[squid-dev] RFC: Semaphore CI to GitHub Actions migration

[Alex Rousskov]

Hello,

     I plan to gradually turn Semaphore CI testing off and make GitHub 
Actions required. We should not babysit the same tests in two setups. 
Here is the current status of CI tests with regard to Semaphore and 
GitHub Actions together with the corresponding planned actions:

1. Functionality tests: Essentially the same set of tests. Semaphore CI 
has one extra/old test but it is disabled for master/v6 code. The 
proxy-collapsed-forwarding test often fails on Semaphore, requiring a 
manual restart of all tests. The busy-restart test usually fails on 
GitHub Actions, but those failures are currently ignored.

Plan: I will leave the busy-restart test running on Semaphore CI until 
we find a way to make it stable in GitHub Actions environment. I will 
turn off the other Semaphore CI functionality tests and make the GitHub 
Actions ones required.


2. Source maintenance tests: The same set of tests. GitHub Actions have 
the right Astyle version, so the formatting test actually works on 
GitHub (but its results are currently ignored on both platforms).

Plan: I will turn off Semaphore CI source maintenance tests and make the 
GitHub Actions ones required instead. Formatting test results will still 
be ignored (that is a separate decision/change/action out of this thread 
scope; let's not discuss it here).


3. Build tests: Semaphore CI uses Ubuntu 14.04. GitHub Actions uses 
Ubuntu 22.04. Semaphore CI has fewer build dependencies installed. 
GitHub Actions do not provide Ubuntu 14.04 runners[1].

Plan: I will keep Semaphore CI build tests and make the GitHub Actions 
tests required. When Semaphore CI build tests start failing (e.g., 
because dependency repositories stop working "as is"), or when we stop 
supporting that old environment, I will disable those tests.


If you have any objections or better ideas about gradually moving away 
from Semaphore CI, please discuss.


Thank you,

Alex.

[1]  GitHub provides Ubuntu 18.04 runners, but they are deprecated, will 
purposefully _fail_ according to GitHub schedule, and will be removed in 
December. We should not use them. Details at 
https://github.blog/changelog/2022-08-09-github-actions-the-ubuntu-18-04-actions-runner-image-is-being-deprecated-and-will-be-removed-by-12-1-22/