README.md

Static Responses

There are situations where no backend requests are sent for an endpoint. Nevertheless, a response is needed. So a response block can exist in an endpoint block without any proxy or request blocks.

Example 1: Redirects

Consider the following example, in which the client is instructed to perform a redirect via a 301 status code and a location header specifying the redirect target:

server {
  endpoint "/" {
    response {
      status = 301
      headers = {
        location = "/app/"
      }
    }
  }
}

This could be an example for the good practice of having the SPA paths not under /**.

Call Couper:

$ curl -i localhost:8080/
HTTP/1.1 301 Moved Permanently
Location: /app/
...

Example 2: Userinfo endpoint

Another example is a simple userinfo endpoint, similar to the one defined by OpenID Connect. The endpoint is protected by the "JWTToken" access control. The token claims are reflected to the client.

server {
  endpoint "/userinfo" {
    access_control = ["JWTToken"]
    response {
      status = 200
      json_body = request.context.JWTToken
    }
  }
}

definitions {
  jwt "JWTToken" {
    signature_algorithm = "RS256"
    key_file = "pub.pem"
  }
}

Call Couper using the valid token from the "JWT Access Control" example:

$ curl -H "Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJzb21lX3VzZXIiLCJpc3MiOiJzb21lX3Byb3ZpZGVyIn0.bNXv28XmnFBjirPbCzBqyfpqHKo6PpoFORHsQ-80IJLi3IhBh1y0pFR0wm-2hiz_F7PkGQLTsnFiSXxCt1DZvMstbQeklZIh7O3tQGJyCAi-HRVASHKKYqZ_-eqQQhNr8Ex00qqJWD9BsWVJr7Q526Gua7ghcttmVgTYrfSNDzU" localhost:8080/userinfo
{
  "iss": "some_provider",
  "sub": "some_user"
}

Example 3: Environment variables

As a third example we create a simple configuration endpoint that emits some environment variables. It could be used to initialize the app in the browser. Adding the couper.version might be useful as well.

server {
  endpoint "/app/conf" {
    response {
      json_body = {
        version = env.APP_VERSION
        env = env.APP_ENV
        debug = env.APP_DEBUG == "true"
        couper = couper.version
      }
    }
  }
}

Start Couper with

docker run --rm -e APP_VERSION=1.0 -e APP_ENV=local -e APP_DEBUG=true -p 8080:8080 -v "$(pwd)":/conf coupergateway/couper

and call it with

$ curl localhost:8080/app/conf
{
  "couper": "1.3.1",
  "debug": true,
  "env": "local",
  "version": "1.0"
}

You can play with different values for the environment variables in the docker command line to see how they are reflected in the response.