Introduce a Nix flake for CRIU development

[snprajwal]

CRIU currently requires a decent number of dependencies in order to build from source. I also suspect that we are dependent on specific versions of certain dependencies in order to build correctly or support some features. Introducing a Nix flake will allow developers to spin up a dev env using nix develop, saving them the trouble of manually dealing with dependency installation across distros. It'll also prevent us from polluting the global package set on the machine in case we need to jump back and fix a regression that needs an older version of a dependency.

This would simply require adding a flake.nix file with the appropriate configuration to successfully build CRIU.

[adrianreber]

Never used nix. Cannot say anything about it. But CRIU does not really depend on specific versions of its dependencies.

[avagin]

It is unclear what problem does it solve. We have dockerfile-s to build criu for different linux distributions. I don't see any issues with them. Feel free to reopen this issue.

[snprajwal]

CRIU build dependencies: gcc make protobuf protobuf-c protobuf-c-devel protobuf-compiler protobuf-devel protobuf-python
CRIU optional build dependencies: pkg-config python-ipaddress libbsd-devel iproute2 nftables libcap-devel libnet-devel libaio-devel gnutls-devel python3-future libdrm-devel

The second set of packages also vary across package managers (RPM and DEB package names are somewhat different). Having a Nix flake would make it easier to manage this, and also enable us to trivially spin up dev envs with different versions of these packages in case we have regressions, adding some new feature, etc.

We can leave the issue closed, since it's more of a "nice to have" brownie point thing. But I'll get this done, I feel it'll be useful.

[github-actions]

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