Snapcraft Socket missing Backlog?

snapd
1

Snapcraft Service’s have several config options similar to systemd. For instance, listen-stream and mode etc. https://snapcraft.io/docs/services-and-daemons

However, there is no Backlog in Snapcraft as there is in systemd?

[Socket]

ListenStream=xyz

Backlog=10

SocketMode=0660

How would one set the Backlog in a Snap Socket?

2

You wouldn’t. It needs to be added to snapd first to work ootb. Nobody has asked for that yet, so happy to review a pull request if you with to give it a try.

Alternatively, you can maybe have a local drop-in config. The socket unit name is predictable, so you could write a file like this:

# /etc/systemd/system/snap.foo.bar.baz.socket.d/99-override.conf
[Socket]
Backlog=<your-value>

where foo.bar.baz corresponds to a snap foo, having a daemon bar, which lists activation socket of name baz.

BTW. is the default not good enough? I think it’s usually set to 4096+.

3

Well, the default is actually too big. I am migrating some services into a Snap and they set their Backlog to 10. I didn’t want to mess with that.

I appreciate the workaround – but I’m pretty sure that wont work on Ubuntu Core?

4

I’ll work the same. You’ll have to access the device to put the file there.

5

Yes. However, it appears when you are within the snap you can write to /etc/systemd/system so perhaps this is also a workaround.

I found myself having no choice but to do this since, also, snapcraft is missing Type=exec. Snapcraft only supports Type=simple. There is a minor difference here but THERE IS a difference.

All services in my snapcraft are set not to launch are snap install time. This gives me time to run:

find /etc/systemd/system -type f -name “snap.thio*.service” -exec sed -i ‘s/Type=simple/Type=exec/g’ {} +

thio == my snap name