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authorLee Matos <lee@gitlab.com>2018-10-30 17:17:54 +0000
committerLee Matos <lee@gitlab.com>2018-10-30 17:17:54 +0000
commitfce93f3c2d675af065db6632ba61772333919e50 (patch)
treeb2791a0ba2d4657e9bc664144e145c3ba04d561f
parent50f5ee1a31fae31341ea8debd05f53fe4fada31a (diff)
downloadgitlab-ce-lm-update-architecture-docs.tar.gz
Update architecture.md with linting passlm-update-architecture-docs
-rw-r--r--doc/development/architecture.md136
1 files changed, 73 insertions, 63 deletions
diff --git a/doc/development/architecture.md b/doc/development/architecture.md
index ee20975d171..01d99c46f89 100644
--- a/doc/development/architecture.md
+++ b/doc/development/architecture.md
@@ -10,13 +10,13 @@ For information, see the [GitLab Release Process](https://gitlab.com/gitlab-org/
Both EE and CE require some add-on components called gitlab-shell and Gitaly. These components are available from the [gitlab-shell](https://gitlab.com/gitlab-org/gitlab-shell/tree/master) and [gitaly](https://gitlab.com/gitlab-org/gitaly/tree/master) repositories respectively. New versions are usually tags but staying on the master branch will give you the latest stable version. New releases are generally around the same time as GitLab CE releases with exception for informal security updates deemed critical.
-# GitLab Omnibus Component by Component
+## GitLab Omnibus Component by Component
This document is designed to be consumed by systems adminstrators 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.
+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.
-## GitLab Process Descriptions
+### GitLab Process Descriptions
As of this writing, a fresh GitLab 11.3.0 install will show the following processes with `gitlab-ctl status`:
@@ -37,137 +37,147 @@ run: sidekiq: (pid 30953) 14205s; run: log: (pid 13810) 2432047s
run: unicorn: (pid 30960) 14204s; run: log: (pid 13809) 2432047s
```
-## Layers
+### 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 will allow 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 as platform. If any of these processes halt there will be a GitLab outage. 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.
+- **Monitoring**: Anything from this layer is not required to deliver GitLab the application, but will allow 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 as platform. If any of these processes halt there will be a GitLab outage. 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
+### alertmanager
-+ Omnibus configuration options
-+ Layer: Monitoring
+- Omnibus configuration options
+- Layer: Monitoring
[Alert manager](https://prometheus.io/docs/alerting/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 gitlab-ce#45740](https://gitlab.com/gitlab-org/gitlab-ce/issues/45740) about what we will be alerting on.
-## gitaly
-+ [Omnibus confiugration options](https://gitlab.com/gitlab-org/gitaly/tree/master/doc/configuration)
-+ Layer: Core Service (Data)
+### gitaly
+
+- [Omnibus confiugration options](https://gitlab.com/gitlab-org/gitaly/tree/master/doc/configuration)
+- Layer: Core Service (Data)
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 Availablity 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).
+### gitlab-monitor
-## gitlab-monitor
-+ Omnibus configuration options
-+ Layer: Monitoring
+- Omnibus configuration options
+- Layer: Monitoring
GitLab Monitor is a process disigned 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-monitor)
-## gitlab-workhorse
-+ Omnibus configuration options
-+ Layer: Core Service (Processor)
+### gitlab-workhorse
+
+- Omnibus configuration options
+- Layer: Core Service (Processor)
[GitLab Workhorse](https://gitlab.com/gitlab-org/gitlab-workhorse) is a program designed at GitLab to help alieviate pressure from unicorn. You can read more about the [historical reasons for developing](https://about.gitlab.com/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.
+### logrotate
-## logrotate
-+ [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/logs.html#logrotate)
-+ Layer: Core Service
+- [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/logs.html#logrotate)
+- Layer: Core Service
GitLab is comprised of a large number of services that all log. We started bundling our own logrotate as of 7.4 to make sure we were logging responsibly. This is just a packaged version of the common opensource offering.
-## nginx
-+ [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/nginx.html)
-+ Layer: Core Service (Processor)
+### nginx
+
+- [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/nginx.html)
+- Layer: Core Service (Processor)
Nginx as as an ingress port for all HTTP requests and routes them to the approriate sub-systems within GitLab. We are bundling an unmodified version of the popular open source webserver.
+### node-exporter
-## node-exporter
-+ [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/node_exporter.html)
-+ Layer: Monitoring
+- [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/node_exporter.html)
+- Layer: 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.
-## postgres-exporter
-+ [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/postgres_exporter.html)
-+ Layer: Monitoring
+### postgres-exporter
+
+- [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/postgres_exporter.html)
+- Layer: Monitoring
[Postgres-exporter](https://github.com/wrouesnel/postgres_exporter) is the community provided Prometheus exporter that will deliver data about Postgres to prometheus for use in Grafana Dashboards.
-## postgresql
-+ [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/database.html)
-+ Layer: Core Service (Data)
+### postgresql
+
+- [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/database.html)
+- Layer: Core Service (Data)
GitLab packages the popular Database to provide storage for Application meta data and user information.
-## prometheus
-+ [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/)
-+ Layer: Monitoring
+### prometheus
+
+- [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/)
+- Layer: Monitoring
Prometheus is a time-series tool that helps GitLab administrators expose metrics about the individual processes used to provide GitLab the service.
-## redis
-+ [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/redis.html)
-+ Layer: Core Service (Data)
+### redis
+
+- [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/redis.html)
+- Layer: Core Service (Data)
Redis is packaged to provide a place to store:
-+ session data
-+ temporary cache information
-+ background job queues.
+- session data
+- temporary cache information
+- background job queues.
+### redis-exporter
-## redis-exporter
-+ [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/redis_exporter.html)
-+ Layer: Monitoring
+- [Omnibus configuration options](https://docs.gitlab.com/ee/administration/monitoring/prometheus/redis_exporter.html)
+- Layer: 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 Graphana.
+### sidekiq
-## sidekiq
-+ Omnibus configuration options
-+ Layer: Core Service (Processor)
+- Omnibus configuration options
+- Layer: Core Service (Processor)
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.
-## unicorn
-+ [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/unicorn.html)
-+ Layer: Core Service (Processor)
+### unicorn
+
+- [Omnibus configuration options](https://docs.gitlab.com/omnibus/settings/unicorn.html)
+- Layer: Core Service (Processor)
[Unicorn](https://bogomips.org/unicorn/) is a Ruby application server that is used to run the core Rails Application that provides the user facing features in GitLab. Often process output you will see this as `bundle` or `config.ru` depending on the GitLab version.
-## Additional Processes
+### Additional Processes
### GitLab Pages
+
TODO
### Mattermost
+
TODO
-# GitLab by Request Type
+## 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)
+- 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
+### GitLab Web HTTP Request Cycle
When making a request to an HTTP Endpoint (Think `/users/sign_in`) the request will take 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 unicorn.
-+ unicorn - Since this is a web request, and it needs to access the application it will go to Unicorn.
-+ Postgres/Gitaly/Redis - Depending on the type of request, it may hit these services to store or retreive data.
+- 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 unicorn.
+- unicorn - Since this is a web request, and it needs to access the application it will go to Unicorn.
+- Postgres/Gitaly/Redis - Depending on the type of request, it may hit these services to store or retreive data.
-## GitLab Git Request Cycle
+### GitLab Git Request Cycle
Below we describe the different pathing that HTTP vs. SSH Git requests will take. There is some overlap with the Web Request Cycle but also some differences.