[STAL-2781] Build release Linux binary on Ubuntu 20.04

[jasonforal]

What problem are you trying to solve?

We currently compile our Linux release binaries on GitHub's ubuntu-latest runner, which resolves to ubuntu 24.04. Because 24.04 uses a newer version of glibc, it compiles binaries that expect more recent versions of glibc (currently, v8 expects pthread_getattr_np@GLIBC_2.32). This leads to an error when trying to run the binary on older versions of Linux (specifically Ubuntu 20.04, which ships with glibc 2.31)

What is your solution?

Building on Ubuntu 20.04 generates a binary that now expects glibc 2.2.5:

❯ greadelf -a datadog-static-analyzer-server | grep pthread_getattr_np
000003efe688  011700000006 R_X86_64_GLOB_DAT 0000000000000000 pthread_getattr_np@GLIBC_2.2.5 + 0

And thus the binaries now work on Ubuntu 20.04.

You can confirm that this modification to the release workflow functions correctly by looking at a pre-release that I just generated to test it:

We need to add an extra step to set up the container, as the base image is missing the packages that GitHub installs by default on a non-containerized runner (curl, gh, etc).

Alternatives considered

What the reviewer should know

• I only modified the release.yml to build on Ubuntu 20.04 -- all of the integration tests will still build/run on ubuntu-latest (currently 24.04). Assuming glibc doesn't have forward-compatibility issues, this setup is fine.
• glibc has backwards compatibility for the APIs we're using, so this runs on 22.04 (glibc 2.35), 24.04 (glibc 2.39)

[jasonforal]

Special thanks to @robertohuertasm for debugging this and identifying the solution

[robertohuertasm]

Thank you @jasonforal for your nice words ❤️ and for your thorough work on this issue 🙌🏻 . It's always a pleasure to collaborate with you!

[jasonforal]

Yes, for the APIs we're using, newer versions of glibc have backwards-compatibility. So it works on 22.04, 24.04, etc.