websocket SOP

WebSocket is a protocol (an extension of HTTP/1.1) by which client web browsers can establish full-duplex socket communications with a server --the "real-time web".

In our case, webapps served from app0* and packages0* will include javascript code instructing client browsers to establish a second connection to our WebSocket server. They point browsers to the following addresses:

The websocket server itself is a fedmsg-hub daemon running on busgateway01. It is configured to enable its websocket server component in the presence of certain configuration values.

haproxy mediates connections to the fedmsg-hub websocket server daemon. An stunnel daemon provides SSL support.

The connection flow is much the same as in the fedmsg-gateway SOP, but is somewhat more complicated.

"Normal" HTTP requests to our app servers traverse the following chain:

The flow for a websocket requests looks something like this:

stunnel is listening on a public port, negotiates the SSL connection, and redirects the connection to haproxy who in turn hands it off to the fedmsg-hub websocket server listening on busgateway01.

At the time of this writing, haproxy does not actually load balance zeromq session requests across multiple busgateway0* machines, but there is nothing stopping us from adding them. New hosts can be added in ansible and pressed from busgateway01's template. Add them to the fedmsg-websockets listen in haproxy's config and it should Just Work.

We had RHIT open up port 9939 special to proxy01.iad2 for this.