gitlab-org--gitlab-foss/doc/administration/high_availability/nfs.md
2016-06-01 14:46:07 -05:00

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NFS

Required NFS Server features

File locking: GitLab requires advisory file locking, which is only supported natively in NFS version 4. NFSv3 also supports locking as long as Linux Kernel 2.6.5+ is used. We recommend using version 4 and do not specifically test NFSv3.

no_root_squash: NFS normally changes the root user to nobody. This is a good security measure when NFS shares will be accessed by many different users. However, in this case only GitLab will use the NFS share so it is safe. GitLab requires the no_root_squash setting because we need to manage file permissions automatically. Without the setting you will receive errors when the Omnibus package tries to alter permissions. Note that GitLab and other bundled components do not run as root but as non-privileged users. The requirement for no_root_squash is to allow the Omnibus package to set ownership and permissions on files, as needed.

When you define your NFS exports, we recommend you also add the following options:

  • sync - Force synchronous behavior. Default is asynchronous and under certain circumstances it could lead to data loss if a failure occurs before data has synced.

Client mount options

Below is an example of an NFS mount point we use on GitLab.com:

10.1.1.1:/var/opt/gitlab/git-data /var/opt/gitlab/git-data nfs4 defaults,soft,rsize=1048576,wsize=1048576,noatime,nobootwait,lookupcache=positive 0 2

Notice several options that you should consider using:

Setting Description
nobootwait Don't halt boot process waiting for this mount to become available
lookupcache=positive Tells the NFS client to honor positive cache results but invalidates any negative cache results. Negative cache results cause problems with Git. Specifically, a git push can fail to register uniformly across all NFS clients. The negative cache causes the clients to 'remember' that the files did not exist previously.

Mount locations

When using default Omnibus configuration you will need to share 5 data locations between all GitLab cluster nodes. No other locations should be shared. The following are the 5 locations you need to mount:

Location Description
/var/opt/gitlab/git-data Git repository data. This will account for a large portion of your data
/var/opt/gitlab/.ssh SSH authorized_keys file and keys used to import repositories from some other Git services
/var/opt/gitlab/gitlab-rails/uploads User uploaded attachments
/var/opt/gitlab/gitlab-rails/shared Build artifacts, GitLab Pages, LFS objects, temp files, etc. If you're using LFS this may also account for a large portion of your data
/var/opt/gitlab/gitlab-ci/builds GitLab CI build traces

Other GitLab directories should not be shared between nodes. They contain node-specific files and GitLab code that does not need to be shared. To ship logs to a central location consider using remote syslog. GitLab Omnibus packages provide configuration for UDP log shipping.

Consolidating mount points

If you don't want to configure 5-6 different NFS mount points, you have a few alternative options.

Change default file locations

Omnibus allows you to configure the file locations. With custom configuration you can specify just one main mountpoint and have all of these locations as subdirectories. Mount /gitlab-data then use the following Omnibus configuration to move each data location to a subdirectory:

user['home'] = '/gitlab-data/home'
git_data_dir '/gitlab-data/git-data'
gitlab_rails['shared_path'] = '/gitlab-data/shared'
gitlab_rails['uploads_directory'] = "/gitlab-data/uploads"
gitlab_ci['builds_directory'] = '/gitlab-data/builds'

To move the git home directory, all GitLab services must be stopped. Run gitlab-ctl stop && initctl stop gitlab-runsvdir. Then continue with the reconfigure.

Run sudo gitlab-ctl reconfigure to start using the central location. Please be aware that if you had existing data you will need to manually copy/rsync it to these new locations and then restart GitLab.

Bind mounts

Bind mounts provide a way to specify just one NFS mount and then bind the default GitLab data locations to the NFS mount. Start by defining your single NFS mount point as you normally would in /etc/fstab. Let's assume your NFS mount point is /gitlab-data. Then, add the following bind mounts in /etc/fstab:

/gitlab-data/git-data /var/opt/gitlab/git-data none bind 0 0
/gitlab-data/.ssh /var/opt/gitlab/.ssh none bind 0 0
/gitlab-data/uploads /var/opt/gitlab/gitlab-rails/uploads none bind 0 0
/gitlab-data/shared /var/opt/gitlab/gitlab-rails/shared none bind 0 0
/gitlab-data/builds /var/opt/gitlab/gitlab-ci/builds none bind 0 0

Read more on high-availability configuration:

  1. Configure the database
  2. Configure Redis
  3. Configure the GitLab application servers
  4. Configure the load balancers