ci: let ubuntu version be configurable

.github/integration-test.py

@@ -4,15 +4,16 @@ import subprocess
 import os
 
 
-def build_systemd_image(image_name, source_path):
+def build_systemd_image(image_name, source_path, build_args=None):
     """
     Build docker image with systemd at source_path.
 
     Built image is tagged with image_name
     """
-    subprocess.check_call([
-        'docker', 'build', '-t', image_name, source_path
-    ])
+    cmd = ['docker', 'build', '-t', image_name, source_path]
+    if build_args:
+        cmd.extend([f"--build-arg={ba}" for ba in build_args])
+    subprocess.check_call(cmd)
 
 
 def run_systemd_image(image_name, container_name, bootstrap_pip_spec):
@@ -138,13 +139,21 @@ def main():
     argparser = argparse.ArgumentParser()
     subparsers = argparser.add_subparsers(dest='action')
 
-    subparsers.add_parser('build-image')
+    build_image_parser = subparsers.add_parser('build-image')
+    build_image_parser.add_argument(
+        "--build-arg",
+        action="append",
+        dest="build_args",
+    )
+
     subparsers.add_parser('stop-container').add_argument(
         'container_name'
     )
+
     subparsers.add_parser('start-container').add_argument(
         'container_name'
     )
+
     run_parser = subparsers.add_parser('run')
     run_parser.add_argument('container_name')
     run_parser.add_argument('command')
@@ -181,7 +190,7 @@ def main():
     elif args.action == 'stop-container':
         stop_container(args.container_name)
     elif args.action == 'build-image':
-        build_systemd_image(image_name, 'integration-tests')
+        build_systemd_image(image_name, 'integration-tests', args.build_args)
 
 
 if __name__ == '__main__':

.github/workflows/integration-test.yaml

@@ -60,22 +60,22 @@ jobs:
         env:
           matrix_include_pre_filter: |
             - name: "Int. tests: Ubuntu 18.04, Py 3.6"
-              runs_on: ubuntu-18.04
+              ubuntu_version: 18.04
               python_version: 3.6
               extra_flags: ""
             - name: "Int. tests: Ubuntu 20.04, Py 3.9"
-              runs_on: ubuntu-20.04
+              ubuntu_version: 20.04
               python_version: 3.9
               extra_flags: ""
             - name: "Int. tests: Ubuntu 20.04, Py 3.9, --upgrade"
-              runs_on: ubuntu-20.04
+              ubuntu_version: 20.04
               python_version: 3.9
               extra_flags: --upgrade
               dont_run_on_ref: refs/heads/master
 
   integration-tests:
     needs: decide-on-test-jobs-to-run
-    runs-on: ${{ matrix.runs_on }}
+    runs-on: ubuntu-${{ matrix.ubuntu_version }}
 
     name: ${{ matrix.name }}
     strategy:
@@ -95,7 +95,7 @@ jobs:
 
       - name: Build systemd image
         run: |
-          .github/integration-test.py build-image
+          .github/integration-test.py build-image --build-arg ubuntu_version=${{ matrix.ubuntu_version }}
 
       - name: Run bootstrap checks
         run: |