wip 31ignition-ostree

For redeploying the rootfs

dracut/30ignition/coreos-gpt-setup@.service

@@ -8,7 +8,7 @@ Requires=%i.device
 After=%i.device
 # Run before services that use device nodes, preventing them from racing
 # with udev activity generated by sgdisk
-Before=ignition-setup-base.service ignition-setup-user.service ignition-disks.service
+Before=ignition-setup-base.service ignition-setup-user.service ignition-ostree-rootfs-save.service ignition-disks.service
 
 [Service]
 Type=oneshot

dracut/31ignition-ostree/ignition-ostree-dracut-rootfs.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+set -euo pipefail
+
+rootmnt=/sysroot
+tmproot=/run/ignition-ostree-rootfs
+
+case "${1:-}" in
+    detect)
+        # This is obviously crude; perhaps in the future we could change ignition's `fetch`
+        # stage to write out a file if the rootfs is being replaced or so.  But eh, it
+        # works for now.
+        has_rootfs=$(jq '.storage?.filesystems? // [] | map(select(.label == "root")) | length' < /run/ignition.json)
+        if [ "${has_rootfs}" = "0" ]; then
+            exit 0
+        fi
+        echo "Detected rootfs replacement in fetched Ignition config: /run/ignition.json"
+        mkdir "${tmproot}"
+        ;;
+    save)
+        # This one is in a private mount namespace since we're not "offically" mounting
+        mount /dev/disk/by-label/root $rootmnt
+        echo "Moving rootfs to RAM..."
+        # OSTree added the immutable bit on the deployment root, and
+        # cosa's create_disk added it to the rootfs
+        chattr -i ${rootmnt} ${rootmnt}/ostree/deploy/*/deploy/*.0
+        for x in boot ostree; do
+            # TODO; copy instead of mv to avoid writes, since we're just
+            # about to blow away the whole FS anyways?
+            mv -Tn ${rootmnt}/${x} ${tmproot}/${x}
+        done
+        umount ${rootmnt}
+        echo "Moved rootfs to RAM, pending redeployment: ${tmproot}"
+        ;;
+    restore)
+        # This one is in a private mount namespace since we're not "offically" mounting
+        mount /dev/disk/by-label/root $rootmnt
+        echo "Restoring rootfs from RAM..."
+        for x in boot ostree; do
+            mv -Tn ${tmproot}/${x} ${rootmnt}/${x}
+        done
+        # And restore the immutable bits
+        chattr +i ${rootmnt}/ostree/deploy/*/deploy/*.0 ${rootmnt}
+        echo "...done"
+        umount $rootmnt
+        ;;
+    *)
+        echo "Unsupported operation: ${1:-}"
+        ;;
+esac

dracut/31ignition-ostree/ignition-ostree-rootfs-detect.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Ignition OSTree: detect rootfs replacement
+DefaultDependencies=false
+After=ignition-fetch.service
+Before=ignition-disks.service
+Before=initrd-root-fs.target
+Before=sysroot.mount
+ConditionKernelCommandLine=ostree
+
+# This stage requires udevd to detect disks
+Requires=systemd-udevd.service
+After=systemd-udevd.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+EnvironmentFile=/run/ignition.env
+ExecStart=/usr/libexec/ignition-ostree-dracut-rootfs detect

dracut/31ignition-ostree/ignition-ostree-rootfs-restore.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=Ignition OSTree: restore rootfs
+DefaultDependencies=false
+After=ignition-disks.service
+Before=sysroot.mount
+
+ConditionKernelCommandLine=ostree
+ConditionPathIsDirectory=/run/ignition-ostree-rootfs
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+EnvironmentFile=/run/ignition.env
+# So we can transiently mount sysroot
+MountFlags=slave
+ExecStart=/usr/libexec/ignition-ostree-dracut-rootfs restore

dracut/31ignition-ostree/ignition-ostree-rootfs-save.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Ignition OSTree: save rootfs
+DefaultDependencies=false
+After=ignition-ostree-rootfs-detect.service
+Before=ignition-disks.service
+ConditionKernelCommandLine=ostree
+ConditionPathIsDirectory=/run/ignition-ostree-rootfs
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+EnvironmentFile=/run/ignition.env
+# So we can transiently mount sysroot
+MountFlags=slave
+ExecStart=/usr/libexec/ignition-ostree-dracut-rootfs save

dracut/31ignition-ostree/module-setup.sh

@@ -15,7 +15,9 @@ install_ignition_unit() {
 install() {
     inst_multiple \
         systemd-sysusers \
-        systemd-tmpfiles
+        systemd-tmpfiles \
+        ostree tar chattr \
+        jq
 
     mkdir -p "$initdir/$systemdsystemunitdir/ignition-complete.target.requires"
 
@@ -26,4 +28,9 @@ install() {
     install_ignition_unit ignition-ostree-populate-var.service
     inst_script "$moddir/ignition-ostree-populate-var.sh" \
         "/usr/sbin/ignition-ostree-populate-var"
+    inst_script "$moddir/ignition-ostree-dracut-rootfs.sh" \
+        "/usr/libexec/ignition-ostree-dracut-rootfs"
+    install_ignition_unit ignition-ostree-rootfs-detect.service
+    install_ignition_unit ignition-ostree-rootfs-save.service
+    install_ignition_unit ignition-ostree-rootfs-restore.service
 }