systemd activated sockets

[cbix]

This is a nice article explaining why systemd's socket activation feature is useful. I personally like it because I don't have to let services open any ports by themselves and I can put everything HTTP behind nginx with a unix socket as upstream, set up with proper permissions (note: nginx' group is www-data on some systems!) + I don't have to remember what's running on which port.

I haven't figured out yet how to make systemd-sysusers to create the user's home directory yet, but theoretically it's also supposed to simplify installation (see the files under deploy/):

# build
./build.sh
# install files (as root)
install prosody-filer /usr/local/bin/prosody-filer
install deploy/prosody-filer.service /usr/local/lib/systemd/system/prosody-filer.service
install deploy/prosody-filer.socket /usr/local/lib/systemd/system/prosody-filer.socket
install deploy/prosody-filer.conf /usr/lib/sysusers.d/prosody-filer.conf
install deploy/prosody-filer.nginx.conf /etc/nginx/sites-available/prosody-filer.nginx.conf
mkdir -p /var/lib/prosody-filer/uploads # or whatever directory is configured in the .service and .toml
install config.example.toml /var/lib/prosody-filer/config.toml
chown -R prosody-filer: /var/lib/prosody-filer

# create user and enable socket
systemd-sysusers
systemctl daemon-reload
systemctl enable prosody-filer.socket

# start socket, the service gets started automatically on the first incoming HTTP request
systemctl start prosody-filer.socket

It is theoretically even possible to provide the service with multiple sockets:

[Socket]
# unix socket
ListenStream=/var/run/prosody-filer.sock
# tcp port over ipv4 + ipv6 on all interfaces
ListenStream=8087
# listen on a specific localhost ipv4 address
ListenStream=127.0.23.42:12345

If prosody-filer is not given any systemd activated sockets, it will simply listen on the port given in the config, so this PR doesn't break compatibility.

[ThomasLeister]

Thanks for letting me know - I'll check this out in detail when there's time for that :-)

[cbix]

Just took a quick look at my code after getting pinged and apparently had initially forgotten to release the WaitGroup mutexes, fixed that now :)

Oh, right, will also try to rebase this to the current state!

[ThomasLeister]

Hi @cbix I've already merged @sysvinit 's approach to unix socket activation. I hope you don't mind if I close this.