patch, 3 partsgitlab-ci: switch from Ubuntu 16.04 to 20.04

In many cases, we're not testing some of the older Linux distributions that we support. However, we _are_ testing some old Linux distributions that we _don't_ support. That means that it's presently difficult for us to make sure our code works on all the systems we want it to and that we're not accidentally requiring newer versions of dependencies than we claim to support.

The first patch removes Ubuntu 16.04, which is out of regular LTS support. The second removes the clause in the CI job for that OS. The third adds several new CI jobs to make sure we're adequately supporting older Debian and RHEL-compatible distros, and documents the dates at which they lose support (so it's easy to know if we need to update them).

brian m. carlson (3):
  gitlab-ci: switch from Ubuntu 16.04 to 20.04
  ci: remove clause for Ubuntu 16.04
  Add additional CI jobs to avoid accidental breakage

 .github/workflows/main.yml |  9 +++++++++
 .gitlab-ci.yml             |  2 +-
 ci/install-dependencies.sh | 19 ++++++++++---------
 3 files changed, 20 insertions(+), 10 deletions(-)

Ubuntu 16.04 is past its normal LTS lifespan, so let's switch to Ubuntu 20.04 instead, which is the latest regular LTS version.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

In general, we'd like to make sure Git works on the LTS versions of major Linux distributions. To do that, let's add CI jobs for the oldest regular (non-extended) LTS versions of the major distributions: Ubuntu 20.04, Debian 11, and RHEL 8. Because RHEL isn't available to the public at no charge, use AlmaLinux, which is binary compatible with it.

Note that Debian does not offer the language-pack packages, but suitable locale support can be installed with the locales-all package. Otherwise, use the set of installation instructions which exist and are most similar to the existing supported distros.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 .github/workflows/main.yml |  9 +++++++++
 ci/install-dependencies.sh | 14 ++++++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

We're no longer testing this version and it's well beyond regular LTS support now, so remove the stanza for it from the case statement in our CI code.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 ci/install-dependencies.sh | 5 -----
 1 file changed, 5 deletions(-)

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

Something like "we replaced it with 20.04 which does not need the corresponding special casing" would be necessary to explain why this is a good change, as opposed to an equally plausible-looking patch that replaces 16.04 with 20.04 and otherwise keeps the "stanza".

On 2024-11-01 at 00:34:14, Junio C Hamano wrote:

Sure, I can mention that in v2.

Junio C Hamano <gitster@pobox.com> writes:

Ah, I take it back (or atleast a half of it).  

We have been already using 20.04 on the .github/ side, and 1/3 removed only from .gitlab-ci removing the last user of 16.04, so presumably this has already tested well for 20.04 and there is no need to add "corresponding special casing".

I'll keep reading the list backwards, this time resisting my temptation to utter nonsense without thinking much, attempting to catch up.

Thanks.

On Thu, Oct 31, 2024 at 11:49:31PM +0000, brian m. carlson wrote:

The GitLab CI-related changes all look good to me, thanks! The GitHub ones do, too, but I feel less qualified to comment on them.

Patrick