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GitLab

Workhorse configuration

For historical reasons, Workhorse uses:

  • Command line flags.
  • A configuration file.
  • Environment variables.

Add any new Workhorse configuration options into the configuration file.

CLI options

  gitlab-workhorse [OPTIONS]

Options:
  -apiCiLongPollingDuration duration
        Long polling duration for job requesting for runners (default 50ns)
  -apiLimit uint
        Number of API requests allowed at single time
  -apiQueueDuration duration
        Maximum queueing duration of requests (default 30s)
  -apiQueueLimit uint
        Number of API requests allowed to be queued
  -authBackend string
        Authentication/authorization backend (default "http://localhost:8080")
  -authSocket string
        Optional: Unix domain socket to dial authBackend at
  -cableBackend string
        ActionCable backend
  -cableSocket string
        Optional: Unix domain socket to dial cableBackend at
  -config string
        TOML file to load config from
  -developmentMode
        Allow the assets to be served from Rails app
  -documentRoot string
        Path to static files content (default "public")
  -listenAddr string
        Listen address for HTTP server (default "localhost:8181")
  -listenNetwork string
        Listen 'network' (tcp, tcp4, tcp6, unix) (default "tcp")
  -listenUmask int
        Umask for Unix socket
  -logFile string
        Log file location
  -logFormat string
        Log format to use defaults to text (text, json, structured, none) (default "text")
  -pprofListenAddr string
        pprof listening address, e.g. 'localhost:6060'
  -prometheusListenAddr string
        Prometheus listening address, e.g. 'localhost:9229'
  -propagateCorrelationID X-Request-ID
        Reuse existing Correlation-ID from the incoming request header X-Request-ID if present
  -proxyHeadersTimeout duration
        How long to wait for response headers when proxying the request (default 5m0s)
  -secretPath string
        File with secret key to authenticate with authBackend (default "./.gitlab_workhorse_secret")
  -version
        Print version and exit

The 'auth backend' refers to the GitLab Rails application. The name is a holdover from when GitLab Workhorse only handled git push and git pull over HTTP.

GitLab Workhorse can listen on either a TCP or a Unix domain socket. It can also open a second listening TCP listening socket with the Go net/http/pprof profiler server.

GitLab Workhorse can listen on Redis build and runner registration events if you pass a valid TOML configuration file through the -config flag. A regular setup it only requires the following (replacing the string with the actual socket)

Redis

GitLab Workhorse integrates with Redis to do long polling for CI build requests. To configure it:

  • Configure Redis settings in the TOML configuration file.
  • Control polling behavior for CI build requests with the -apiCiLongPollingDuration command-line flag.

You can enable Redis in the configuration file while leaving CI polling disabled. This configuration results in an idle Redis Pub/Sub connection. The opposite is not possible: CI long polling requires a correct Redis configuration.

For example, the [redis] section in the configuration file could contain:

[redis]
URL = "unix:///var/run/gitlab/redis.sock"
Password = "my_awesome_password"
Sentinel = [ "tcp://sentinel1:23456", "tcp://sentinel2:23456" ]
SentinelMaster = "mymaster"
  • URL - A string in the format unix://path/to/redis.sock or tcp://host:port.
  • Password - Required only if your Redis instance is password-protected.
  • Sentinel - Required if you use Sentinel.

If both Sentinel and URL are given, only Sentinel is used.

Optional fields:

[redis]
DB = 0
MaxIdle = 1
MaxActive = 1
  • DB - The database to connect to. Defaults to 0.
  • MaxIdle - How many idle connections can be in the Redis pool at once. Defaults to 1.
  • MaxActive - How many connections the pool can keep. Defaults to 1.

Relative URL support

If you mount GitLab at a relative URL, like example.com/gitlab), use this relative URL in the authBackend setting:

gitlab-workhorse -authBackend http://localhost:8080/gitlab

TLS support

A listener with TLS can be configured to be used for incoming requests. Paths to the files containing a certificate and matching private key for the server must be provided:

[[listeners]]
network = "tcp"
addr = "localhost:3443"
[listeners.tls]
  certificate = "/path/to/certificate"
  key = "/path/to/private/key"
  min_version = "tls1.2"
  max_version = "tls1.3"

The certificate file should contain the concatenation of the server's certificate, any intermediates, and the CA's certificate.

Metrics endpoints can be configured similarly:

[metrics_listener]
network = "tcp"
addr = "localhost:9229"
[metrics_listener.tls]
  certificate = "/path/to/certificate"
  key = "/path/to/private/key"
  min_version = "tls1.2"
  max_version = "tls1.3"

Interaction of authBackend and authSocket

The interaction between authBackend and authSocket can be confusing. If authSocket is set, it overrides the host portion of authBackend, but not the relative path.

In table form:

authBackend authSocket Workhorse connects to Rails relative URL
unset unset localhost:8080 /
http://localhost:3000 unset localhost:3000 /
http://localhost:3000/gitlab unset localhost:3000 /gitlab
unset /path/to/socket /path/to/socket /
http://localhost:3000 /path/to/socket /path/to/socket /
http://localhost:3000/gitlab /path/to/socket /path/to/socket /gitlab

The same applies to cableBackend and cableSocket.

Error tracking

GitLab-Workhorse supports remote error tracking with Sentry. To enable this feature, set the GITLAB_WORKHORSE_SENTRY_DSN environment variable. You can also set the GITLAB_WORKHORSE_SENTRY_ENVIRONMENT environment variable to use the Sentry environment feature to separate staging, production and development.

Omnibus GitLab (/etc/gitlab/gitlab.rb):

gitlab_workhorse['env'] = {
    'GITLAB_WORKHORSE_SENTRY_DSN' => 'https://foobar'
    'GITLAB_WORKHORSE_SENTRY_ENVIRONMENT' => 'production'
}

Source installations (/etc/default/gitlab):

export GITLAB_WORKHORSE_SENTRY_DSN='https://foobar'
export GITLAB_WORKHORSE_SENTRY_ENVIRONMENT='production'

Distributed tracing

Workhorse supports distributed tracing through LabKit using OpenTracing APIs.

By default, no tracing implementation is linked into the binary. You can link in different OpenTracing providers with build tags or build constraints by setting the BUILD_TAGS make variable.

For more details of the supported providers, refer to LabKit. For an example of Jaeger tracing support, include the tags: BUILD_TAGS="tracer_static tracer_static_jaeger" like this:

make BUILD_TAGS="tracer_static tracer_static_jaeger"

After you compile Workhorse with an OpenTracing provider, configure the tracing configuration with the GITLAB_TRACING environment variable, like this:

GITLAB_TRACING=opentracing://jaeger ./gitlab-workhorse

Propagate correlation IDs

When a user makes an HTTP request, such as creating a new project, the initial request is routed through Workhorse to another service, which may in turn, make other requests. To help trace the request as it flows across services, Workhorse generates a random value called a correlation ID. Workhorse sends this correlation ID via the X-Request-Id HTTP header.

Some GitLab services, such as GitLab Shell, generate their own correlation IDs. In addition, other services, such as Gitaly, make internal API calls that pass along a correlation ID from the original request. In either case, the correlation ID is also passed via the X-Request-Id HTTP header.

By default, Workhorse ignores this header and always generates a new correlation ID. This makes debugging harder and prevents distributed tracing from working properly, since the new correlation ID is completely unrelated to the original one.

Workhorse can be configured to propagate an incoming correlation ID via the -propagateCorrelationID command-line flag. It is highly recommended that this option be used with an IP allow list to ensure arbitrary values cannot be generated by untrusted clients.

An IP allow list is specified via the trusted_cidrs_for_propagation option in the Workhorse configuration file. Specify a list of CIDR blocks that can be trusted. For example:

trusted_cidrs_for_propagation = ["10.0.0.0/8", "127.0.0.1/32"]

NOTE: The -propagateCorrelationID flag must be used for the trusted_cidrs_for_propagation option to work.

Trusted proxies

If Workhorse is behind a reverse proxy such as NGINX, the trusted_cidrs_for_x_forwarded_for option is needed to specify which CIDR blocks can be used to trust to provide the originating IP address via the X-Forwarded-For HTTP header. For example:

trusted_cidrs_for_x_forwarded_for = ["10.0.0.0/8", "127.0.0.1/32"]

Continuous profiling

Workhorse supports continuous profiling through LabKit using Stackdriver Profiler. By default, the Stackdriver Profiler implementation is linked in the binary using build tags, though it's not required and can be skipped. For example:

make BUILD_TAGS=""

After you compile Workhorse with continuous profiling, set the profiler configuration with the GITLAB_CONTINUOUS_PROFILING environment variable. For example:

GITLAB_CONTINUOUS_PROFILING="stackdriver?service=workhorse&service_version=1.0.1&project_id=test-123 ./gitlab-workhorse"

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