About configuration for repository caching
You can configure repository caching by creating a special type of replica called a repository cache. Then, you can set data location policies that govern which repository networks are replicated to the repository cache.
Repository caching is not supported with clustering.
DNS for repository caches
The primary instance and repository cache should have different DNS names. For example, if your primary instance is at
github.example.com, you might decide to name a cache
To have your CI machines fetch from the repository cache instead of the primary instance, you can use Git's
url.<base>.insteadOf configuration setting. For more information, see
git-config in the Git documentation.
For example, the global
.gitconfig for the CI machine would include these lines.
[url "https://europe-ci.github.example.com/"] insteadOf = https://github.example.com/
Then, when told to fetch
https://github.example.com/myorg/myrepo, Git will instead fetch from
Configuring a repository cache
Set up a new GitHub Enterprise Server instance on your desired platform. This instance will be your repository cache. For more information, see "Setting up a GitHub Enterprise Server instance."
Set an admin password that matches the password on the primary appliance and continue.
Click Configure as Replica.
Under "Add new SSH key", type your SSH key.
Click Add key.
Connect to the repository cache's IP address using SSH.
$ ssh -p 122 admin@REPLICA-IP
To generate a key pair for replication, use the
ghe-repl-setupcommand with the primary appliance's IP address and copy the public key that it returns.
$ ghe-repl-setup PRIMARY_IP
To add the public key to the list of authorized keys on the primary appliance, browse to
https://PRIMARY-HOSTNAME/setup/settingsand add the key you copied from the replica to the list.
To verify the connection to the primary and enable replica mode for the repository cache, run
$ ghe-repl-setup PRIMARY-IP
To configure the repository cache, use the
ghe-repl-nodecommand and include the necessary parameters.
- Set a
cache-locationfor the repository cache, replacing CACHE-LOCATION with an alphanumeric identifier, such as the region where the cache is deployed. The CACHE-LOCATION value must not be any of the subdomains reserved for use with subdomain isolation, such as
media. For a list of reserved names, see "Enabling subdomain isolation."
- Set a
cache-domainfor the repository cache, replacing EXTERNAL-CACHE-DOMAIN with the hostname Git clients will use to access the repository cache. If you do not specify a
cache-domain, GitHub Enterprise Server will prepend the CACHE-LOCATION value as a subdomain to the hostname configured for your instance. For more information, see "Configuring a hostname."
- New caches will attempt to seed from another cache in the same datacenter. Set a
datacenterfor the repository cache, replacing REPLICA-DC-NAME with the name of the datacenter where you're deploying the node.
$ ghe-repl-node --cache CACHE-LOCATION --cache-domain EXTERNAL-CACHE-DOMAIN --datacenter REPLICA-DC-NAME
- Set a
To start replication of the datastores, use the
ghe-repl-startcauses a brief outage on the primary server, during which users may see internal server errors. To provide a friendlier message, run
ghe-maintenance -son the primary node before running
ghe-repl-starton the replica node to put the appliance in maintenance mode. Once replication starts, disable maintenance mode with
ghe-maintenance -u. Git replication will not progress while the primary node is in maintenance mode.
To verify the status of each datastore's replication channel, use the
To enable replication of repository networks to the repository cache, set a data location policy. For more information, see "Data location policies."
Data location policies
You can control data locality by configuring data location policies for your repositories with the
spokesctl cache-policy command. Data location policies determine which repository networks are replicated on which repository caches. By default, no repository networks will be replicated on any repository caches until a data location policy is configured.
Data location policies affect only Git content. Content in the database, such as issues and pull request comments, will be replicated to all nodes regardless of policy.
Note: Data location policies are not the same as access control. You must use repository roles to control which users may access a repository. For more information about repository roles, see "Repository roles for an organization."
You can configure a policy to replicate all networks with the
--default flag. For example, this command will create a policy to replicate a single copy of every repository network to the set of repository caches whose
cache_location is "kansas".
$ ghe-spokesctl cache-policy set --default 1 kansas
To configure replication for a repository network, specify the repository that is the root of the network. A repository network includes a repository and all of the repository's forks. You cannot replicate part of a network without replicating the whole network.
$ ghe-spokesctl cache-policy set <owner/repository> 1 kansas
You can override a policy that replicates all networks and exclude specific networks by specifying a replica count of zero for the network. For example, this command specifies that any repository cache in location "kansas" cannot contain any copies of that network.
$ ghe-spokesctl cache-policy set <owner/repository> 0 kansas
Replica counts greater than one in a given cache location are not supported.