#+title: musicfs

* Incus server VM

~musicfs-server~ (gRPC) runs inside an Incus VM, live-sharing the host's
~~/Music~ as a readonly virtiofs mount. =scripts/vm.sh= builds the binary on the
host, bundles its nix ~glibc~ so it runs unmodified in the VM, ships it in, and
runs it under systemd.

** Setup

#+begin_src bash
devenv shell        # cargo, incus, patchelf, grpcurl
scripts/vm.sh up    # create VM, share ~/Music, build, ship, start server
#+end_src

Options (env): =VM_NAME=, =IMAGE=, =MUSIC_SOURCE=, =LISTEN_PORT=, =RUST_LOG=.

| Command                  | Action                        |
|--------------------------+-------------------------------|
| =scripts/vm.sh up=         | create + build + ship + start |
| =scripts/vm.sh redeploy=   | rebuild after a code change   |
| =scripts/vm.sh logs=       | tail server logs              |
| =scripts/vm.sh status=     | VM + service status           |
| =scripts/vm.sh shell=      | shell inside the VM           |
| =scripts/vm.sh down=       | stop the VM                   |
| =scripts/vm.sh destroy=    | delete the VM                 |

** Test it (Nushell)

#+begin_src nushell
let VMIP = (incus list musicfs -f csv -c 4 | lines | first | split row " " | first)
let ADDR = $"($VMIP):50051"

# liveness
^nc -z -w 3 $VMIP 50051
if $env.LAST_EXIT_CODE == 0 { print "alive" } else { print "dead" }

# gRPC: stream the manifest, count entries
grpcurl -plaintext -import-path proto -proto musicfs.proto -d "{}" $ADDR musicfs.MusicFs/GetManifest | lines | find relPath | length

# files the server scans
incus exec musicfs -- find /music -type f | lines | length

# play a track straight out of the VM's shared /music
incus exec musicfs -- cat "/music/DDT/ДДТ - Творчество в пустоте – 2 - 01 Intro.flac" | ^mpv -
#+end_src

Reach the server at the VM's bridge IP (=scripts/vm.sh status= prints it).
Install mpv with =nix profile install nixpkgs#mpv=, or use =^ffplay -= instead.

In Nushell, always put =| lines= between an external command's stdout and a
builtin (=find=, =first=, =length=, ...); external-to-external pipes (=cat |
mpv=) are byte-stable and don't need it.