osbuild: add support for metal platform

This reworks the coreos.osbuild.mpp.yaml to use the new kernel-cmdline.bls-append
stage [1], enabling us to share earlier stages among the platform specific pipelines.
We have renamed the pipeline stages to be more appropriate. Now we have

- tree
    - the filesystem tree
- raw-image
    - builds on "tree"
    - a raw disk image with nothing platform specific, like kernel arguments
- raw-metal-image
    - builds on "raw-image"
    - adds kernel arguments specific to `metal` platform
- raw-qemu-image
    - builds on "raw-image"
    - adds kernel arguments specific to `qemu` platform
- metal
    - builds on "raw-metal-image"
    - copies out raw image file from "raw-metal-image" stage
    - no other modifications needed
- qemu
    - builds on "raw-qemu-image"
    - converts raw image file from "raw-qemu-image" into a qcow2

We have also modified cmd-buildextend-metal to support calling
runvm-osbuild for either metal or qemu platform images and also added
support for running with the cache qcow2. The cache qcow will allow us
to call osbuild multiple times, with later invocations building on work
done in previous invocations. For example if we checkpiont the `tree`
and `raw-image` stages (as depicted above) then when we call osbuild to
build the `metal` image it won't have to do the work for that. The
benefits of this will compound when we start to build more disk images
in this way.

[1] osbuild/osbuild#1429

src/cmd-buildextend-metal

@@ -262,9 +262,15 @@ cat "${image_json}" image-dynamic.json | jq -s add > image-for-disk.json
 platforms_json="${workdir}/tmp/platforms.json"
 yaml2json "${configdir}/platforms.yaml" "${platforms_json}"
 
-if [ "${image_type}" == "qemu" ] && [ "${COSA_USE_OSBUILD:-}" != "" ]; then
-    runvm -- /usr/lib/coreos-assembler/runvm-osbuild              \
-                "${ostree_repo}" "${ref}"                         \
+# Currently we only support OSBuild for qemu and metal disk images
+if [ "${image_type}" == "qemu" ] || [ "${image_type}" == "metal" ]; then
+    OSBUILD_SUPPORTED=1
+fi
+
+# Run with OSBuild if it's supported and requested, otherwise use create_disk
+if [ "${OSBUILD_SUPPORTED:-}" != "" ] && [ "${COSA_USE_OSBUILD:-}" != "" ]; then
+    runvm_with_cache -- /usr/lib/coreos-assembler/runvm-osbuild   \
+                "${ostree_repo}" "${ref}" ${image_type}           \
                 /usr/lib/coreos-assembler/coreos.osbuild.mpp.yaml \
                 "${path}.tmp"
 else

src/coreos.osbuild.mpp.yaml

@@ -1,6 +1,6 @@
 version: '2'
 mpp-vars:
-  release: 38
+  filename: $filename
 mpp-define-image:
   id: image
   #10G
@@ -28,7 +28,7 @@ mpp-define-image:
         type: 0FC63DAF-8483-4772-8E79-3D69D8477DE4
         uuid: CA7D7CCB-63ED-4C53-861C-1742536059CC
 pipelines:
-  - name: image-tree
+  - name: tree
     source-epoch: 1659397331
     stages:
       - type: org.osbuild.ostree.init-fs
@@ -57,9 +57,6 @@ pipelines:
             - /boot/efi
           kernel_opts:
             - rw
-            - console=tty0
-            - console=ttyS0
-            - ignition.platform.id=qemu
             - '$ignition_firstboot'
         inputs:
           commits:
@@ -88,7 +85,7 @@ pipelines:
           write_defaults: false
           greenboot: false
           ignition: true
-  - name: image
+  - name: raw-image
     stages:
       - type: org.osbuild.truncate
         options:
@@ -151,7 +148,7 @@ pipelines:
             type: org.osbuild.tree
             origin: org.osbuild.pipeline
             references:
-              - name:image-tree
+              - name:tree
         options:
           paths:
             - from: input://tree/
@@ -211,18 +208,99 @@ pipelines:
             number:
               mpp-format-int: '{image.layout[''boot''].index}'
             path: /grub2
-  - name: qcow2
+  - name: raw-metal-image
+    stages:
+      - type: org.osbuild.copy
+        inputs:
+          tree:
+            type: org.osbuild.tree
+            origin: org.osbuild.pipeline
+            references:
+              - name:raw-image
+        options:
+          paths:
+            - from: input://tree/disk.img
+              to: tree:///disk.img
+      - type: org.osbuild.kernel-cmdline.bls-append
+        options:
+          bootpath: mount:///
+          kernel_opts:
+            - ignition.platform.id=metal
+        devices:
+          boot:
+            type: org.osbuild.loopback
+            options:
+              filename: disk.img
+              start:
+                mpp-format-int: '{image.layout[''boot''].start}'
+              size:
+                mpp-format-int: '{image.layout[''boot''].size}'
+        mounts:
+          - name: boot
+            type: org.osbuild.ext4
+            source: boot
+            target: /
+  - name: raw-qemu-image
+    stages:
+      - type: org.osbuild.copy
+        inputs:
+          tree:
+            type: org.osbuild.tree
+            origin: org.osbuild.pipeline
+            references:
+              - name:raw-image
+        options:
+          paths:
+            - from: input://tree/disk.img
+              to: tree:///disk.img
+      - type: org.osbuild.kernel-cmdline.bls-append
+        options:
+          bootpath: mount:///
+          kernel_opts:
+            - console=tty0
+            - console=ttyS0,115200n8
+            - ignition.platform.id=qemu
+        devices:
+          boot:
+            type: org.osbuild.loopback
+            options:
+              filename: disk.img
+              start:
+                mpp-format-int: '{image.layout[''boot''].start}'
+              size:
+                mpp-format-int: '{image.layout[''boot''].size}'
+        mounts:
+          - name: boot
+            type: org.osbuild.ext4
+            source: boot
+            target: /
+  - name: metal
+    stages:
+      - type: org.osbuild.copy
+        inputs:
+          tree:
+            type: org.osbuild.tree
+            origin: org.osbuild.pipeline
+            references:
+              - name:raw-metal-image
+        options:
+          paths:
+            - from: input://tree/disk.img
+              to:
+                mpp-format-string: 'tree:///{filename}'
+  - name: qemu
     stages:
       - type: org.osbuild.qemu
         inputs:
           image:
             type: org.osbuild.files
             origin: org.osbuild.pipeline
             references:
-              name:image:
+              name:raw-qemu-image:
                 file: disk.img
         options:
-          filename: disk.qcow2
+          filename:
+            mpp-format-string: '{filename}'
           format:
             type: qcow2
             compat: '1.1'

src/runvm-osbuild

@@ -3,28 +3,36 @@ set -eux -o pipefail
 
 repo=$1
 ref=$2
-mppyaml=$3
-path=$4
+platform=$3
+mppyaml=$4
+path=$5
+filename=$(basename "$path")
 
 # Since it doesn't exist create loop-control
 mknod /dev/loop-control c 10 237
 
-# get away from the virtiofs share because the xattrs that
-# are written out by the ostree deploy will cause SELinux denials.
-mkdir /root/osbuild && cd /root/osbuild
+# Tell osbuild to write out artifacts into a file in the root
+# filesystem of the supermin VM, which is ephemeral.
+mkdir /var/osbuild
+outdir=/var/osbuild/out
 
 # Run through the preprocessor
 osbuild-mpp                         \
     -D ref=\""${ref}"\"             \
     -D repourl=\""file://${repo}"\" \
+    -D filename=\""${filename}"\"   \
     "${mppyaml}"                    \
     processed.json
 
 # Build the image
-osbuild --store store/      \
-    --output-directory out/ \
-    --export qcow2 processed.json
+osbuild \
+    --out "$outdir"            \
+    --store cache/osbuild/store/ \
+    --cache-max-size 9GiB        \
+    --checkpoint tree            \
+    --checkpoint raw-image       \
+    --export "$platform" processed.json
 
 
 # Copy it out to the specified location
-cp out/qcow2/disk.qcow2 "${path}"
+cp "${outdir}/${platform}/${filename}" "${path}"