Merge pull request #1540 from cortexproject/api-docs

Add a doc for APIs

Author: bboreham

docs/configs-api.md renamed to docs/apis.md

@@ -1,16 +1,31 @@
-# Configs API
+# Cortex APIs
+
+[this is a work in progress]
+
+## Remote API
+
+Cortex supports Prometheus'
+[`remote_read`](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_read)
+and
+[`remote_write`](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write)
+APIs.  The encoding is Protobuf over http.
+
+Read is on `/api/prom/read` and write is on `/api/prom/push`.
+
+
+## Configs API
 
 The configs service provides an API-driven multi-tenant approach to handling various configuration files for prometheus. The service hosts an API where users can read and write Prometheus rule files, Alertmanager configuration files, and Alertmanager templates to a database.
 
 Each tenant will have it's own set of rule files, Alertmanager config, and templates. A POST operation will effectively replace the existing copy with the configs provided in the request body.
 
-## Configs Format
+### Configs Format
 
 At the current time of writing, the API is part-way through a migration from a single Configs service that handled all three sets of data to a split API ([Tracking issue](https://github.com/cortexproject/cortex/issues/619)). All APIs take and return all sets of data.
 
 The following schema is used both when retrieving the current configs from the API and when setting new configs via the API.
 
-### Schema:
+#### Schema:
 
 ```json
 {
@@ -30,7 +45,7 @@ The following schema is used both when retrieving the current configs from the A
 }
 ```
 
-### Formatting
+#### Formatting
 
 `id` - should be incremented every time data is updated; Cortex will use the config with the highest number.
 
@@ -42,9 +57,9 @@ The following schema is used both when retrieving the current configs from the A
 
 `config.template_files` - The contents of a template file should be as described [here](https://prometheus.io/docs/alerting/notification_examples/#defining-reusable-templates), encoded as a single string to fit within the overall JSON payload.
 
-## Endpoints
+### Endpoints
 
-### Manage Alertmanager
+#### Manage Alertmanager
 
 `GET /api/prom/configs/alertmanager` - Get current Alertmanager config
 
@@ -73,7 +88,7 @@ Error Response: BadRequest(400)
 }
 ```
 
-### Manage Rules
+#### Manage Rules
 
 `GET /api/prom/configs/rules` - Get current rule files
 
@@ -85,7 +100,7 @@ Error Response: BadRequest(400)
 - Normal Response Codes: NoContent(204)
 - Error Response Codes: Unauthorized(401), BadRequest(400)
 
-### Manage Templates
+#### Manage Templates
 
 `GET /api/prom/configs/templates` - Get current templates
 
@@ -97,7 +112,7 @@ Error Response: BadRequest(400)
 - Normal Response Codes: NoContent(204)
 - Error Response Codes: Unauthorized(401), BadRequest(400)
 
-### Deactivate/Restore Configs
+#### Deactivate/Restore Configs
 
 `DELETE /api/prom/configs/deactivate` - Disable configs for a tenant