examples: add 'rhel9' and 'rawhide' bls examples

Add two new OS images to CI:

 - `rhel9`: to test that  feature flag `rhel9` is working correctly
 - `rawhide`: with a 6.15 pre-release kernel, requiring no features

This helps round out the verification that our new mount code behaves
correctly in all of the situations that it claims to.

Signed-off-by: Allison Karlitskaya <allison.karlitskaya@redhat.com>

Author: allisonkarlitskaya

.github/workflows/examples.yml

@@ -18,6 +18,8 @@ jobs:
         example:
           - { dir: 'bls', os: 'arch' }
           - { dir: 'bls', os: 'fedora' }
+          - { dir: 'bls', os: 'rawhide' }
+          - { dir: 'bls', os: 'rhel9' }
           - { dir: 'bls', os: 'ubuntu' }
           - { dir: 'uki', os: 'arch' }
           - { dir: 'uki', os: 'fedora' }

examples/bls/Containerfile.rawhide

@@ -0,0 +1,14 @@
+FROM fedora:rawhide
+COPY extra /
+COPY cfsctl /usr/bin
+RUN --mount=type=cache,target=/var/cache/libdnf5 <<EOF
+    set -eux
+    dnf --setopt keepcache=1 install --allowerasing -y systemd util-linux skopeo composefs strace dosfstools kernel openssh-server
+    systemctl enable systemd-networkd
+    passwd -d root
+    mkdir /sysroot
+    mkdir /composefs-meta
+    mv /boot /composefs-meta
+    mkdir /boot
+EOF
+RUN true  # hack to get an extra layer

examples/bls/Containerfile.rhel9

@@ -0,0 +1,19 @@
+# FROM docker.io/redhat/ubi9  missing: dosfstools, kernel
+FROM quay.io/centos/centos:9
+COPY extra /
+COPY cfsctl /usr/bin
+RUN --mount=type=cache,target=/var/cache/dnf <<EOF
+    set -eux
+    mkdir -p /etc/kernel
+    touch /etc/kernel/cmdline
+    echo layout=bls | tee /etc/kernel/install.conf
+    dnf --setopt keepcache=1 install --allowerasing -y \
+        systemd util-linux skopeo composefs strace dosfstools kernel openssh-server passwd NetworkManager
+    systemctl enable tmp.mount
+    passwd -d root
+    mkdir /sysroot
+    mkdir /composefs-meta
+    mv /boot /composefs-meta
+    mkdir /boot
+EOF
+RUN true  # hack to get an extra layer

examples/bls/build

@@ -16,11 +16,17 @@ case "${os}" in
         containerfile='Containerfile.arch'
         features='--features=pre-6.15'
         ;;
+    rhel9)
+        containerfile='Containerfile.rhel9'
+        features='--features=rhel9'
         ;;
     ubuntu)
         containerfile='Containerfile.ubuntu'
         features='--features=pre-6.15'
         ;;
+    rawhide)
+        containerfile='Containerfile.rawhide'
+        features='--no-default-features'
         ;;
     *)
         echo "*** unknown variant ${os}"