create_disk: Make rootfs size small even for qemu/IaaS

For RHCOS with encryption, we encrypt in early boot, and it's beneficial if the root filesystem size is small initially - distinct from the "default disk" size that applies in clouds (and libvirt). This helps RHCOS maintain its default 16G size for libvirt without requiring the installer and other tools to start resizing it. This also increases consistency across metal and virt - we now *always* run `coreos-growfs`.
coreos · Nov 18, 2019 · e441a6a · e441a6a
1 parent 225b113
commit e441a6a
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Showing 2 changed files with 31 additions and 18 deletions.
diff --git a/src/cmd-buildextend-metal b/src/cmd-buildextend-metal
@@ -140,19 +140,26 @@ fi
 img=${name}-${build}-${image_type}.${basearch}.${image_format}
 path=${PWD}/${img}
 
-# For bare metal images, we estimate the disk size. For qemu, we get it from
-# image.yaml.
-if [[ $image_type == metal || $image_type == dasd ]]; then
-    echo "Estimating disk size..."
-    /usr/lib/coreos-assembler/estimate-commit-disk-size --repo "$ostree_repo" "$ref" --add-percent 20 > "$PWD/tmp/ostree-size.json"
-    size="$(jq '."estimate-mb".final' "$PWD/tmp/ostree-size.json")"
-    # extra size is the non-ostree partitions, see create_disk.sh
-    size="$(( size + 513 ))M"
-    echo "Disk size estimated to $size"
-    ignition_platform_id="metal"
-else
-    size="$(python3 -c 'import sys, yaml; print(yaml.safe_load(sys.stdin)["size"])' < "$configdir/image.yaml")G"
-    ignition_platform_id="$image_type"
+ignition_platform_id="${image_type}"
+# dasd is a different disk format, but it's still metal.  Just like
+# if in the future we introduce a 4k sector size x86_64 image type (metal-4k).
+if [ "${image_type}" = dasd ]; then
+    ignition_platform_id=metal
+fi
+
+echo "Estimating disk size..."
+# The additional 35% here is obviously a hack, but we can't easily completely fill the filesystem,
+# and doing so has apparently negative performance implications.
+/usr/lib/coreos-assembler/estimate-commit-disk-size --repo "$ostree_repo" "$ref" --add-percent 35 > "$PWD/tmp/ostree-size.json"
+rootfs_size="$(jq '."estimate-mb".final' "$PWD/tmp/ostree-size.json")"
+# extra size is the non-ostree partitions, see create_disk.sh
+image_size="$(( rootfs_size + 513 ))M"
+echo "Disk size estimated to ${image_size}"
+
+# For bare metal images, we use the estimated image size. For IaaS/virt, we get it from
+# image.yaml because we want a "default" disk size that has some free space.
+if [ "${image_type}" != metal ]; then
+    image_size="$(python3 -c 'import sys, yaml; print(yaml.safe_load(sys.stdin)["size"])' < "$configdir/image.yaml")G"
 fi
 
 kargs="$(python3 -c 'import sys, yaml; args = yaml.safe_load(sys.stdin).get("extra-kargs", []); print(" ".join(args))' < "$configdir/image.yaml")"
@@ -167,7 +174,7 @@ ostree_remote="$(python3 -c 'import sys, yaml; print(yaml.safe_load(sys.stdin).g
 save_var_subdirs="$(python3 -c 'import sys, yaml; print(yaml.safe_load(sys.stdin).get("save-var-subdirs-for-selabel-workaround", "NONE"))' < "$configdir/image.yaml")"
 luks_flag="$(python3 -c 'import sys, yaml; lf=yaml.safe_load(sys.stdin).get("luks_rootfs", ""); print("--luks-rootfs" if lf.lower() in ("yes", "true") else "")' < "$configdir/image.yaml")"
 
-qemu-img create -f ${image_format} "${path}.tmp" "$size"
+qemu-img create -f ${image_format} "${path}.tmp" "${image_size}"
 # We support deploying a commit directly instead of a ref
 ref_arg=${ref}
 if [ -n "${ref_is_temp}" ]; then
@@ -191,6 +198,7 @@ runvm "${target_drive[@]}" -- \
             --ostree-remote "${ostree_remote}" \
             --ostree-repo "${ostree_repo}" \
             --save-var-subdirs "${save_var_subdirs}" \
+            --rootfs-size "${rootfs_size}M" \
             "${luks_flag}"
 mv "${path}.tmp" "$path"
 echo "{}" > tmp/vm-iso-checksum.json

diff --git a/src/create_disk.sh b/src/create_disk.sh
@@ -27,13 +27,15 @@ Options:
     --ostree-remote: the ostree remote
     --ostree-repo: location of the ostree repo
     --save-var-subdirs: "yes" to workaround selabel issue for RHCOS
+    --rootfs-size: Create the root filesystem with specified size
     --luks-rootfs: place rootfs in a LUKS container
 
 You probably don't want to run this script by hand. This script is
 run as part of 'coreos-assembler build'.
 EOC
 }
 
+rootfs_size="0"
 luks_rootfs=""
 extrakargs=""
 
@@ -52,6 +54,7 @@ do
         --ostree-remote)    remote_name="${1}"; shift;;
         --ostree-repo)      ostree="${1}"; shift;;
         --save-var-subdirs) save_var_subdirs="${1}"; shift;;
+        --rootfs-size)      rootfs_size="${1}"; shift;;
         --luks-rootfs)      luks_rootfs=1;;
          *) echo "${flag} is not understood."; usage; exit 10;;
          --) break;
@@ -83,14 +86,16 @@ set -x
 # Pin /boot and / to the partition number 1 and 4 respectivelly
 BOOTPN=1
 ROOTPN=4
+# Make the size relative
+rootfs_size="+${rootfs_size}"
 case "$arch" in
     x86_64)
         sgdisk -Z $disk \
         -U 00000000-0000-4000-a000-000000000001 \
         -n ${BOOTPN}:0:+384M -c ${BOOTPN}:boot \
         -n 2:0:+127M -c 2:EFI-SYSTEM -t 2:C12A7328-F81F-11D2-BA4B-00A0C93EC93B \
         -n 3:0:+1M   -c 3:BIOS-BOOT  -t 3:21686148-6449-6E6F-744E-656564454649 \
-        -n ${ROOTPN}:0:0     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
+        -n ${ROOTPN}:0:${rootfs_size}     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
         sgdisk -p "$disk"
         EFIPN=2
         BIOSPN=3
@@ -100,15 +105,15 @@ case "$arch" in
         -U 00000000-0000-4000-a000-000000000001 \
         -n ${BOOTPN}:0:+384M -c ${BOOTPN}:boot \
         -n 2:0:+127M -c 2:EFI-SYSTEM -t 2:C12A7328-F81F-11D2-BA4B-00A0C93EC93B \
-        -n ${ROOTPN}:0:0     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
+        -n ${ROOTPN}:0:${rootfs_size}     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
         sgdisk -p "$disk"
         EFIPN=2
         ;;
     s390x)
         sgdisk -Z $disk \
         -U 00000000-0000-4000-a000-000000000001 \
         -n ${BOOTPN}:0:+384M -c ${BOOTPN}:boot \
-        -n ${ROOTPN}:0:0     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
+        -n ${ROOTPN}:0:${rootfs_size}     -c ${ROOTPN}:root       -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
         sgdisk -p "$disk"
         ;;
     ppc64le)
@@ -117,7 +122,7 @@ case "$arch" in
         -U 00000000-0000-4000-a000-000000000001 \
         -n 2:0:+4M   -c 2:PowerPC-PReP-boot -t 2:9E1A2D38-C612-4316-AA26-8B49521E5A8B \
         -n ${BOOTPN}:0:+384M -c ${BOOTPN}:boot \
-        -n ${ROOTPN}:0:0     -c ${ROOTPN}:root              -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
+        -n ${ROOTPN}:0:${rootfs_size}     -c ${ROOTPN}:root              -t ${ROOTPN}:0FC63DAF-8483-4772-8E79-3D69D8477DE4
         sgdisk -p "$disk"
         PREPPN=2
         ;;