github: simplify computation of the job's distro

We explicitly list the distro of Linux-based jobs, but it is equivalent
to the name of the image in almost all cases, except that colons are
replaced with dashes. Drop the redundant information and massage it in
our CI scripts, which is equivalent to how we do it in GitLab CI.

There are a couple of exceptions:

  - The "linux32" job, whose distro name is different than the image
    name. This is handled by adapting all sites to use the new name.

  - The "alpine" and "fedora" jobs, neither of which specify a tag for
    their image. This is handled by adding the "latest" tag.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.github/workflows/main.yml

@@ -275,7 +275,7 @@ jobs:
       CC: ${{matrix.vector.cc}}
       CC_PACKAGE: ${{matrix.vector.cc_package}}
       jobname: ${{matrix.vector.jobname}}
-      distro: ${{matrix.vector.pool}}
+      CI_JOB_IMAGE: ${{matrix.vector.pool}}
       TEST_OUTPUT_DIRECTORY: ${{github.workspace}}/t
     runs-on: ${{matrix.vector.pool}}
     steps:
@@ -316,63 +316,49 @@ jobs:
         - jobname: linux-sha256
           image: ubuntu:latest
           cc: clang
-          distro: ubuntu-latest
         - jobname: linux-reftable
           image: ubuntu:latest
           cc: clang
-          distro: ubuntu-latest
         - jobname: linux-gcc
           image: ubuntu:20.04
           cc: gcc
           cc_package: gcc-8
-          distro: ubuntu-20.04
         - jobname: linux-TEST-vars
           image: ubuntu:20.04
           cc: gcc
           cc_package: gcc-8
-          distro: ubuntu-20.04
         - jobname: linux-gcc-default
           image: ubuntu:latest
           cc: gcc
-          distro: ubuntu-latest
         - jobname: linux-leaks
           image: ubuntu:latest
           cc: gcc
-          distro: ubuntu-latest
         - jobname: linux-reftable-leaks
           image: ubuntu:latest
           cc: gcc
-          distro: ubuntu-latest
         - jobname: linux-asan-ubsan
           image: ubuntu:latest
           cc: clang
-          distro: ubuntu-latest
         - jobname: linux-meson
           image: ubuntu:latest
           cc: gcc
-          distro: ubuntu-latest
         - jobname: linux-musl
-          image: alpine
-          distro: alpine-latest
+          image: alpine:latest
         # Supported until 2025-04-02.
         - jobname: linux32
           image: i386/ubuntu:focal
-          distro: ubuntu32-20.04
         - jobname: pedantic
-          image: fedora
-          distro: fedora-latest
+          image: fedora:latest
         # A RHEL 8 compatible distro.  Supported until 2029-05-31.
         - jobname: almalinux-8
           image: almalinux:8
-          distro: almalinux-8
         # Supported until 2026-08-31.
         - jobname: debian-11
           image: debian:11
-          distro: debian-11
     env:
       jobname: ${{matrix.vector.jobname}}
-      distro: ${{matrix.vector.distro}}
       CC: ${{matrix.vector.cc}}
+      CI_JOB_IMAGE: ${{matrix.vector.image}}
     runs-on: ubuntu-latest
     container: ${{matrix.vector.image}}
     steps:

ci/install-dependencies.sh

@@ -33,7 +33,7 @@ fedora-*|almalinux-*)
 	dnf -yq update >/dev/null &&
 	dnf -yq install shadow-utils sudo make gcc findutils diffutils perl python3 gettext zlib-devel expat-devel openssl-devel curl-devel pcre2-devel >/dev/null
 	;;
-ubuntu-*|ubuntu32-*|debian-*)
+ubuntu-*|i386/ubuntu-*|debian-*)
 	# Required so that apt doesn't wait for user input on certain packages.
 	export DEBIAN_FRONTEND=noninteractive
 
@@ -42,7 +42,7 @@ ubuntu-*|ubuntu32-*|debian-*)
 		SVN='libsvn-perl subversion'
 		LANGUAGES='language-pack-is'
 		;;
-	ubuntu32-*)
+	i386/ubuntu-*)
 		SVN=
 		LANGUAGES='language-pack-is'
 		;;

ci/lib.sh

@@ -246,6 +246,8 @@ then
 
 	GIT_TEST_OPTS="--github-workflow-markup"
 	JOBS=10
+
+	distro=$(echo "$CI_JOB_IMAGE" | tr : -)
 elif test true = "$GITLAB_CI"
 then
 	CI_TYPE=gitlab-ci