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Comment by leephillips | Hacker News Reader

“It turns out both nginx and Apache have the ability to proxy traffic to a Unix domain socket rather than to an HTTP port, which makes this a useful mechanism for running backend servers without attaching them to TCP ports.”

That’s one useful nugget of information! I had no idea.

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On webide.se (free shell and web IDE) I use unix sockets alot!, for example nginx proxy from https://foo.user.webide.se to /home/user/socket/foo so that users can test their apps using HTTPS/SSL as many browser features need a httpS URL to work. Unix sockers are also used for accessing a shared mySQL server, and an x11 server so you can test out "native" apps and run Android emulator in the browser.

TIL

Now Docker should provide some way to bridge container ports to UDS. That would be perfect.

You can bind mount the socket in a volume. You can also do this with named volumes shared between containers. You’ll need to make sure the GID/UIDs match, but it works great. It’s often faster for inter service communication than the Docker proxy.

Quick hack for you:

socat TCP-LISTEN:4000,fork UNIX-CONNECT:/run/yoursock

HAProxy can as well (as well as listen on unix sockets)

And Envoy Proxy (with an example [0])

0. https://gist.github.com/moderation/5d9c5352842ca068781f367a6...

Unfortunately and annoyingly not all applications support listening on Unix domain sockets.

socat is the tool for this. No need for a full blown webserver.

socat is a "dumb" tool. With a proxy that understands HTTP you have a lot more influence over what goes where and for example not direct requests to a down backend instance.

Are you challenging me to build a socat loadbalancer in bash? In all seriousness, I concur. But if you just need to redirect some data streams socat is a rock solid and simple solution.

> Are you challenging me to build a socat loadbalancer in bash?

It’s a Saturday and all, so yeah, I’m challenging you (for fun, not because I don’t think it’s possible).

From a quick read of the manpage, I don't think it's possible either, unless you mess with EXEC or create multiple listeners to a single address.

Anyway, the Linux kernel does have a builtin loadbalancer in the form of shared sockets that you can socat outside of the machine. But I wouldn't call that a socat loadbalancer.

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