NFS3 demo server

[weissi]

Motivation:

Previously (#155), we added support for the NFS3 protocol. But without actually having a demo server, that's not actually very much fun.

Modifications:

Add a demo server which can mount a simple dummy file system in user space.

Result:

Better demo

---

How to try this out? Just swift run NIOExtrasNFS3Demo and then you should see

2023-08-17T14:55:23+0100 info com.apple.swift-nio-extras-nfs3-demo : address=[IPv4]127.0.0.1/127.0.0.1:55507 pid=45446 [NIOExtrasNFS3Demo] FileSystemServer up and running
2023-08-17T14:55:23+0100 info com.apple.swift-nio-extras-nfs3-demo : mount-command=/sbin/mount -o ro,dumbtimer,timeo=100,deadtimeout=300,port=55507,mountport=55507,acregmin=31536000,acregmax=31536000,acdirmin=31536000,acdirmax=31536000,locallocks -t nfs 127.0.0.1:// /tmp/mount --  [NIOExtrasNFS3Demo] attempting mount
2023-08-17T14:55:23+0100 info com.apple.swift-nio-extras-nfs3-demo : mount-point=/tmp/mount [NIOExtrasNFS3Demo] mount successful

which means it successfully mounted the filesystem at /tmp/mount. You can then check it out

$ find /tmp/mount
/tmp/mount
/tmp/mount/dir
/tmp/mount/dir/file
/tmp/mount/dir/file1
/tmp/mount/dir/file2
/tmp/mount/dir/file3
/tmp/mount/dir/file4
/tmp/mount/dir/file5
$ head -c 20 /tmp/mount/dir/file1
HEEEEEEEEEEEEEEEEEEE
$ 

to unmount press Ctrl+C in the NIOExtrasNFS3Demo process.

[Lukasa]

Ideally we'd avoid the swift-log dependency here. Any reason we can't print?

[weissi]

We use the logger to carry metadata through. So if you get an error in your file system, you can log and you'll get the precise connection etc associated. For production that's important and given that I had the code I left it here too because I thought the swift-log dependency wouldn't be too bad.

But I can take it out, lose the metadata propagation and just use print(...)

[Lukasa]

It's definitely not too bad, and I could be talked out of this, but in general keeping the dependency tree small is kinda nice. No strong feelings though, happy for someone to try to talk me out of it.

[weissi]

Similar position but the other way around. Happy either way really ;)