Add root-hints to hack

hack/root-hints/README.md

@@ -0,0 +1,118 @@
+## root-hints for deployments
+
+When installing/persisting the OS to disk, a method of selecting the 
+proper disk is needed.
+This is needed because on servers with more than one disk, the order of the device nodes under /dev is arbitrary.
+e.g. /dev/sda and /dev/sdb can inter-change on each boot of the server and point to the wrong disk device.
+
+With root-hints.sh we are proving a simple/small script that is going to be used with a set of roothints provided via a 
+yaml file in order to properly select the right device.
+
+This is nothing more than a way of constructing a filter for lsblk by leveraging scols-filter.
+
+This is supposed to be run inside the initrd together with the installer in order to choose the proper disk.
+The actual root-hints.yaml should be provided via ignition.
+
+At the moment it can be used to filter on all colums provided by lsblk, but in the future this should be limited.
+```
+   ALIGNMENT <integer>       alignment offset
+     ID-LINK <string>        the shortest udev /dev/disk/by-id link name
+          ID <string>        udev ID (based on ID-LINK)
+    DISC-ALN <integer>       discard alignment offset
+         DAX <boolean>       dax-capable device
+   DISC-GRAN <string|number> discard granularity, use <number> if --bytes is given
+    DISK-SEQ <integer>       disk sequence number
+    DISC-MAX <string|number> discard max bytes, use <number> if --bytes is given
+   DISC-ZERO <boolean>       discard zeroes data
+     FSAVAIL <string|number> filesystem size available for unprivileged users, use <number> if --bytes is given
+     FSROOTS <string>        mounted filesystem roots
+      FSSIZE <string|number> filesystem size, use <number> if --bytes is given
+      FSTYPE <string>        filesystem type
+      FSUSED <string|number> filesystem size used, use <number> if --bytes is given
+      FSUSE% <string>        filesystem use percentage
+       FSVER <string>        filesystem version
+       GROUP <string>        group name
+        HCTL <string>        Host:Channel:Target:Lun for SCSI
+     HOTPLUG <boolean>       removable or hotplug device (usb, pcmcia, ...)
+       KNAME <string>        internal kernel device name
+       LABEL <string>        filesystem LABEL
+     LOG-SEC <integer>       logical sector size
+     MAJ:MIN <string>        major:minor device number
+         MAJ <string>        major device number
+         MIN <string>        minor device number
+      MIN-IO <integer>       minimum I/O size
+        MODE <string>        device node permissions
+       MODEL <string>        device identifier
+          MQ <string>        device queues
+        NAME <string>        device name
+      OPT-IO <integer>       optimal I/O size
+       OWNER <string>        user name
+   PARTFLAGS <string>        partition flags
+   PARTLABEL <string>        partition LABEL
+       PARTN <integer>       partition number as read from the partition table
+    PARTTYPE <string>        partition type code or UUID
+PARTTYPENAME <string>        partition type name
+    PARTUUID <string>        partition UUID
+        PATH <string>        path to the device node
+     PHY-SEC <integer>       physical sector size
+      PKNAME <string>        internal parent kernel device name
+      PTTYPE <string>        partition table type
+      PTUUID <string>        partition table identifier (usually UUID)
+          RA <integer>       read-ahead of the device
+        RAND <boolean>       adds randomness
+         REV <string>        device revision
+          RM <boolean>       removable device
+          RO <boolean>       read-only device
+        ROTA <boolean>       rotational device
+     RQ-SIZE <integer>       request queue size
+       SCHED <string>        I/O scheduler name
+      SERIAL <string>        disk serial number
+        SIZE <string|number> size of the device, use <number> if --bytes is given
+       START <integer>       partition start offset (in 512-byte sectors)
+       STATE <string>        state of the device
+  SUBSYSTEMS <string>        de-duplicated chain of subsystems
+  MOUNTPOINT <string>        where the device is mounted
+ MOUNTPOINTS <string>        all locations where device is mounted
+        TRAN <string>        device transport type
+        TYPE <string>        device type
+        UUID <string>        filesystem UUID
+      VENDOR <string>        device vendor
+       WSAME <string|number> write same max bytes, use <number> if --bytes is given
+         WWN <string>        unique storage identifier
+       ZONED <string>        zone model
+     ZONE-SZ <string|number> zone size, use <number> if --bytes is given
+  ZONE-WGRAN <string|number> zone write granularity, use <number> if --bytes is given
+    ZONE-APP <string|number> zone append max bytes, use <number> if --bytes is given
+     ZONE-NR <integer>       number of zones
+   ZONE-OMAX <integer>       maximum number of open zones
+   ZONE-AMAX <integer>       maximum number of active zones
+   ```
+
+The following operators can be used, as supported by scols-filter.
+```
+expr == expr | expr EQ expr
+expr != expr | expr NE expr
+expr >= expr | expr GE expr
+expr <= expr | expr LE expr
+expr >  expr | expr GT expr
+expr <  expr | expr LT expr
+expr =~ string
+expr !~ string
+```
+
+root-hints.yaml example:
+```
+size: lt 13T
+size: gt 500G
+```
+this is providing the filters to select the disks with a size greater than 500GB AND less than 13TB.
+
+How to use:
+```shell
+./root-hints.sh hints.yaml
+sda
+```
+
+Nota bene:
+When using this mechanism to filter the disks, some extra logic should be used with the installer/any other way of
+persisting the data that only one device is selected, otherwise the filter is not specific enough.

hack/root-hints/root-hints.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+
+set -eu
+
+function err() {
+	echo "$@" 1>&2
+}
+
+function filter() {
+	col=$(echo "$1" | cut -d: -f1)
+	f=$(echo "$1" | cut -d: -f2- | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' )
+	r="([a-zA-Z0-9-]+) ([a-zA-Z0-9-]+)"
+	if [[ $f =~ $r ]]; then
+		op="${BASH_REMATCH[1]}"
+		val="${BASH_REMATCH[2]}"
+	else
+		op="eq"
+		val="$f"
+	fi
+	if [ "$op" == "re" ]; then
+		op="=~"
+	fi
+	if [[ $val =~ ^[0-9]+[KMGT]+$ ]]; then
+		val=$(echo "$val" | numfmt --from=iec)
+		echo "and ${col^^} $op ${val}"
+	else
+		echo "and ${col^^} $op \"${val}\""
+	fi
+
+}
+
+yamlFile="$1"
+
+# validate yaml
+
+#if ! yq . "$yamlFile" &> /dev/null; then
+#	err "invalid yaml file provided, exiting"
+#	exit 1
+#fi
+
+#if dev=$(yq -e .dev "$yamlFile" 2> /dev/null); then
+#	echo "$dev"
+#	exit 0
+#fi
+
+flsblk="TYPE eq \"disk\""
+while IFS= read -r r; do
+	f=$(filter "$r")
+	flsblk="$flsblk $f"
+done < <(cat "$yamlFile")
+
+#echo "$flsblk"
+lsblk --filter "$flsblk" --noheadings -o kname