ubuntu 16.04 docker image should include netbase

[Pierce Lopez]

I attempted to run munin-update from package "munin", inside a docker container based on the ubuntu:16.04 image. It failed to connect to any nodes with a strange error: "No such file or directory".

I narrowed it down to a tiny testcase just using IO::Socket::INET6->new(), which seemed to work fine outside a container, but fail strangely inside the container. Using strace I figured out that it needs /etc/protocols, which is from netbase, which is not present by default in the image. Installing netbase fixed the problem. It seems like a small and basic piece of infrastructure.

So there it is. libio-socket-inet6-perl needs /etc/protocols from netbase, but the package does not express that, probably because it's assumed to be present on all debian systems as a minimum sane base. It's 68 KiB.

I've attached the minimal testcase (depends on libio-socket-inet6-perl).

[Pierce Lopez (pierce-lopez)]

Note that IO::Socket::INET6 is not just for ipv6, it's used for just ipv4 as well, and munin-update could not access plain ipv4 addresses either.

[Pierce Lopez (pierce-lopez)]

Ok, I see what I did wrong - I typically install stuff in containers with --no-install-recommends to avoid a lot of junk. The "perl" package recommends netbase. So a normal install would have gotten it.

I guess this can be closed. If anything, maybe netbase should be a harder dependency of some perl stuff, which would be an ubuntu core project issue. It just took so much effort to figure this out :P

[Dan Watkins (oddbloke)]

Glad you worked out the issue!