94 lines
2.7 KiB
Markdown
94 lines
2.7 KiB
Markdown
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# Praefect
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NOTE: **Note:** Praefect is an experimental service, and for testing purposes only at
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this time.
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## Omnibus
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### Architecture
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For this document, the following network topology is assumed:
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```mermaid
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graph TB
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GitLab --> Gitaly;
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GitLab --> Praefect;
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Praefect --> Preafect-Git-1;
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Praefect --> Preafect-Git-2;
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Praefect --> Preafect-Git-3;
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```
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Where `GitLab` is the collection of clients that can request Git operations.
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`Gitaly` is a Gitaly server before using Praefect. The Praefect node has two
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storage nodes attached. Praefect itself doesn't storage data, but connects to
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three Gitaly nodes, `Praefect-Git-1`, `Praefect-Git-2`, and `Praefect-Git-3`.
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There should be no knowledge other than with Praefect about the existence of
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the `Praefect-Git-X` nodes.
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### Enable the daemon
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Praefect is expected to run on their own host, this means that no other service
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other than the support services run on this machine.
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Praefect is disabled by default, to enable praefect uncomment the following line
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and set it to `true`: `# praefect['enable'] = false'`
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```ruby
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praefect['enable'] = true
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```
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By default praefect will listen on port `:2305`. It's recommended to enable
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prometheus to expose metrics. Uncomment the line so it looks like:
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```ruby
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praefect['prometheus_listen_addr'] = "localhost:9652"
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```
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Preafect needs at least one storage to store the Git data on. This node should
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run Gitaly and should not be listed as storage for GitLab itself, that is, the
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only way it receives traffic is through Praefect and it's not listed in the
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`git_data_dirs` on any `gitlab.rb` in your GitLab cluster.
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To set the nodes as depicted in the diagram above, the configuration should look
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like:
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```ruby
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praefect['storage_nodes'] = [
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{
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'storage' => 'praefect-git-1',
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'address' => 'tcp://praefect-git-1.internal',
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'primary' => true
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}
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{
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'storage' => 'praefect-git-2',
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'address' => 'tcp://praefect-git-2.internal'
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},
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{
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'storage' => 'praefect-git-3',
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'address' => 'tcp://praefect-git-3.internal'
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}
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]
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```
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Save the file, and run `gitlab-ctl reconfigure`. To test if Praefect is running,
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you could run `gitlab-ctl status` which should list praefect as being up.
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### Enable Preafect as storage backend in GitLab
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When Praefect is running, it should be exposed as a storage to GitLab. This
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is done through setting the `git_data_dirs`. Assuming the default storage
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configuration is used, there would be two storages available to GitLab:
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```ruby
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git_data_dirs({
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"default" => {
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"gitaly_address" => "tcp://gitaly.internal"
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},
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"praefect" => {
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"gitaly_address" => "tcp://praefect.internal:2305"
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}
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})
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```
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Restart GitLab using `gitlab-ctl restart` on the GitLab node.
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