ci: migrate actions runners off ubuntu 20.04

.github/workflows/ci.yaml

@@ -10,7 +10,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     strategy:
       fail-fast: false
       matrix:
@@ -20,10 +20,12 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: run
-      run: sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make check"
+      run: |
+        sudo ./scripts/github-ci-lxd-setup.sh
+        sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make check"
 
   lint:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     strategy:
       fail-fast: false
       matrix:
@@ -33,18 +35,20 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: lint
-      run: sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make lint"
+      run: |
+        sudo ./scripts/github-ci-lxd-setup.sh
+        sudo ./scripts/test-in-lxd.sh ${{ matrix.image }} "make lint"
 
   format-black:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
       - uses: psf/black@stable
         with:
           version: "~= 23.0"
           src: "console_conf subiquity subiquitycore"
   format-isort:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
       - uses: isort/isort-action@v1
@@ -54,7 +58,7 @@ jobs:
   static-typing:
     # In this job, we compare the output of mypy before and after the PR.
     if: github.event_name == 'pull_request'
-    runs-on: ubuntu-22.04  # minimimum 22.04 for python3-typeshed
+    runs-on: ubuntu-24.04
     steps:
       - name: Install mypy and typeshed
         run: sudo apt-get install -y python3-mypy python3-typeshed

.github/workflows/cla-check.yaml

@@ -4,7 +4,7 @@ on: [pull_request]
 
 jobs:
   cla-check:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Check if CLA signed
         uses: canonical/has-signed-canonical-cla@v2

.github/workflows/snap.yaml

@@ -10,7 +10,7 @@ on:
 
 jobs:
   snap-build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-24.04
     steps:
     - uses: actions/checkout@v4
     - uses: canonical/action-build@v1

scripts/github-ci-lxd-setup.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+set -eux
+
+# The purpose of this script is to separate out the actions needed to setup
+# LXD on the GitHub Actions CI runners from the actual test setup and 
+# execution. This way, test scripts can be mostly run locally without making
+# too many changes to the local system.
+
+# The runner images don't have lxd enabled by default.
+lxd init --auto
+
+# If the runner image uses docker, then work around a known connectivity issue
+# when using lxd and docker at the same time.
+# https://discuss.linuxcontainers.org/t/containers-do-not-have-outgoing-internet-access/10844/7
+# https://documentation.ubuntu.com/lxd/en/latest/howto/network_bridge_firewalld/#prevent-connectivity-issues-with-lxd-and-docker
+if [ "active" == "$(systemctl is-active docker)" ]
+then
+    iptables  -I DOCKER-USER -i lxdbr0 -j ACCEPT
+    iptables  -I DOCKER-USER -o lxdbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+    # GitHub doesn't use IPV6 (yet?)
+    # ip6tables -I DOCKER-USER -i lxdbr0 -j ACCEPT
+    # ip6tables -I DOCKER-USER -o lxdbr0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+fi

scripts/test-in-lxd.sh

@@ -19,7 +19,6 @@ IMAGE=$1
 TEST_CMD=$2
 TESTER=subiquity-${IMAGE##*:}
 
-lxd init --auto
 
 if [ -z "$(lxc list -f csv -c n ^${TESTER}\$)" ]
 then