Merge pull request #209 from pet-forks/http2_websockets

Add docs for HTTP/2 WebSockets

Author: mjgutermuth

supporting-http2.html.md.erb

@@ -71,6 +71,12 @@ For more information, see [Starting HTTP/2 with Prior Knowledge](https://datatra
 Layer 7 load balancers terminate the incoming HTTP connection and initiate new HTTP connections to their back ends.
 For end-to-end HTTP/2 support, Layer 7 load balancers must have HTTP/2 enabled for both ingress and egress HTTP connections.
 
+Gorouter and many Layer 7 load balancers do not support WebSockets over HTTP/2 ([RFC 8441](https://datatracker.ietf.org/doc/html/rfc8441)).
+WebSockets are used by <%= vars.app_runtime_abbr %> for streaming logs and metrics, in addition to apps that serve WebSocket traffic.
+Because of this, load balancers should be configured to forward WebSocket traffic over HTTP/1.1.
+Alternatively, you may use a Layer 4 load balancer for WebSockets traffic.
+For more information, see <a href='../adminguide/supporting-websockets.html'>Supporting WebSockets</a>.
+
 For example, the HAProxy BOSH release contains the canonical example of how to set up HTTP/2 load balancing for <%= vars.app_runtime_abbr %>.
 See the [BOSH release for HAProxy](https://github.com/cloudfoundry-incubator/haproxy-boshrelease) on GitHub.
 

supporting-websockets.html.md.erb

@@ -39,6 +39,10 @@ To form a WebSocket connection, the client sends an HTTP request that contains a
 These requests return a 503 error and a <code>X-Cf-Routererror
 	route_service_unsupported</code> header.</p>
 
+<p class="note"><strong>Note:</strong> Gorouter does not support WebSockets over HTTP/2 (<a href='https://datatracker.ietf.org/doc/html/rfc8441'>RFC 8441</a>).
+Your load balancer should always send WebSocket requests to Gorouter over HTTP/1.1.
+For more information, see <a href='../adminguide/supporting-http2.html#load-balancer'>Configuring HTTP/2 Support </a>.</p>
+
 ## <a id='modify'></a> Set Your Loggregator Port
 
 <% if vars.platform_code == 'CF' %>