Are the protobuf things needed for all off runc, criu and docker ?

(Also, are they needed at runtime or only ad build-time)?

Thanks for the feedback, not all of those packages are needed at runtime.
Actually, criu is linked only with librt, libprotobuf-c, libdl, libnl-3 and libnet.
Without these installed at runtime it fails, for example, with:

$ criu --version
criu: error while loading shared libraries: libprotobuf-c.so.1: cannot open shared object file: No such file or directory

I will update the commit to install only the necessary packages.

Actually, instead of installing these packages at runtime, it would be better to only copy the required files (i.e. libnet.so.1, libnl-3.so.200, libprotobuf-c.so.1). I will update the commit accordingly.

it would be better to only copy the required files

@rst0git it might seem like a good idea now, but some time later than libnl-3.so.200 will become libnl-3.so.201 and everything will break, we are going to regret it (to say at least).

One other thing, if you're using a package manager you're sure dependencies are satisfied (say if libprotobuf will suddely require libxyz, package manager will take care of it), and if you're doing it manually, it's a time bomb.

So, please revert to installing needed deps during runtime.

Done.

Curious, IIUC, this will limit the number of jobs at once (as the default is "infinite"), correct?

  -j [N], --jobs[=N]          Allow N jobs at once; infinite jobs with no arg.

Yes, the default value, "infinite", can quickly take over all available memory on a large build. Although criu is not very large, -j $(nproc) works well, and it is the approach that is used in the Dockerfile template for travis-ci.

Thanks for explaining 👍