Add documentation #59

docs/README.md

@@ -123,6 +123,7 @@ Environment variables can be accessed everywhere within the configuration file s
 | `headers.<name>` | HTTP request header value for requested lower-case key|
 | `cookies.<name>` | value from `Cookie` request header for requested key (&#9888; last wins!)|
 | `query.<name>` | query parameter values (&#9888; last wins!)|
+| `path_param.<name>` | value from a named path parameter defined within an endpoint path label |
 | `post.<name>` | post form parameter |
 | `json_body.<name>` | Access json decoded object properties. Media type must be `application/json`. |
 | `ctx.<name>.<claim_name>` | request context containing claims from JWT used for [access control](#access_control_attribute), `<name>` being the [`jwt` block's](#jwt_block) label and `claim_name` being the claim's name|
@@ -271,6 +272,16 @@ Endpoints define the entry points of Couper. The mandatory *label* defines the p
 |[**`access_control`**](#access_control_attribute)|sets predefined `access_control` for `endpoint`|
 |[**`backend`**](#backend_block) block |configures connection to a local/remote backend service for `endpoint`|
 
+#### Path parameter
+
+An endpoint label could be defined as `endpoint "/app/{section}/{project}/view" { ... }` to access the named path parameter `section` and `project` via `req.path_param.*`.
+The values would map as following for the request path: `/app/nature/plant-a-tree/view`:
+
+| Variable                 | Value          |
+|:-------------------------|:---------------|
+| `req.path_param.section` | `nature` |
+| `req.path_param.project` | `plant-a-tree` |
+
 ### The `backend` block <a name="backend_block"></a>
 A `backend` defines the connection to a local/remote backend service. Backends can be defined globally in the `api` block for all endpoints of an API or inside an `endpoint`. An `endpoint` must have (at least) one `backend`. You can also define backends in the `definitions` block and use the mandatory *label* as reference.