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gitlab-org--gitlab-foss/doc/user/gitlab_com/index.md
Achilleas Pipinellis 433a6b02d3
Move GitLab.com settings under main docs
2018-03-23 17:48:03 +01:00

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GitLab.com settings

In this page you will find information about the settings that are used on GitLab.com.

SSH host keys fingerprints

Below are the fingerprints for GitLab.com's SSH host keys.

Algorithm MD5 SHA256
DSA 7a:47:81:3a:ee:89:89:64:33:ca:44:52:3d:30:d4:87 p8vZBUOR0XQz6sYiaWSMLmh0t9i8srqYKool/Xfdfqw
ECDSA f1:d0:fb:46:73:7a:70:92:5a:ab:5d:ef:43:e2:1c:35 HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw
ED25519 2e:65:6a:c8:cf:bf:b2:8b:9a:bd:6d:9f:11:5c:12:16 eUXGGm1YGsMAS7vkcx6JOJdOGHPem5gQp4taiCfCLB8
RSA b6:03:0e:39:97:9e:d0:e7:24:ce:a3:77:3e:01:42:09 ROQFvPThGrW4RuWLoL9tq9I9zJ42fK4XywyRtbOz/EQ

Mail configuration

GitLab.com sends emails from the mg.gitlab.com domain via Mailgun and has its own dedicated IP address (198.61.254.240).

Alternative SSH port

GitLab.com can be reached via a different SSH port for git+ssh.

Setting Value
Hostname altssh.gitlab.com
Port 443

An example ~/.ssh/config is the following:

Host gitlab.com
  Hostname altssh.gitlab.com
  User git
  Port 443
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/gitlab

GitLab Pages

Below are the settings for GitLab Pages.

Setting GitLab.com Default
Domain name gitlab.io -
IP address 52.167.214.135 -
Custom domains support yes no
TLS certificates support yes no

The maximum size of your Pages site is regulated by the artifacts maximum size which is part of GitLab CI.

GitLab CI/CD

Below are the current settings regarding GitLab CI/CD.

Setting GitLab.com Default
Artifacts maximum size 1G 100M

Shared Runners

Shared Runners on GitLab.com run in autoscale mode and powered by DigitalOcean. Autoscaling means reduced waiting times to spin up builds, and isolated VMs for each project, thus maximizing security.

They're free to use for public open source projects and limited to 2000 CI minutes per month per group for private projects. Read about all GitLab.com plans.

All your builds run on 2GB (RAM) ephemeral instances, with CoreOS and the latest Docker Engine installed. The default region of the VMs is NYC.

Below are the shared Runners settings.

Setting GitLab.com Default
GitLab Runner Runner versions dashboard -
Executor docker+machine -
Default Docker image ruby:2.1 -
privileged (run Docker in Docker) true false

config.toml

The full contents of our config.toml are:

[[runners]]
  name = "docker-auto-scale"
  limit = X
  request_concurrency = X
  url = "https://gitlab.com/ci"
  token = "SHARED_RUNNER_TOKEN"
  executor = "docker+machine"
  environment = [
    "DOCKER_DRIVER=overlay2"
  ]
  [runners.docker]
    image = "ruby:2.1"
    privileged = true
  [runners.machine]
    IdleCount = 40
    IdleTime = 1800
    MaxBuilds = 1
    MachineDriver = "digitalocean"
    MachineName = "machine-%s-digital-ocean-2gb"
    MachineOptions = [
      "digitalocean-image=coreos-stable",
      "digitalocean-ssh-user=core",
      "digitalocean-access-token=DIGITAL_OCEAN_ACCESS_TOKEN",
      "digitalocean-region=nyc1",
      "digitalocean-size=2gb",
      "digitalocean-private-networking",
      "digitalocean-userdata=/etc/gitlab-runner/cloudinit.sh",
      "engine-registry-mirror=http://IP_TO_OUR_REGISTRY_MIRROR"
    ]
  [runners.cache]
    Type = "s3"
    ServerAddress = "IP_TO_OUR_CACHE_SERVER"
    AccessKey = "ACCESS_KEY"
    SecretKey = "ACCESS_SECRET_KEY"
    BucketName = "runner"
    Shared = true

Sidekiq

GitLab.com runs Sidekiq with arguments --timeout=4 --concurrency=4 and the following environment variables:

Setting GitLab.com Default
SIDEKIQ_MEMORY_KILLER_MAX_RSS 1000000 1000000
SIDEKIQ_MEMORY_KILLER_SHUTDOWN_SIGNAL SIGKILL -
SIDEKIQ_LOG_ARGUMENTS 1 -

Cron jobs

Periodically executed jobs by Sidekiq, to self-heal Gitlab, do external synchronizations, run scheduled pipelines, etc.:

Setting GitLab.com Default
pipeline_schedule_worker 19 * * * * 19 * * * *

PostgreSQL

GitLab.com being a fairly large installation of GitLab means we have changed various PostgreSQL settings to better suit our needs. For example, we use streaming replication and servers in hot-standby mode to balance queries across different database servers.

The list of GitLab.com specific settings (and their defaults) is as follows:

Setting GitLab.com Default
archive_command /usr/bin/envdir /etc/wal-e.d/env /opt/wal-e/bin/wal-e wal-push %p empty
archive_mode on off
autovacuum_analyze_scale_factor 0.01 0.01
autovacuum_max_workers 6 3
autovacuum_vacuum_cost_limit 1000 -1
autovacuum_vacuum_scale_factor 0.01 0.02
checkpoint_completion_target 0.7 0.9
checkpoint_segments 32 10
effective_cache_size 338688MB Based on how much memory is available
hot_standby on off
hot_standby_feedback on off
log_autovacuum_min_duration 0 -1
log_checkpoints on off
log_line_prefix %t [%p]: [%l-1] empty
log_min_duration_statement 1000 -1
log_temp_files 0 -1
maintenance_work_mem 2048MB 16 MB
max_replication_slots 5 0
max_wal_senders 32 0
max_wal_size 5GB 1GB
shared_buffers 112896MB Based on how much memory is available
shared_preload_libraries pg_stat_statements empty
shmall 30146560 Based on the server's capabilities
shmmax 123480309760 Based on the server's capabilities
wal_buffers 16MB -1
wal_keep_segments 512 10
wal_level replica minimal
statement_timeout 15s 60s
idle_in_transaction_session_timeout 60s 60s

Some of these settings are in the process being adjusted. For example, the value for shared_buffers is quite high and as such we are looking into adjusting it. More information on this particular change can be found at https://gitlab.com/gitlab-com/infrastructure/issues/1555. An up to date list of proposed changes can be found at https://gitlab.com/gitlab-com/infrastructure/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name[]=database&label_name[]=change.

Unicorn

GitLab.com adjusts the memory limits for the unicorn-worker-killer gem.

Base default:

  • memory_limit_min = 750MiB
  • memory_limit_max = 1024MiB

Web front-ends:

  • memory_limit_min = 1024MiB
  • memory_limit_max = 1280MiB

GitLab.com at scale

In addition to the GitLab Enterprise Edition Omnibus install, GitLab.com uses the following applications and settings to achieve scale. All settings are located publicly available chef cookbooks.

ELK

We use Elasticsearch, logstash, and Kibana for part of our monitoring solution:

Prometheus

Prometheus complete our monitoring stack:

Grafana

For the visualization of monitoring data:

Sentry

Open source error tracking:

Consul

Service discovery:

Haproxy

High Performance TCP/HTTP Load Balancer: