t3c ATS RPM: Enable software collections environment before building OpenSSL

[zrhoffman]

This PR gets building the Cache Config Integration Tests's configuration for a CentOS 7 ATS RPM to work again by enabling the newer GCC version before trying to build OpenSSL and using the OS_DISTRO and OS_VERSION values set when the Docker image is built.

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Which Traffic Control components are affected by this PR?

• Traffic Control Cache Config (t3c, formerly ORT) - integration tests ATS RPM build configuration

What is the best way to verify this PR?

Verify that building the ATS RPM for CentOS 7 passes:

export OS_DISTRO=centos OS_VERSION=7
cd cache-config/testing/docker
docker-compose -f docker-compose-ats-build.yml build
docker-compose -f docker-compose-ats-build.yml up

PR submission checklist

• This PR has tests
• This PR has documentation
• This PR has a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[ocket8888]

Should we change the t3c tests to a matrix of the two OSes ? Right now this may fix it, but the default is to use Rocky 8 so the GHAs don't tell me if it's fixed.

[zrhoffman]

Apache asks projects not to use the matrix execution strategy on PRs, due to the concurrent job limit for the whole Apache org:

My proposal is to create a GitHub Action that will allow to run only a
subset of "matrix" test for PRs that are not yet approved by committers.

So we could do matrix on the master branch as long as we don't do it on PRs.

[ocket8888]

Well a matrix would be easiest, but if we shouldn't do that should it at least test them both sequentially?

[zrhoffman]

That would probably be okay

[zrhoffman]

How would you do it sequentially, though, without having the job be twice as long?

[ocket8888]

You wouldn't, which is what I mean about matrix being the easiest way.

[zrhoffman]

Rocky Linux 8 is already well-tested in the T3C Integration Tests, CDN-in-a-Box CI, and TC Health Client Integration Tests workflows. How about a CentOS 7-only workflow that builds the ATS RPM whenever files in that directory (or the dockerfile) are changed?

Then we wouldn't need matrix.

[ocket8888]

Sure, that's fine by me.