' '\n' | grep ^CORRELATION_ID=

Please note that this method is not reliable for git cat-file processes because Gitaly internally pools and re-uses those across RPCs.

Observing `gitaly-ruby` traffic

gitaly-ruby is an internal implementation detail of Gitaly, so, there's 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 RPCs in gitaly-ruby by querying grpc_client_handled_total. Strictly speaking, this metric does not differentiate between gitaly-ruby and other RPCs, 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 RPCs are (most likely) internally implemented as calls to gitaly-ruby:

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

Repository changes fail with a `401 Unauthorized` error

If you're running Gitaly on its own server and notice that users can successfully clone and fetch repositories (via both SSH and HTTPS), but can't push to them or make changes to the repository in the web UI without getting a 401 Unauthorized message, then it's possible Gitaly is failing to authenticate with the Gitaly client due to having the wrong secrets file.

Confirm the following are all true:

When any user performs a git push to any repository on this Gitaly server, it fails with the following error (note the 401 Unauthorized):

remote: GitLab: 401 Unauthorized
To <REMOTE_URL>
! [remote rejected] branch-name -> branch-name (pre-receive hook declined)
error: failed to push some refs to '<REMOTE_URL>'

When any user adds or modifies a file from the repository using the GitLab UI, it immediately fails with a red 401 Unauthorized banner.
Creating a new project and initializing it with a README successfully creates the project but doesn't create the README.

When tailing the logs on a Gitaly client and reproducing the error, you get 401 errors when reaching the /api/v4/internal/allowed endpoint:

# api_json.log
{
  "time": "2019-07-18T00:30:14.967Z",
  "severity": "INFO",
  "duration": 0.57,
  "db": 0,
  "view": 0.57,
  "status": 401,
  "method": "POST",
  "path": "\/api\/v4\/internal\/allowed",
  "params": [
    {
      "key": "action",
      "value": "git-receive-pack"
    },
    {
      "key": "changes",
      "value": "REDACTED"
    },
    {
      "key": "gl_repository",
      "value": "REDACTED"
    },
    {
      "key": "project",
      "value": "\/path\/to\/project.git"
    },
    {
      "key": "protocol",
      "value": "web"
    },
    {
      "key": "env",
      "value": "{\"GIT_ALTERNATE_OBJECT_DIRECTORIES\":[],\"GIT_ALTERNATE_OBJECT_DIRECTORIES_RELATIVE\":[],\"GIT_OBJECT_DIRECTORY\":null,\"GIT_OBJECT_DIRECTORY_RELATIVE\":null}"
    },
    {
      "key": "user_id",
      "value": "2"
    },
    {
      "key": "secret_token",
      "value": "[FILTERED]"
    }
  ],
  "host": "gitlab.example.com",
  "ip": "REDACTED",
  "ua": "Ruby",
  "route": "\/api\/:version\/internal\/allowed",
  "queue_duration": 4.24,
  "gitaly_calls": 0,
  "gitaly_duration": 0,
  "correlation_id": "XPUZqTukaP3"
}

# nginx_access.log
[IP] - - [18/Jul/2019:00:30:14 +0000] "POST /api/v4/internal/allowed HTTP/1.1" 401 30 "" "Ruby"

To fix this problem, confirm that your gitlab-secrets.json file on the Gitaly server matches the one on Gitaly client. If it doesn't match, update the secrets file on the Gitaly server to match the Gitaly client, then reconfigure.

Command line tools cannot connect to Gitaly

If you are having trouble connecting to a Gitaly server with command line (CLI) tools, and certain actions result in a 14: Connect Failed error message, it means that gRPC cannot reach your Gitaly server.

Verify that you can reach Gitaly via TCP:

sudo gitlab-rake gitlab:tcp_check[GITALY_SERVER_IP,GITALY_LISTEN_PORT]

If the TCP connection fails, check your network settings and your firewall rules. If the TCP connection succeeds, your networking and firewall rules are correct.

If you use proxy servers in your command line environment, such as Bash, these can interfere with your gRPC traffic.

If you use Bash or a compatible command line environment, run the following commands to determine whether you have proxy servers configured:

echo $http_proxy
echo $https_proxy

If either of these variables have a value, your Gitaly CLI connections may be getting routed through a proxy which cannot connect to Gitaly.

To remove the proxy setting, run the following commands (depending on which variables had values):

unset http_proxy
unset https_proxy

Permission denied errors appearing in Gitaly logs when accessing repositories from a standalone Gitaly server

If this error occurs even though file permissions are correct, it's likely that the Gitaly server is experiencing clock drift.

Please ensure that the Gitaly clients and servers are synchronized and use an NTP time server to keep them synchronized if possible.

Praefect

Praefect is a router and transaction manager for Gitaly, and a required component for running a Gitaly Cluster. For more information see Gitaly Cluster.

Gitaly

Architecture

Configure Gitaly

Run Gitaly on its own server

Network architecture

Install Gitaly

Configure authentication

Configure Gitaly servers

Configure Gitaly clients

Mixed configuration

Disable Gitaly where not required (optional)

Enable TLS support

Observe type of Gitaly connections

gitaly-ruby

Configure number of gitaly-ruby workers

Limit RPC concurrency

Rotate Gitaly authentication token

Verify authentication monitoring

Enable "auth transitioning" mode

Update Gitaly authentication token

Ensure there are no authentication failures

Disable "auth transitioning" mode

Verify authentication is enforced

Direct Git access bypassing Gitaly

Direct access to Git in GitLab

History

How it works

Transition to Gitaly Cluster

Troubleshooting Gitaly

Check versions when using standalone Gitaly servers

gitaly-debug

Commits, pushes, and clones return a 401

Client side gRPC logs

Correlating Git processes with RPCs

Observing gitaly-ruby traffic

Repository changes fail with a 401 Unauthorized error

Command line tools cannot connect to Gitaly

Permission denied errors appearing in Gitaly logs when accessing repositories from a standalone Gitaly server

Praefect

`gitaly-ruby`

Configure number of `gitaly-ruby` workers

`gitaly-debug`

Observing `gitaly-ruby` traffic

Repository changes fail with a `401 Unauthorized` error