--- stage: none group: unassigned info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments --- # GitLab architecture overview ## Software delivery There are two software distributions of GitLab: - The open source [Community Edition](https://gitlab.com/gitlab-org/gitlab-foss/) (CE). - The open core [Enterprise Edition](https://gitlab.com/gitlab-org/gitlab/) (EE). GitLab is available under [different subscriptions](https://about.gitlab.com/pricing/). New versions of GitLab are released from stable branches, and the `main` branch is used for bleeding-edge development. For more information, see the [GitLab release process](https://about.gitlab.com/handbook/engineering/releases/). Both distributions require additional components. These components are described in the [Component details](#components) section, and all have their own repositories. New versions of each dependent component are usually tags, but staying on the `main` branch of the GitLab codebase gives you the latest stable version of those components. New versions are generally released around the same time as GitLab releases, with the exception of informal security updates deemed critical. ## Components A typical install of GitLab is on GNU/Linux, but growing number of deployments also use the Kubernetes platform. The largest known GitLab instance is on GitLab.com, which is deployed using our [official GitLab Helm chart](https://docs.gitlab.com/charts/) and the [official Linux package](https://about.gitlab.com/install/). A typical installation uses NGINX or Apache as a web server to proxy through [GitLab Workhorse](https://gitlab.com/gitlab-org/gitlab/tree/master/workhorse) and into the [Puma](https://puma.io) application server. GitLab serves web pages and the [GitLab API](../api/rest/index.md) using the Puma application server. It uses Sidekiq as a job queue which, in turn, uses Redis as a non-persistent database backend for job information, metadata, and incoming jobs. By default, communication between Puma and Workhorse is via a Unix domain socket, but forwarding requests via TCP is also supported. Workhorse accesses the `gitlab/public` directory, bypassing the Puma application server to serve static pages, uploads (for example, avatar images or attachments), and pre-compiled assets. The GitLab application uses PostgreSQL for persistent database information (for example, users, permissions, issues, or other metadata). GitLab stores the bare Git repositories in the location defined in [the configuration file, `repositories:` section](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example). It also keeps default branch and hook information with the bare repository. When serving repositories over HTTP/HTTPS GitLab uses the GitLab API to resolve authorization and access and to serve Git objects. The add-on component GitLab Shell serves repositories over SSH. It manages the SSH keys within the location defined in [the configuration file, `GitLab Shell` section](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example). The file in that location should never be manually edited. GitLab Shell accesses the bare repositories through Gitaly to serve Git objects, and communicates with Redis to submit jobs to Sidekiq for GitLab to process. GitLab Shell queries the GitLab API to determine authorization and access. Gitaly executes Git operations from GitLab Shell and the GitLab web app, and provides an API to the GitLab web app to get attributes from Git (for example, title, branches, tags, or other metadata), and to get blobs (for example, diffs, commits, or files). You may also be interested in the [production architecture of GitLab.com](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/). ## Adapting existing and introducing new components There are fundamental differences in how the application behaves when it is installed on a traditional Linux machine compared to a containerized platform, such as Kubernetes. Compared to [our official installation methods](https://about.gitlab.com/install/), some of the notable differences are: - Official Linux packages can access files on the same file system with different services. [Shared files](shared_files.md) are not an option for the application running on the Kubernetes platform. - Official Linux packages by default have services that have access to the shared configuration and network. This is not the case for services running in Kubernetes, where services might be running in complete isolation, or only accessible through specific ports. In other words, the shared state between services needs to be carefully considered when architecting new features and adding new components. Services that need to have access to the same files, need to be able to exchange information through the appropriate APIs. Whenever possible, this should not be done with files. Since components written with the API-first philosophy in mind are compatible with both methods, all new features and services must be written to consider Kubernetes compatibility **first**. The simplest way to ensure this, is to add support for your feature or service to [the official GitLab Helm chart](https://docs.gitlab.com/charts/) or reach out to [the Distribution team](https://about.gitlab.com/handbook/engineering/development/enablement/systems/distribution/#how-to-work-with-distribution). Refer to the [process for adding new service components](adding_service_component.md) for more details. ### Simplified component overview This is a simplified architecture diagram that can be used to understand the GitLab architecture. A complete architecture diagram is available in our [component diagram](#component-diagram) below. ![Simplified Component Overview](img/architecture_simplified_v14_9.png) ### Component diagram ```mermaid %%{init: {"flowchart": { "useMaxWidth": false } }}%% graph LR %% Anchor items in the appropriate subgraph. %% Link them where the destination* is. subgraph Clients Browser((Browser)) Git((Git)) end %% External Components / Applications Geo{{GitLab Geo}} -- TCP 80, 443 --> HTTP Geo -- TCP 22 --> SSH Geo -- TCP 5432 --> PostgreSQL Runner{{GitLab Runner}} -- TCP 443 --> HTTP K8sAgent{{GitLab Agent}} -- TCP 443 --> HTTP %% GitLab Application Suite subgraph GitLab subgraph Ingress HTTP[[HTTP/HTTPS]] SSH[[SSH]] NGINX[NGINX] GitLabShell[GitLab Shell] %% inbound/internal Browser -- TCP 80,443 --> HTTP Git -- TCP 80,443 --> HTTP Git -- TCP 22 --> SSH HTTP -- TCP 80, 443 --> NGINX SSH -- TCP 22 --> GitLabShell end subgraph GitLab Services %% inbound from NGINX NGINX --> GitLabWorkhorse NGINX -- TCP 8090 --> GitLabPages NGINX -- TCP 8150 --> GitLabKas NGINX --> Registry %% inbound from GitLabShell GitLabShell --> GitLabWorkhorse %% services Puma["Puma (GitLab Rails)"] Puma <--> Registry GitLabWorkhorse[GitLab Workhorse] <--> Puma GitLabKas[GitLab Agent Server] --> GitLabWorkhorse GitLabPages[GitLab Pages] --> GitLabWorkhorse Mailroom Sidekiq end subgraph Integrated Services %% Mattermost Mattermost Mattermost ---> GitLabWorkhorse NGINX --> Mattermost %% Grafana Grafana NGINX --> Grafana end subgraph Metadata %% PostgreSQL PostgreSQL PostgreSQL --> Consul %% Consul and inbound Consul Puma ---> Consul Sidekiq ---> Consul Migrations --> PostgreSQL %% PgBouncer and inbound PgBouncer PgBouncer --> Consul PgBouncer --> PostgreSQL Sidekiq --> PgBouncer Puma --> PgBouncer end subgraph State %% Redis and inbound Redis Puma --> Redis Sidekiq --> Redis GitLabWorkhorse --> Redis Mailroom --> Redis GitLabKas --> Redis %% Sentinel and inbound Sentinel <--> Redis Puma --> Sentinel Sidekiq --> Sentinel GitLabWorkhorse --> Sentinel Mailroom --> Sentinel GitLabKas --> Sentinel end subgraph Git Repositories %% Gitaly / Praefect Praefect --> Gitaly GitLabKas --> Praefect GitLabShell --> Praefect GitLabWorkhorse --> Praefect Puma --> Praefect Sidekiq --> Praefect Praefect <--> PraefectPGSQL[PostgreSQL] %% Gitaly makes API calls %% Ordered here to ensure placement. Gitaly --> GitLabWorkhorse end subgraph Storage %% ObjectStorage and inbound traffic ObjectStorage["Object Storage"] Puma -- TCP 443 --> ObjectStorage Sidekiq -- TCP 443 --> ObjectStorage GitLabWorkhorse -- TCP 443 --> ObjectStorage Registry -- TCP 443 --> ObjectStorage GitLabPages -- TCP 443 --> ObjectStorage end subgraph Monitoring %% Prometheus Grafana -- TCP 9090 --> Prometheus[Prometheus] Prometheus -- TCP 80, 443 --> Puma RedisExporter[Redis Exporter] --> Redis Prometheus -- TCP 9121 --> RedisExporter PostgreSQLExporter[PostgreSQL Exporter] --> PostgreSQL PgBouncerExporter[PgBouncer Exporter] --> PgBouncer Prometheus -- TCP 9187 --> PostgreSQLExporter Prometheus -- TCP 9100 --> NodeExporter[Node Exporter] Prometheus -- TCP 9168 --> GitLabExporter[GitLab Exporter] Prometheus -- TCP 9127 --> PgBouncerExporter Prometheus --> Alertmanager GitLabExporter --> PostgreSQL GitLabExporter --> GitLabShell GitLabExporter --> Sidekiq %% Alertmanager Alertmanager -- TCP 25 --> SMTP end %% end subgraph GitLab end subgraph External subgraph External Services SMTP[SMTP Gateway] LDAP %% Outbound SMTP Sidekiq -- TCP 25 --> SMTP Puma -- TCP 25 --> SMTP Mailroom -- TCP 25 --> SMTP %% Outbound LDAP Puma -- TCP 369 --> LDAP Sidekiq -- TCP 369 --> LDAP %% Elasticsearch Elasticsearch Puma -- TCP 9200 --> Elasticsearch Sidekiq -- TCP 9200 --> Elasticsearch end subgraph External Monitoring %% Sentry Sidekiq -- TCP 80, 443 --> Sentry Puma -- TCP 80, 443 --> Sentry %% Jaeger Jaeger Sidekiq -- UDP 6831 --> Jaeger Puma -- UDP 6831 --> Jaeger Gitaly -- UDP 6831 --> Jaeger GitLabShell -- UDP 6831 --> Jaeger GitLabWorkhorse -- UDP 6831 --> Jaeger end %% end subgraph External end click Alertmanager "./architecture.html#alertmanager" click Praefect "./architecture.html#praefect" click Geo "./architecture.html#gitlab-geo" click NGINX "./architecture.html#nginx" click Runner "./architecture.html#gitlab-runner" click Registry "./architecture.html#registry" click ObjectStorage "./architecture.html#minio" click Mattermost "./architecture.html#mattermost" click Gitaly "./architecture.html#gitaly" click Jaeger "./architecture.html#jaeger" click GitLabWorkhorse "./architecture.html#gitlab-workhorse" click LDAP "./architecture.html#ldap-authentication" click Puma "./architecture.html#puma" click GitLabShell "./architecture.html#gitlab-shell" click SSH "./architecture.html#ssh-request-22" click Sidekiq "./architecture.html#sidekiq" click Sentry "./architecture.html#sentry" click GitLabExporter "./architecture.html#gitlab-exporter" click Elasticsearch "./architecture.html#elasticsearch" click Migrations "./architecture.html#database-migrations" click PostgreSQL "./architecture.html#postgresql" click Consul "./architecture.html#consul" click PgBouncer "./architecture.html#pgbouncer" click PgBouncerExporter "./architecture.html#pgbouncer-exporter" click RedisExporter "./architecture.html#redis-exporter" click Redis "./architecture.html#redis" click Prometheus "./architecture.html#prometheus" click Grafana "./architecture.html#grafana" click GitLabPages "./architecture.html#gitlab-pages" click PostgreSQLExporter "./architecture.html#postgresql-exporter" click SMTP "./architecture.html#outbound-email" click NodeExporter "./architecture.html#node-exporter" ``` ### Component legend - ✅ - Installed by default - ⚙ - Requires additional configuration - ⤓ - Manual installation required - ❌ - Not supported or no instructions available - N/A - Not applicable Component statuses are linked to configuration documentation for each component. ### Component list | Component | Description | [Omnibus GitLab](https://docs.gitlab.com/omnibus/) | [GitLab Environment Toolkit (GET)](https://gitlab.com/gitlab-org/gitlab-environment-toolkit) | [GitLab chart](https://docs.gitlab.com/charts/) | [minikube Minimal](https://docs.gitlab.com/charts/development/minikube/#deploying-gitlab-with-minimal-settings) | [GitLab.com](https://gitlab.com) | [Source](../install/installation.md) | [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit) | [CE/EE](https://about.gitlab.com/install/ce-or-ee/) | |-------------------------------------------------------|----------------------------------------------------------------------|:--------------:|:--------------:|:------------:|:----------------:|:----------:|:------:|:---:|:-------:| | [Certificate Management](#certificate-management) | TLS Settings, Let's Encrypt | ✅ | ✅ | ✅ | ⚙ | ✅ | ⚙ | ⚙ | CE & EE | | [Consul](#consul) | Database node discovery, failover | ⚙ | ✅ | ❌ | ❌ | ✅ | ❌ | ❌ | EE Only | | [Database Migrations](#database-migrations) | Database migrations | ✅ | ✅ | ✅ | ✅ | ✅ | ⚙ | ✅ | CE & EE | | [Elasticsearch](#elasticsearch) | Improved search within GitLab | ⤓ | ⚙ | ⤓ | ⤓ | ✅ | ⤓ | ⚙ | EE Only | | [Gitaly](#gitaly) | Git RPC service for handling all Git calls made by GitLab | ✅ | ✅ | ✅ | ✅ | ✅ | ⚙ | ✅ | CE & EE | | [GitLab Exporter](#gitlab-exporter) | Generates a variety of GitLab metrics | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | CE & EE | | [GitLab Geo](#gitlab-geo) | Geographically distributed GitLab site | ⚙ | ⚙ | ❌ | ❌ | ✅ | ❌ | ⚙ | EE Only | | [GitLab Pages](#gitlab-pages) | Hosts static websites | ⚙ | ⚙ | ❌ | ❌ | ✅ | ⚙ | ⚙ | CE & EE | | [GitLab agent](#gitlab-agent) | Integrate Kubernetes clusters in a cloud-native way | ⚙ | ⚙ | ⚙ | ❌ | ❌ | ⤓ | ⚙ | EE Only | | [GitLab self-monitoring: Alertmanager](#alertmanager) | Deduplicates, groups, and routes alerts from Prometheus | ⚙ | ⚙ | ✅ | ⚙ | ✅ | ❌ | ❌ | CE & EE | | [GitLab self-monitoring: Grafana](#grafana) | Metrics dashboard | ✅ | ✅ | ⚙ | ⤓ | ✅ | ❌ | ⚙ | CE & EE | | [GitLab self-monitoring: Jaeger](#jaeger) | View traces generated by the GitLab instance | ❌ | ⚙ | ⚙ | ❌ | ❌ | ⤓ | ⚙ | CE & EE | | [GitLab self-monitoring: Prometheus](#prometheus) | Time-series database, metrics collection, and query service | ✅ | ✅ | ✅ | ⚙ | ✅ | ❌ | ⚙ | CE & EE | | [GitLab self-monitoring: Sentry](#sentry) | Track errors generated by the GitLab instance | ⤓ | ⤓ | ⤓ | ❌ | ✅ | ⤓ | ⤓ | CE & EE | | [GitLab Shell](#gitlab-shell) | Handles `git` over SSH sessions | ✅ | ✅ | ✅ | ✅ | ✅ | ⚙ | ✅ | CE & EE | | [GitLab Workhorse](#gitlab-workhorse) | Smart reverse proxy, handles large HTTP requests | ✅ | ✅ | ✅ | ✅ | ✅ | ⚙ | ✅ | CE & EE | | [Inbound email (SMTP)](#inbound-email) | Receive messages to update issues | ⤓ | ⤓ | ⚙ | ⤓ | ✅ | ⤓ | ⤓ | CE & EE | | [Jaeger integration](#jaeger) | Distributed tracing for deployed apps | ⤓ | ⤓ | ⤓ | ⤓ | ⤓ | ⤓ | ⚙ | EE Only | | [LDAP Authentication](#ldap-authentication) | Authenticate users against centralized LDAP directory | ⤓ | ⤓ | ⤓ | ⤓ | ❌ | ⤓ | ⚙ | CE & EE | | [Mattermost](#mattermost) | Open-source Slack alternative | ⚙ | ⚙ | ⤓ | ⤓ | ⤓ | ❌ | ⚙ | CE & EE | | [MinIO](#minio) | Object storage service | ⤓ | ⤓ | ✅ | ✅ | ✅ | ❌ | ⚙ | CE & EE | | [NGINX](#nginx) | Routes requests to appropriate components, terminates SSL | ✅ | ✅ | ✅ | ⚙ | ✅ | ⤓ | ⚙ | CE & EE | | [Node Exporter](#node-exporter) | Prometheus endpoint with system metrics | ✅ | ✅ | N/A | N/A | ✅ | ❌ | ❌ | CE & EE | | [Outbound email (SMTP)](#outbound-email) | Send email messages to users | ⤓ | ⤓ | ⚙ | ⤓ | ✅ | ⤓ | ⤓ | CE & EE | | [Patroni](#patroni) | Manage PostgreSQL HA cluster leader selection and replication | ⚙ | ✅ | ❌ | ❌ | ✅ | ❌ | ❌ | EE Only | | [PgBouncer Exporter](#pgbouncer-exporter) | Prometheus endpoint with PgBouncer metrics | ⚙ | ✅ | ❌ | ❌ | ✅ | ❌ | ❌ | CE & EE | | [PgBouncer](#pgbouncer) | Database connection pooling, failover | ⚙ | ✅ | ❌ | ❌ | ✅ | ❌ | ❌ | EE Only | | [PostgreSQL Exporter](#postgresql-exporter) | Prometheus endpoint with PostgreSQL metrics | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | CE & EE | | [PostgreSQL](#postgresql) | Database | ✅ | ✅ | ✅ | ✅ | ✅ | ⤓ | ✅ | CE & EE | | [Praefect](#praefect) | A transparent proxy between any Git client and Gitaly storage nodes. | ✅ | ✅ | ⚙ | ❌ | ✅ | ⚙ | ✅ | CE & EE | | [Puma (GitLab Rails)](#puma) | Handles requests for the web interface and API | ✅ | ✅ | ✅ | ✅ | ✅ | ⚙ | ✅ | CE & EE | | [Redis Exporter](#redis-exporter) | Prometheus endpoint with Redis metrics | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | CE & EE | | [Redis](#redis) | Caching service | ✅ | ✅ | ✅ | ✅ | ✅ | ⤓ | ✅ | CE & EE | | [Registry](#registry) | Container registry, allows pushing and pulling of images | ⚙ | ⚙ | ✅ | ✅ | ✅ | ⤓ | ⚙ | CE & EE | | [Runner](#gitlab-runner) | Executes GitLab CI/CD jobs | ⤓ | ⤓ | ✅ | ⚙ | ✅ | ⚙ | ⚙ | CE & EE | | [Sentry integration](#sentry) | Error tracking for deployed apps | ⤓ | ⤓ | ⤓ | ⤓ | ⤓ | ⤓ | ⤓ | CE & EE | | [Sidekiq](#sidekiq) | Background jobs processor | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | CE & EE | | [Token Revocation API](sec/token_revocation_api.md) | Receives and revokes leaked secrets | ❌ | ❌ | ❌ | ❌ | ✅ | ❌ | ❌ | EE Only | ### Component details This document is designed to be consumed by systems administrators and GitLab Support Engineers who want to understand more about the internals of GitLab and how they work together. When deployed, GitLab should be considered the amalgamation of the below processes. When troubleshooting or debugging, be as specific as possible as to which component you are referencing. That should increase clarity and reduce confusion. **Layers** GitLab can be considered to have two layers from a process perspective: - **Monitoring**: Anything from this layer is not required to deliver GitLab the application, but allows administrators more insight into their infrastructure and what the service as a whole is doing. - **Core**: Any process that is vital for the delivery of GitLab as a platform. If any of these processes halt, a GitLab outage results. For the Core layer, you can further divide into: - **Processors**: These processes are responsible for actually performing operations and presenting the service. - **Data**: These services store/expose structured data for the GitLab service. #### Alertmanager - [Project page](https://github.com/prometheus/alertmanager/blob/master/README.md) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template) - [Charts](https://github.com/helm/charts/tree/master/stable/prometheus) - Layer: Monitoring - Process: `alertmanager` - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) [Alert manager](https://prometheus.io/docs/alerting/latest/alertmanager/) is a tool provided by Prometheus that _"handles alerts sent by client applications such as the Prometheus server. It takes care of deduplicating, grouping, and routing them to the correct receiver integration such as email, PagerDuty, or Opsgenie. It also takes care of silencing and inhibition of alerts."_ You can read more in [issue #45740](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/45740) about what we alert on. #### Certificate management - Project page: - [Omnibus](https://github.com/certbot/certbot/blob/master/README.rst) - [Charts](https://github.com/jetstack/cert-manager/blob/master/README.md) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/ssl.html) - [Charts](https://docs.gitlab.com/charts/installation/tls.html) - [Source](../install/installation.md#using-https) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/https.md) - Layer: Core Service (Processor) - GitLab.com: [Secrets Management](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#secrets-management) #### Consul - [Project page](https://github.com/hashicorp/consul/blob/master/README.md) - Configuration: - [Omnibus](../administration/consul.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#postgresql) - Layer: Core Service (Data) - GitLab.com: [Consul](../user/gitlab_com/index.md#consul) Consul is a tool for service discovery and configuration. Consul is distributed, highly available, and extremely scalable. #### Database migrations - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/database.html#disabling-automatic-database-migration) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/migrations/) - [Source](../update/upgrading_from_source.md#10-install-libraries-migrations-etc) - Layer: Core Service (Data) #### Elasticsearch - [Project page](https://github.com/elastic/elasticsearch/) - Configuration: - [Omnibus](../integration/advanced_search/elasticsearch.md) - [Charts](../integration/advanced_search/elasticsearch.md) - [Source](../integration/advanced_search/elasticsearch.md) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/elasticsearch.md) - Layer: Core Service (Data) - GitLab.com: [Get Advanced Search working on GitLab.com (Closed)](https://gitlab.com/groups/gitlab-org/-/epics/153) epic. Elasticsearch is a distributed RESTful search engine built for the cloud. #### Gitaly - [Project page](https://gitlab.com/gitlab-org/gitaly/blob/master/README.md) - Configuration: - [Omnibus](../administration/gitaly/index.md) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/gitaly/) - [Source](../install/installation.md#install-gitaly) - Layer: Core Service (Data) - Process: `gitaly` - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) Gitaly is a service designed by GitLab to remove our need for NFS for Git storage in distributed deployments of GitLab (think GitLab.com or High Availability Deployments). As of 11.3.0, this service handles all Git level access in GitLab. You can read more about the project [in the project's README](https://gitlab.com/gitlab-org/gitaly). #### Praefect - [Project page](https://gitlab.com/gitlab-org/gitaly/blob/master/README.md) - Configuration: - [Omnibus](../administration/gitaly/index.md) - [Source](../install/installation.md#install-gitaly) - Layer: Core Service (Data) - Process: `praefect` - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) Praefect is a transparent proxy between each Git client and the Gitaly coordinating the replication of repository updates to secondary nodes. #### GitLab Geo - Configuration: - [Omnibus](../administration/geo/setup/index.md) - [Charts](https://docs.gitlab.com/charts/advanced/geo/) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/geo.md) - Layer: Core Service (Processor) Geo is a premium feature built to help speed up the development of distributed teams by providing one or more read-only mirrors of a primary GitLab instance. This mirror (a Geo secondary site) reduces the time to clone or fetch large repositories and projects, or can be part of a Disaster Recovery solution. #### GitLab Exporter - [Project page](https://gitlab.com/gitlab-org/gitlab-exporter) - Configuration: - [Omnibus](../administration/monitoring/prometheus/gitlab_exporter.md) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/gitlab-exporter/index.html) - Layer: Monitoring - Process: `gitlab-exporter` - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) GitLab Exporter is a process designed in house that allows us to export metrics about GitLab application internals to Prometheus. You can read more [in the project's README](https://gitlab.com/gitlab-org/gitlab-exporter). #### GitLab agent - [Project page](https://gitlab.com/gitlab-org/cluster-integration/gitlab-agent) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/kas/index.html) The [GitLab agent](../user/clusters/agent/index.md) is an active in-cluster component for solving GitLab and Kubernetes integration tasks in a secure and cloud-native way. You can use it to sync deployments onto your Kubernetes cluster. #### GitLab Pages - Configuration: - [Omnibus](../administration/pages/index.md) - [Charts](https://gitlab.com/gitlab-org/charts/gitlab/-/issues/37) - [Source](../install/installation.md#install-gitlab-pages) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/pages.md) - Layer: Core Service (Processor) - GitLab.com: [GitLab Pages](../user/gitlab_com/index.md#gitlab-pages) GitLab Pages is a feature that allows you to publish static websites directly from a repository in GitLab. You can use it either for personal or business websites, such as portfolios, documentation, manifestos, and business presentations. You can also attribute any license to your content. #### GitLab Runner - [Project page](https://gitlab.com/gitlab-org/gitlab-runner/blob/main/README.md) - Configuration: - [Omnibus](https://docs.gitlab.com/runner/) - [Charts](https://docs.gitlab.com/runner/install/kubernetes.html) - [Source](https://docs.gitlab.com/runner/) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/runner.md) - Layer: Core Service (Processor) - GitLab.com: [Runners](../ci/runners/index.md) GitLab Runner runs jobs and sends the results to GitLab. GitLab CI/CD is the open-source continuous integration service included with GitLab that coordinates the testing. The old name of this project was `GitLab CI Multi Runner` but please use `GitLab Runner` (without CI) from now on. #### GitLab Shell - [Project page](https://gitlab.com/gitlab-org/gitlab-shell/) - [Documentation](gitlab_shell/index.md) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/gitlab-shell/) - [Source](../install/installation.md#install-gitlab-shell) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Core Service (Processor) - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) [GitLab Shell](gitlab_shell/index.md) is a program designed at GitLab to handle SSH-based `git` sessions, and modifies the list of authorized keys. GitLab Shell is not a Unix shell nor a replacement for Bash or Zsh. #### GitLab Workhorse - [Project page](https://gitlab.com/gitlab-org/gitlab-workhorse/blob/master/README.md) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/webservice/) - [Source](../install/installation.md#install-gitlab-workhorse) - Layer: Core Service (Processor) - Process: `gitlab-workhorse` - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) [GitLab Workhorse](https://gitlab.com/gitlab-org/gitlab-workhorse) is a program designed at GitLab to help alleviate pressure from Puma. You can read more about the [historical reasons for developing](https://about.gitlab.com/blog/2016/04/12/a-brief-history-of-gitlab-workhorse/). It's designed to act as a smart reverse proxy to help speed up GitLab as a whole. #### Grafana - [Project page](https://github.com/grafana/grafana/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/performance/grafana_configuration.md) - [Charts](https://docs.gitlab.com/charts/charts/globals#configure-grafana-integration) - Layer: Monitoring - GitLab.com: [GitLab triage Grafana dashboard](https://dashboards.gitlab.com/d/RZmbBr7mk/gitlab-triage?refresh=30s) Grafana is an open source, feature rich metrics dashboard and graph editor for Graphite, Elasticsearch, OpenTSDB, Prometheus, and InfluxDB. #### Jaeger - [Project page](https://github.com/jaegertracing/jaeger/blob/master/README.md) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/4104) - [Charts](https://docs.gitlab.com/charts/charts/globals#tracing) - [Source](../development/distributed_tracing.md#enabling-distributed-tracing) - [GDK](../development/distributed_tracing.md#using-jaeger-in-the-gitlab-development-kit) - Layer: Monitoring - GitLab.com: [Configuration to enable Tracing for a GitLab instance](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/4104) issue. Jaeger, inspired by Dapper and OpenZipkin, is a distributed tracing system. It can be used for monitoring microservices-based distributed systems. #### Logrotate - [Project page](https://github.com/logrotate/logrotate/blob/master/README.md) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/logs.html#logrotate) - Layer: Core Service - Process: `logrotate` GitLab is comprised of a large number of services that all log. We bundle our own Logrotate to make sure we were logging responsibly. This is just a packaged version of the common open source offering. #### Mattermost - [Project page](https://github.com/mattermost/mattermost-server/blob/master/README.md) - Configuration: - [Omnibus](../integration/mattermost/index.md) - [Charts](https://docs.mattermost.com/install/install-mmte-helm-gitlab-helm.html) - Layer: Core Service (Processor) - GitLab.com: [Mattermost](../user/project/integrations/mattermost.md) Mattermost is an open source, private cloud, Slack-alternative from . #### MinIO - [Project page](https://github.com/minio/minio/blob/master/README.md) - Configuration: - [Omnibus](https://min.io/download) - [Charts](https://docs.gitlab.com/charts/charts/minio/) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/object_storage.md) - Layer: Core Service (Data) - GitLab.com: [Storage Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#storage-architecture) MinIO is an object storage server released under the GNU AGPL v3.0. It is compatible with Amazon S3 cloud storage service. It is best suited for storing unstructured data such as photos, videos, log files, backups, and container / VM images. Size of an object can range from a few KB to a maximum of 5 TB. #### NGINX - Project page: - [Omnibus](https://github.com/nginx/nginx) - [Charts](https://github.com/kubernetes/ingress-nginx/blob/master/README.md) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/) - [Charts](https://docs.gitlab.com/charts/charts/nginx/) - [Source](../install/installation.md#9-nginx) - Layer: Core Service (Processor) - Process: `nginx` - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) NGINX has an Ingress port for all HTTP requests and routes them to the appropriate sub-systems within GitLab. We are bundling an unmodified version of the popular open source webserver. #### Node Exporter - [Project page](https://github.com/prometheus/node_exporter/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/prometheus/node_exporter.md) - [Charts](https://gitlab.com/gitlab-org/charts/gitlab/-/issues/1332) - Layer: Monitoring - Process: `node-exporter` - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) [Node Exporter](https://github.com/prometheus/node_exporter) is a Prometheus tool that gives us metrics on the underlying machine (think CPU/Disk/Load). It's just a packaged version of the common open source offering from the Prometheus project. #### Patroni - [Project Page](https://github.com/zalando/patroni) - Configuration: - [Omnibus](../administration/postgresql/replication_and_failover.md#patroni) - Layer: Core Service (Data) - Process: `patroni` - GitLab.com: [Database Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#database-architecture) #### PgBouncer - [Project page](https://github.com/pgbouncer/pgbouncer/blob/master/README.md) - Configuration: - [Omnibus](../administration/postgresql/pgbouncer.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#postgresql) - Layer: Core Service (Data) - GitLab.com: [Database Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#database-architecture) Lightweight connection pooler for PostgreSQL. #### PgBouncer Exporter - [Project page](https://github.com/prometheus-community/pgbouncer_exporter/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/prometheus/pgbouncer_exporter.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#postgresql) - Layer: Monitoring - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) Prometheus exporter for PgBouncer. Exports metrics at 9127/metrics. #### PostgreSQL - [Project page](https://github.com/postgres/postgres/blob/master/README) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/database.html) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#postgresql) - [Source](../install/installation.md#6-database) - Layer: Core Service (Data) - Process: `postgresql` - GitLab.com: [PostgreSQL](../user/gitlab_com/index.md#postgresql) GitLab packages the popular Database to provide storage for Application meta data and user information. #### PostgreSQL Exporter - [Project page](https://github.com/wrouesnel/postgres_exporter/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/prometheus/postgres_exporter.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#postgresql) - Layer: Monitoring - Process: `postgres-exporter` - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) [`postgres_exporter`](https://github.com/wrouesnel/postgres_exporter) is the community provided Prometheus exporter that delivers data about PostgreSQL to Prometheus for use in Grafana Dashboards. #### Prometheus - [Project page](https://github.com/prometheus/prometheus/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/prometheus/index.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#prometheus) - Layer: Monitoring - Process: `prometheus` - GitLab.com: [Prometheus](../user/gitlab_com/index.md#prometheus) Prometheus is a time-series tool that helps GitLab administrators expose metrics about the individual processes used to provide GitLab the service. #### Redis - [Project page](https://github.com/antirez/redis/blob/unstable/README.md) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/redis.html) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#redis) - [Source](../install/installation.md#7-redis) - Layer: Core Service (Data) - Process: `redis` - GitLab.com: [Service Architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/#service-architecture) Redis is packaged to provide a place to store: - session data - temporary cache information - background job queues See our [Redis guidelines](redis.md) for more information about how GitLab uses Redis. #### Redis Exporter - [Project page](https://github.com/oliver006/redis_exporter/blob/master/README.md) - Configuration: - [Omnibus](../administration/monitoring/prometheus/redis_exporter.md) - [Charts](https://docs.gitlab.com/charts/installation/deployment.html#redis) - Layer: Monitoring - Process: `redis-exporter` - GitLab.com: [Monitoring of GitLab.com](https://about.gitlab.com/handbook/engineering/monitoring/) [Redis Exporter](https://github.com/oliver006/redis_exporter) is designed to give specific metrics about the Redis process to Prometheus so that we can graph these metrics in Grafana. #### Registry - [Project page](https://github.com/docker/distribution/blob/master/README.md) - Configuration: - [Omnibus](../update/upgrading_from_source.md#10-install-libraries-migrations-etc) - [Charts](https://docs.gitlab.com/charts/charts/registry/) - [Source](../administration/packages/container_registry.md#enable-the-container-registry) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/registry.md) - Layer: Core Service (Processor) - GitLab.com: [GitLab Container Registry](../user/packages/container_registry/build_and_push_images.md#use-gitlab-cicd) The registry is what users use to store their own Docker images. The bundled registry uses NGINX as a load balancer and GitLab as an authentication manager. Whenever a client requests to pull or push an image from the registry, it returns a `401` response along with a header detailing where to get an authentication token, in this case the GitLab instance. The client then requests a pull or push auth token from GitLab and retries the original request to the registry. For more information, see [token authentication](https://docs.docker.com/registry/spec/auth/token/). An external registry can also be configured to use GitLab as an auth endpoint. #### Sentry - [Project page](https://github.com/getsentry/sentry/) - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/configuration.html#error-reporting-and-logging-with-sentry) - [Charts](https://docs.gitlab.com/charts/charts/globals#sentry-settings) - [Source](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Monitoring - GitLab.com: [Searching Sentry](https://about.gitlab.com/handbook/support/workflows/500_errors.html#searching-sentry) Sentry fundamentally is a service that helps you monitor and fix crashes in real time. The server is in Python, but it contains a full API for sending events from any language, in any application. For monitoring deployed apps, see the [Sentry integration docs](../operations/error_tracking.md) #### Sidekiq - [Project page](https://github.com/mperham/sidekiq/blob/master/README.md) - Configuration: - [Omnibus](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/sidekiq/) - [minikube Minimal](https://docs.gitlab.com/charts/charts/gitlab/sidekiq/index.html) - [Source](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Core Service (Processor) - Process: `sidekiq` - GitLab.com: [Sidekiq](../user/gitlab_com/index.md#sidekiq) Sidekiq is a Ruby background job processor that pulls jobs from the Redis queue and processes them. Background jobs allow GitLab to provide a faster request/response cycle by moving work into the background. #### Puma Starting with GitLab 13.0, Puma is the default web server. - [Project page](https://gitlab.com/gitlab-org/gitlab/-/blob/master/README.md) - Configuration: - [Omnibus](../administration/operations/puma.md) - [Charts](https://docs.gitlab.com/charts/charts/gitlab/webservice/) - [Source](../install/installation.md#configure-it) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Core Service (Processor) - Process: `puma` - GitLab.com: [Puma](../user/gitlab_com/index.md#puma) [Puma](https://puma.io/) is a Ruby application server that is used to run the core Rails Application that provides the user facing features in GitLab. Often this displays in process output as `bundle` or `config.ru` depending on the GitLab version. #### LDAP Authentication - Configuration: - [Omnibus](../administration/auth/ldap/index.md) - [Charts](https://docs.gitlab.com/charts/charts/globals.html#ldap) - [Source](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - [GDK](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/ldap.md) - Layer: Core Service (Processor) - GitLab.com: [Product Tiers](https://about.gitlab.com/pricing/#gitlab-com) #### Outbound Email - Configuration: - [Omnibus](https://docs.gitlab.com/omnibus/settings/smtp.html) - [Charts](https://docs.gitlab.com/charts/installation/command-line-options.html#outgoing-email-configuration) - [Source](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Core Service (Processor) - GitLab.com: [Mail configuration](../user/gitlab_com/index.md#mail-configuration) #### Inbound Email - Configuration: - [Omnibus](../administration/incoming_email.md) - [Charts](https://docs.gitlab.com/charts/installation/command-line-options.html#incoming-email-configuration) - [Source](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - [GDK](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/gitlab.yml.example) - Layer: Core Service (Processor) - GitLab.com: [Mail configuration](../user/gitlab_com/index.md#mail-configuration) ## GitLab by request type GitLab provides two "interfaces" for end users to access the service: - Web HTTP Requests (Viewing the UI/API) - Git HTTP/SSH Requests (Pushing/Pulling Git Data) It's important to understand the distinction as some processes are used in both and others are exclusive to a specific request type. ### GitLab Web HTTP request cycle When making a request to an HTTP Endpoint (think `/users/sign_in`) the request takes the following path through the GitLab Service: - NGINX - Acts as our first line reverse proxy. - GitLab Workhorse - This determines if it needs to go to the Rails application or somewhere else to reduce load on Puma. - Puma - Since this is a web request, and it needs to access the application, it routes to Puma. - PostgreSQL/Gitaly/Redis - Depending on the type of request, it may hit these services to store or retrieve data. ### GitLab Git request cycle Below we describe the different paths that HTTP vs. SSH Git requests take. There is some overlap with the Web Request Cycle but also some differences. ### Web request (80/443) Git operations over HTTP use the stateless "smart" protocol described in the [Git documentation](https://git-scm.com/docs/http-protocol), but responsibility for handling these operations is split across several GitLab components. Here is a sequence diagram for `git fetch`. Note that all requests pass through NGINX as well as any other HTTP load balancers, but are not transformed in any way by them. All paths are presented relative to a `/namespace/project.git` URL. ```mermaid sequenceDiagram participant Git on client participant NGINX participant Workhorse participant Rails participant Gitaly participant Git on server Note left of Git on client: git fetch
info-refs Git on client->>+Workhorse: GET /info/refs?service=git-upload-pack Workhorse->>+Rails: GET /info/refs?service=git-upload-pack Note right of Rails: Auth check Rails-->>-Workhorse: Gitlab::Workhorse.git_http_ok Workhorse->>+Gitaly: SmartHTTPService.InfoRefsUploadPack request Gitaly->>+Git on server: git upload-pack --stateless-rpc --advertise-refs Git on server-->>-Gitaly: git upload-pack response Gitaly-->>-Workhorse: SmartHTTPService.InfoRefsUploadPack response Workhorse-->>-Git on client: 200 OK Note left of Git on client: git fetch
fetch-pack Git on client->>+Workhorse: POST /git-upload-pack Workhorse->>+Rails: POST /git-upload-pack Note right of Rails: Auth check Rails-->>-Workhorse: Gitlab::Workhorse.git_http_ok Workhorse->>+Gitaly: SmartHTTPService.PostUploadPack request Gitaly->>+Git on server: git upload-pack --stateless-rpc Git on server-->>-Gitaly: git upload-pack response Gitaly-->>-Workhorse: SmartHTTPService.PostUploadPack response Workhorse-->>-Git on client: 200 OK ``` The sequence is similar for `git push`, except `git-receive-pack` is used instead of `git-upload-pack`. ### SSH request (22) Git operations over SSH can use the stateful protocol described in the [Git documentation](https://git-scm.com/docs/pack-protocol#_ssh_transport), but responsibility for handling them is split across several GitLab components. No GitLab components speak SSH directly - all SSH connections are made between Git on the client machine and the SSH server, which terminates the connection. To the SSH server, all connections are authenticated as the `git` user; GitLab users are differentiated by the SSH key presented by the client. Here is a sequence diagram for `git fetch`, assuming [Fast SSH key lookup](../administration/operations/fast_ssh_key_lookup.md) is enabled. Note that `AuthorizedKeysCommand` is an executable provided by [GitLab Shell](#gitlab-shell): ```mermaid sequenceDiagram participant Git on client participant SSH server participant AuthorizedKeysCommand participant GitLab Shell participant Rails participant Gitaly participant Git on server Note left of Git on client: git fetch Git on client->>+SSH server: ssh git fetch-pack request SSH server->>+AuthorizedKeysCommand: gitlab-shell-authorized-keys-check git AAAA... AuthorizedKeysCommand->>+Rails: GET /internal/api/authorized_keys?key=AAAA... Note right of Rails: Lookup key ID Rails-->>-AuthorizedKeysCommand: 200 OK, command="gitlab-shell upload-pack key_id=1" AuthorizedKeysCommand-->>-SSH server: command="gitlab-shell upload-pack key_id=1" SSH server->>+GitLab Shell: gitlab-shell upload-pack key_id=1 GitLab Shell->>+Rails: GET /internal/api/allowed?action=upload_pack&key_id=1 Note right of Rails: Auth check Rails-->>-GitLab Shell: 200 OK, { gitaly: ... } GitLab Shell->>+Gitaly: SSHService.SSHUploadPack request Gitaly->>+Git on server: git upload-pack request Note over Git on client,Git on server: Bidirectional communication between Git client and server Git on server-->>-Gitaly: git upload-pack response Gitaly -->>-GitLab Shell: SSHService.SSHUploadPack response GitLab Shell-->>-SSH server: gitlab-shell upload-pack response SSH server-->>-Git on client: ssh git fetch-pack response ``` The `git push` operation is very similar, except `git receive-pack` is used instead of `git upload-pack`. If fast SSH key lookups are not enabled, the SSH server reads from the `~git/.ssh/authorized_keys` file to determine what command to run for a given SSH session. This is kept up to date by an [`AuthorizedKeysWorker`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/workers/authorized_keys_worker.rb) in Rails, scheduled to run whenever an SSH key is modified by a user. [SSH certificates](../administration/operations/ssh_certificates.md) may be used instead of keys. In this case, `AuthorizedKeysCommand` is replaced with an `AuthorizedPrincipalsCommand`. This extracts a username from the certificate without using the Rails internal API, which is used instead of `key_id` in the [`/api/internal/allowed`](internal_api/index.md) call later. GitLab Shell also has a few operations that do not involve Gitaly, such as resetting two-factor authentication codes. These are handled in the same way, except there is no round-trip into Gitaly - Rails performs the action as part of the [internal API](internal_api/index.md) call, and GitLab Shell streams the response back to the user directly. ## System layout When referring to `~git` in the pictures it means the home directory of the Git user which is typically `/home/git`. GitLab is primarily installed within the `/home/git` user home directory as `git` user. Within the home directory is where the GitLab server software resides as well as the repositories (though the repository location is configurable). The bare repositories are located in `/home/git/repositories`. GitLab is a Ruby on rails application so the particulars of the inner workings can be learned by studying how a Ruby on rails application works. To serve repositories over SSH there's an add-on application called GitLab Shell which is installed in `/home/git/gitlab-shell`. ### Installation folder summary To summarize here's the [directory structure of the `git` user home directory](../install/installation.md#gitlab-directory-structure). ### Processes ```shell ps aux | grep '^git' ``` GitLab has several components to operate. It requires a persistent database (PostgreSQL) and Redis database, and uses Apache `httpd` or NGINX to `proxypass` Puma. All these components should run as different system users to GitLab (for example, `postgres`, `redis`, and `www-data`, instead of `git`). As the `git` user it starts Sidekiq and Puma (a simple Ruby HTTP server running on port `8080` by default). Under the GitLab user there are normally 4 processes: `puma master` (1 process), `puma cluster worker` (2 processes), `sidekiq` (1 process). ### Repository access Repositories get accessed via HTTP or SSH. HTTP cloning/push/pull uses the GitLab API and SSH cloning is handled by GitLab Shell (previously explained). ## Troubleshooting See the README for more information. ### Init scripts of the services The GitLab init script starts and stops Puma and Sidekiq: ```plaintext /etc/init.d/gitlab Usage: service gitlab {start|stop|restart|reload|status} ``` Redis (key-value store/non-persistent database): ```plaintext /etc/init.d/redis Usage: /etc/init.d/redis {start|stop|status|restart|condrestart|try-restart} ``` SSH daemon: ```plaintext /etc/init.d/sshd Usage: /etc/init.d/sshd {start|stop|restart|reload|force-reload|condrestart|try-restart|status} ``` Web server (one of the following): ```plaintext /etc/init.d/httpd Usage: httpd {start|stop|restart|condrestart|try-restart|force-reload|reload|status|fullstatus|graceful|help|configtest} $ /etc/init.d/nginx Usage: nginx {start|stop|restart|reload|force-reload|status|configtest} ``` Persistent database: ```plaintext $ /etc/init.d/postgresql Usage: /etc/init.d/postgresql {start|stop|restart|reload|force-reload|status} [version ..] ``` ### Log locations of the services GitLab (includes Puma and Sidekiq logs): - `/home/git/gitlab/log/` contains `application.log`, `production.log`, `sidekiq.log`, `puma.stdout.log`, `git_json.log` and `puma.stderr.log` normally. GitLab Shell: - `/home/git/gitlab-shell/gitlab-shell.log` SSH: - `/var/log/auth.log` auth log (on Ubuntu). - `/var/log/secure` auth log (on RHEL). NGINX: - `/var/log/nginx/` contains error and access logs. Apache `httpd`: - [Explanation of Apache logs](https://httpd.apache.org/docs/2.2/logs.html). - `/var/log/apache2/` contains error and output logs (on Ubuntu). - `/var/log/httpd/` contains error and output logs (on RHEL). Redis: - `/var/log/redis/redis.log` there are also log-rotated logs there. PostgreSQL: - `/var/log/postgresql/*` ### GitLab specific configuration files GitLab has configuration files located in `/home/git/gitlab/config/*`. Commonly referenced configuration files include: - `gitlab.yml`: GitLab configuration - `puma.rb`: Puma web server settings - `database.yml`: Database connection settings GitLab Shell has a configuration file at `/home/git/gitlab-shell/config.yml`. ### Maintenance tasks [GitLab](https://gitlab.com/gitlab-org/gitlab/-/tree/master) provides Rake tasks with which you see version information and run a quick check on your configuration to ensure it is configured properly within the application. See [maintenance Rake tasks](../administration/raketasks/maintenance.md). In a nutshell, do the following: ```shell sudo -i -u git cd gitlab bundle exec rake gitlab:env:info RAILS_ENV=production bundle exec rake gitlab:check RAILS_ENV=production ``` It's recommended to sign in to the `git` user using either `sudo -i -u git` or `sudo su - git`. Although the `sudo` commands provided by GitLab work in Ubuntu, they don't always work in RHEL. ## GitLab.com The [GitLab.com architecture](https://about.gitlab.com/handbook/engineering/infrastructure/production/architecture/) is detailed for your reference, but this architecture is only useful if you have millions of users.