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Configuring a repository cache

You can configure a repository cache for GitHub Enterprise Server by creating a new instance, connecting the repository cache to your primary instance, and configuring replication of repository networks to the repository cache.

About configuration for repository caching

リポジトリ キャッシュと呼ばれる特殊な種類のレプリカを作成することで、リポジトリ キャッシュを構成できます。 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 europe-ci.github.example.com or github.asia.example.com.

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 https://europe-ci.github.example.com/myorg/myrepo.

Configuring a repository cache

  1. 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."

  2. プライマリアプライアンス上のパスワードと一致する管理者パスワードを設定して続行します。

  3. [レプリカとして構成] をクリックします。 新しいインスタンスをレプリカとして設定するリンクがあるインストール オプション

  4. "Add new SSH key(新しいSSH鍵の追加)"の下でSSH鍵を入力してください。 SSH キーの追加

  5. [キーの追加] をクリックします。

  6. Connect to the repository cache's IP address using SSH.

    $ ssh -p 122 admin@REPLICA-IP
  7. レプリケーション用のキーの組を生成するには、プライマリ アプライアンスの IP アドレスを指定して ghe-repl-setup コマンドを使用し、それが返す公開キーをコピーします。

    $ ghe-repl-setup PRIMARY IP
  8. プライマリ アプライアンスの承認されたキーのリストに公開キーを追加するには、https://PRIMARY-HOSTNAME/setup/settings を参照して、レプリカからコピーしたキーをリストに追加します。

  9. To verify the connection to the primary and enable replica mode for the repository cache, run ghe-repl-setup again.

    $ ghe-repl-setup PRIMARY-IP
  10. To configure the repository cache, use the ghe-repl-node command and include the necessary parameters.

    • Set a cache-location for 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 assets or media. For a list of reserved names, see "Enabling subdomain isolation."
    • Set a cache-domain for 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 datacenter for 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
  11. データ ストアのレプリケーションを開始するには、ghe-repl-start コマンドを使います。

    $ ghe-repl-start

    警告: ghe-repl-start を実行すると、プライマリ サーバーを短時間使えなくなり、その間、ユーザーには内部サーバー エラーが表示されることがあります。 もっとわかりやすいメッセージを表示するには、ghe-repl-start をレプリカ ノードで実行する前にプライマリ ノード上で ghe-maintenance -s を実行し、アプライアンスをメンテナンス モードにします。 レプリケーションを開始したら、ghe-maintenance -u を使ってメンテナンス モードを無効にします。 プライマリ ノードがメンテナンス モードの間、Git レプリケーションは進行しません。

  12. 各データストアのレプリケーション チャネルの状態を確認するには、ghe-repl-status コマンドを使用します。

    $ ghe-repl-status
  13. 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.