nginx is not working due to missing /dev/stdout and /dev/stderr

[microsoft]

nginx is not working due to missing /dev/stdout and /dev/stderr

[gupta-ak]

It seems that all the devices are showing up in LCOW as well. The only difference is that stdin/stdout/stderr are sockets in LCOW and in pipes in Linux. Maybe that's causing the issue.
LCOW:

PS> docker run --rm --isolation=hyperv nginx readlink -f /var/log/nginx/access.log
/proc/1/fd/socket:[12131]
PS> docker run --rm --isolation=hyperv nginx readlink -f /var/log/nginx/error.log
/proc/1/fd/socket:[11395]

Linux:

# docker run --rm nginx readlink -f /var/log/nginx/error.log
/proc/1/fd/pipe:[657542]
# docker run --rm nginx readlink -f /var/log/nginx/access.log
/proc/1/fd/pipe:[658449]

[jstarks]

There are also issues with node.js because we are passing vsock sockets as stdin/out/err. We need to relay these sockets, unfortunately. We should only do it for container processes, not "external" processes so that we don't have perf overhead for tar2vhd and related processes.

[jterry75]

Ok looked into this. Just to be clear for container processes we need to wrap the socket based read/writes into a pipe and expose the pipe for /proc/$$/fd/{0, 1, 2}. This unfortunately creates a copy given that the Connection interface doesn't expose a stream based interface but overhead should be minimal if we reuse the buffer.

[gupta-ak]

Wouldn't it be easier to change the service\gcs\runtime\runc\runc.go file and change startProcess to take in an isExternal flag? If it's external, then call stdioSet.Files(). If its not external, just hook up the transports directly. The documentation for os/exec says this:

        // Stdin specifies the process's standard input.
        // If Stdin is nil, the process reads from the null device (os.DevNull).
        // If Stdin is an *os.File, the process's standard input is connected
        // directly to that file.
        // Otherwise, during the execution of the command a separate
        // goroutine reads from Stdin and delivers that data to the command
        // over a pipe. In this case, Wait does not complete until the goroutine
        // stops copying, either because it has reached the end of Stdin
        // (EOF or a read error) or because writing to the pipe returned an error.

So, the wrapping up into a pipe stuff is already handled by Go.

[jstarks]

The problem is that when we do a runc exection, the process exits well before we are done copying the pipe data. So we actually need to spawn copying goroutines manually, and we need to track them, cancel the stdin one, etc. just like we do in the tty case.