Docs: Basic documentation for deploying the ruler using jsonnet. (gra…

…fana#2127)

* Docs: Basic documentation for deploying the ruler using jsonnet.

* Fix doc links.

* Move to new file, fix indents, minor rewording.

* Make checks on first migration step more explicit.

* Review comments: Remove redundant text. Add link to configuration parameters.

* Apply suggestions from code review

Co-authored-by: Ursula Kallio <ursula.kallio@grafana.com>

* Review comments.

* Fix doc link filename

* Review comments

Co-authored-by: Ursula Kallio <ursula.kallio@grafana.com>

docs/sources/operators-guide/deploying-grafana-mimir/jsonnet/configuring-ruler.md

@@ -0,0 +1,98 @@
+---
+title: "Configuring the Grafana Mimir ruler with Jsonnet"
+menuTitle: "Configuring ruler"
+description: "Learn how to configure the Grafana Mimir ruler when using Jsonnet."
+weight: 20
+---
+
+# Configuring the Grafana Mimir ruler with Jsonnet
+
+The ruler is an optional component and is therefore not deployed by default when using Jsonnet.
+For more information about the ruler, see [Grafana Mimir ruler]({{< relref "../../architecture/components/ruler/index.md" >}}).
+
+To enable it, add the following Jsonnet code to the `_config` section:
+
+```jsonnet
+_config+:: {
+  ruler_enabled: true
+  ruler_client_type: '<type>',
+}
+```
+
+The `ruler_client_type` option must be one of either `local`, `azure`, `aws`, or `s3`.
+For more information about the options available for storing ruler state, see [Grafana Mimir ruler: State]({{< relref "../../architecture/components/ruler/index.md#state" >}}).
+
+To get started, use the `local` client type for initial testing:
+
+```jsonnet
+_config+:: {
+  ruler_enabled: true
+  ruler_client_type: 'local',
+  ruler_local_directory: '/path/to/local/directory',
+}
+```
+
+If you are using object storage, additional configuration options are required:
+
+- Amazon S3 (`s3`)
+
+  - `ruler_storage_bucket_name`
+  - `aws_region`
+
+- Google Cloud Storage (`gcs`)
+
+  - `ruler_storage_bucket_name`
+
+- Azure (`azure`)
+  - `ruler_storage_bucket_name`
+  - `ruler_storage_azure_account_name`
+  - `ruler_storage_azure_account_key`
+
+> **Note:** You need to manually provide the storage credentials for `s3` and `gcs` by using additional command line arguments as necessary. For more information, see [Grafana Mimir configuration parameters: ruler_storage]({{< relref "../../configuring/reference-configuration-parameters/index.md#ruler_storage" >}}).
+
+## Operational modes
+
+The ruler has two operational modes: _internal_ and _remote_. By default, the Jsonnet deploys the ruler by using the internal operational mode.
+For more information about these modes, see [Operational modes]({{< relref "../../architecture/components/ruler/index.md#operational-modes" >}}).
+
+To enable the remote operational mode, add the following code to the Jsonnet:
+
+```jsonnet
+_config+:: {
+  ruler_remote_evaluation_enabled: true
+}
+```
+
+> **Note:** To support the _remote_ operational mode, a separate query path is deployed to evaluate rules that consist of three additional Kubernetes deployments:
+>
+> - `ruler-query-frontend`
+> - `ruler-query-scheduler`
+> - `ruler-querier`
+
+### Migrate to remote evaluation
+
+To perform a zero downtime migration from internal to remote rule evaluation, follow these steps:
+
+1. Deploy the following changes to enable remote evaluation in migration mode.
+   Doing so causes the three new and previously listed Kubernetes deployments to start. However, they will not reconfigure the ruler to use them just yet.
+
+   ```jsonnet
+   _config+:: {
+     ruler_remote_evaluation_enabled: true
+     ruler_remote_evaluation_migration_enabled: true
+   }
+   ```
+
+1. Check that all of pods for the following deployments have successfully started before moving to the next step:
+
+   - `ruler-query-frontend`
+   - `ruler-query-scheduler`
+   - `ruler-querier`
+
+1. Reconfigure the ruler pods to perform remote evaluation, by deploying the following changes:
+
+   ```jsonnet
+   _config+:: {
+     ruler_remote_evaluation_enabled: true
+   }
+   ```