ci: Add build test for Ubuntu Focal

This is to ensure the software continues to build on (somewhat old)
"Ubuntu Focal"-based distros. At the moment, package "libfsverity-dev"
is not available on that distro, so make its installation optional.

Signed-off-by: Rogerio Guerra Borin <[email protected]>

.github/workflows/test.yaml

@@ -29,6 +29,23 @@ jobs:
         with:
           name: composefs.tar
           path: composefs.tar
+  build-baseline:
+    runs-on: ubuntu-latest
+    name: "Build on Ubuntu Focal"
+    container: ubuntu:focal
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Install dependencies
+        run: |
+          apt-get update -y
+          ALLOW_MISSING="libfsverity-dev" ./hacking/installdeps.sh
+      - name: Configure
+        run: |
+          ./autogen.sh
+          ./configure --prefix=/usr --sysconfdir=/etc --libdir=/usr/lib/$(dpkg-architecture -qDEB_HOST_MULTIARCH) CFLAGS='-Wall -Werror'
+      - name: Build
+        run: make -j $(nproc) CFLAGS='-fsanitize=address -fsanitize=undefined'
   build-unit-cross:
     runs-on: ubuntu-latest
     name: Build on ${{ matrix.arch }}

hacking/installdeps.sh

@@ -1,4 +1,40 @@
 #!/bin/bash
 set -xeuo pipefail
 export DEBIAN_FRONTEND=noninteractive
-apt-get install -y automake libtool autoconf autotools-dev git make gcc libssl-dev libfsverity-dev pkg-config libfuse3-dev python3 libcap2-bin
+
+PACKAGES=" \
+    automake \
+    libtool \
+    autoconf \
+    autotools-dev \
+    git \
+    make \
+    gcc \
+    libssl-dev \
+    libfsverity-dev \
+    pkg-config \
+    libfuse3-dev \
+    python3 \
+    libcap2-bin \
+"
+
+# Split required and optional packages based on input variable ALLOW_MISSING:
+PACKAGES_REQUIRED=""
+PACKAGES_OPTIONAL=""
+
+for pkg in $PACKAGES; do
+    if [[ " ${ALLOW_MISSING:-} " == *" ${pkg} "* ]]; then
+	PACKAGES_OPTIONAL+=" ${pkg}"
+    else
+	PACKAGES_REQUIRED+=" ${pkg}"
+    fi
+done
+
+# Install packages:
+if [ -n "${PACKAGES_REQUIRED}" ]; then
+    apt-get install -y $PACKAGES_REQUIRED
+fi
+
+if [ -n "${PACKAGES_OPTIONAL}" ]; then
+    apt-get install -y --ignore-missing $PACKAGES_OPTIONAL || true
+fi