Passing Header Fields to the Client

To add arbitrary header fields sent by the upstream system to the client response use the set-response-headers action together with pair producers to copy the wanted header fields of the incoming upstream response ($upstream/<request ID>/headers). Here we pass Content-Type and Cache-Control:

<flow>
  <request content="httpbin">{ "url": "http://httpbin.org/cache/600" }</request>

  <set-response-headers>
  {
    {{: $upstream/httpbin/headers/content-type }}
    {{: $upstream/httpbin/headers/cache-control }}
  }
  </set-response-headers>
</flow>

Both expressions can be combined to

  {
    {{: $upstream/httpbin/headers/content-type | $upstream/httpbin/headers/cache-control }}
  }

which in turn may be shortened using with:

  {
    {{with $upstream/httpbin/headers }} {{: content-type | cache-control }} {{end}}
  }