osbuild: use bootc install to deploy the container

Instead of deploying the container to the tree then copy all the contents
to the disk image, use bootc to directly manage the installation to the
target filesystems.

Right now this requires to use the image as the buildroot so this
requires python (for osbuild). This is tracked in [1].
As we have python in rawhide now I duplicated the manifest and added a
switch in the osbuild wrapper script.

We can keep the manifest duplicated until we are confident to roll this
to all streams.

[1] bootc-dev/bootc#1410

Requires:
bootc-dev/bootc#1460
bootc-dev/bootc#1451
osbuild/osbuild#2149
osbuild/osbuild#2152

All of which have landed in osbuild-159 and bootc 1.6

Author: jbtrystram

src/cmd-osbuild

@@ -409,14 +409,22 @@ main() {
         cmd="runvm_with_cache"
     fi
 
+    # Use the bootc install to-filesystem manifest if applicable
+    bootc_suffix=""
+    if should_use_bootc_install; then
+        bootc_suffix=".bootc"
+    fi
+
+    manifest_path="/usr/lib/coreos-assembler/osbuild-manifests/coreos.osbuild.${basearch}${bootc_suffix}.mpp.yaml"
+
     # To get a shell in the osbuild supermin VM uncomment this.
     # osbuild can then be started with `bash tmp/build.<artifact>/cmd.sh`
     # See comment about checkpoints in runvm-osbuild
     # RUNVM_SHELL=1 \
-    $cmd -- /usr/lib/coreos-assembler/runvm-osbuild                                         \
-                --config "${runvm_osbuild_config_json}"                                                 \
-                --mpp "/usr/lib/coreos-assembler/osbuild-manifests/coreos.osbuild.${basearch}.mpp.yaml" \
-                --outdir "${outdir}"                                                                    \
+    $cmd -- /usr/lib/coreos-assembler/runvm-osbuild                                                                          \
+                --config "${runvm_osbuild_config_json}"                                                                      \
+                --mpp "${manifest_path}"                                                                                     \
+                --outdir "${outdir}"                                                                                         \
                 --platforms "$(IFS=,; echo "${platforms[*]}")"
 
     for platform in "${platforms[@]}"; do

src/cmdlib.sh

@@ -148,10 +148,17 @@ yaml2json() {
     python3 -c 'import sys, json, yaml; json.dump(yaml.safe_load(sys.stdin), sys.stdout, sort_keys=True)' < "$1" > "$2"
 }
 
-should_build_with_buildah() {
-    local variant manifest
-    if [ -n "${COSA_BUILD_WITH_BUILDAH:-}" ]; then
-        if [ "${COSA_BUILD_WITH_BUILDAH:-}" = 1 ]; then
+# Common helper to check for features that can be enabled via an env var or
+# in the manifest metadata.
+_should_enable_feature() {
+    local env_var_name=$1
+    local metadata_key=$2
+    local env_var_value
+    # Indirect expansion
+    env_var_value=${!env_var_name:-}
+
+    if [ -n "${env_var_value}" ]; then
+        if [ "${env_var_value}" = 1 ]; then
             return 0
         else
             return 1
@@ -164,12 +171,20 @@ should_build_with_buildah() {
     else
         manifest="src/config/manifest.yaml"
     fi
-    if [ "$(yq .metadata.build_with_buildah "${manifest}")" = true ]; then
+    if [ "$(yq ".metadata.${metadata_key}" "${manifest}")" = true ]; then
         return 0
     fi
     return 1
 }
 
+should_use_bootc_install() {
+    _should_enable_feature "COSA_OSBUILD_USE_BOOTC_INSTALL" "use_bootc_install"
+}
+
+should_build_with_buildah() {
+    _should_enable_feature "COSA_BUILD_WITH_BUILDAH" "build_with_buildah"
+}
+
 prepare_build() {
     preflight
     preflight_kvm