expand_lvm.sh

#!/usr/bin/env bash
# =============================================================================
# expand_lvm.sh - Automatically expand LVM volumes on Ubuntu 24.04
# =============================================================================
# This script:
#   1. Detects unallocated disk space on physical volumes
#   2. Expands the partition table entry if needed
#   3. Resizes PVs, extends VGs, extends LVs, and resizes filesystems
#
# Usage: sudo bash expand_lvm.sh [OPTIONS]
#   -d, --dry-run     Show what would be done without making changes
#   -y, --yes         Skip confirmation prompts
#   -v, --verbose     Enable verbose output
#   -h, --help        Show this help message
#
# Supports: ext2/3/4, xfs filesystems
# Requires: lvm2, parted, growpart (cloud-guest-utils), e2fsprogs/xfsprogs
# =============================================================================

set -euo pipefail

# ── Colours ──────────────────────────────────────────────────────────────────
RED='\033[0;31m'; YELLOW='\033[1;33m'; GREEN='\033[0;32m'
CYAN='\033[0;36m'; BOLD='\033[1m'; RESET='\033[0m'

# ── Defaults ─────────────────────────────────────────────────────────────────
DRY_RUN=false
AUTO_YES=false
VERBOSE=false
ERRORS=0
CHANGES_MADE=false

# ── Helpers ──────────────────────────────────────────────────────────────────
log()     { echo -e "${CYAN}[INFO]${RESET}  $*"; }
ok()      { echo -e "${GREEN}[OK]${RESET}    $*"; }
warn()    { echo -e "${YELLOW}[WARN]${RESET}  $*"; }
error()   { echo -e "${RED}[ERROR]${RESET} $*" >&2; (( ERRORS++ )) || true; }
verbose() { $VERBOSE && echo -e "        $*" || true; }
header()  { echo -e "\n${BOLD}${CYAN}=== $* ===${RESET}"; }
dry()     { echo -e "${YELLOW}[DRY]${RESET}   (would run) $*"; }

run() {
    if $DRY_RUN; then
        dry "$*"
    else
        verbose "Running: $*"
        eval "$*"
    fi
}

usage() {
    sed -n '/^# Usage:/,/^# ====/p' "$0" | grep -E '^#' | sed 's/^# \?//'
    exit 0
}

confirm() {
    $AUTO_YES && return 0
    read -rp "$(echo -e "${YELLOW}Proceed? [y/N]${RESET} ")" ans
    [[ "${ans,,}" == "y" ]] || { warn "Skipped."; return 1; }
}

bytes_to_human() {
    local b=$1
    if   (( b >= 1073741824 )); then printf "%.1f GiB" "$(echo "scale=1; $b/1073741824" | bc)"
    elif (( b >= 1048576    )); then printf "%.1f MiB" "$(echo "scale=1; $b/1048576"    | bc)"
    else printf "%d KiB" $(( b / 1024 ))
    fi
}

# ── Argument parsing ──────────────────────────────────────────────────────────
while [[ $# -gt 0 ]]; do
    case $1 in
        -d|--dry-run) DRY_RUN=true ;;
        -y|--yes)     AUTO_YES=true ;;
        -v|--verbose) VERBOSE=true ;;
        -h|--help)    usage ;;
        *) error "Unknown option: $1"; usage ;;
    esac
    shift
done

# ── Root check ────────────────────────────────────────────────────────────────
if [[ $EUID -ne 0 ]]; then
    error "This script must be run as root (use sudo)."
    exit 1
fi

# ── Dependency check ──────────────────────────────────────────────────────────
header "Checking dependencies"
MISSING=()
for cmd in pvs vgs lvs pvresize pvscan vgextend lvextend \
           parted growpart resize2fs xfs_growfs lsblk bc; do
    if ! command -v "$cmd" &>/dev/null; then
        MISSING+=("$cmd")
    fi
done

if [[ ${#MISSING[@]} -gt 0 ]]; then
    warn "Missing tools: ${MISSING[*]}"
    log "Installing missing packages..."
    run "apt-get update -qq"
    run "apt-get install -y cloud-guest-utils lvm2 parted e2fsprogs xfsprogs bc"
fi
ok "All dependencies satisfied."

# ── Discover LVM layout ───────────────────────────────────────────────────────
header "Current LVM layout"

echo ""
echo "Physical Volumes:"
pvs --units b --nosuffix -o pv_name,pv_size,pv_free --separator '  ' 2>/dev/null || true

echo ""
echo "Volume Groups:"
vgs --units b --nosuffix -o vg_name,vg_size,vg_free --separator '  ' 2>/dev/null || true

echo ""
echo "Logical Volumes:"
lvs -o lv_name,vg_name,lv_size,lv_path --separator '  ' 2>/dev/null || true

# ── Step 1: Grow partitions that back PVs ────────────────────────────────────
header "Step 1: Expand partitions backing Physical Volumes"

mapfile -t PV_PATHS < <(pvs --noheadings -o pv_name 2>/dev/null | tr -d ' ')

for PV in "${PV_PATHS[@]}"; do
    [[ -z "$PV" ]] && continue
    log "Examining PV: $PV"

    # Resolve underlying disk and partition number
    # Handles /dev/sda2, /dev/nvme0n1p3, /dev/vda1, /dev/xvda1 etc.
    if [[ "$PV" =~ ^(/dev/[a-z]+)([0-9]+)$ ]]; then
        DISK="${BASH_REMATCH[1]}"
        PART="${BASH_REMATCH[2]}"
    elif [[ "$PV" =~ ^(/dev/[a-z]+[0-9]+p)([0-9]+)$ ]]; then
        DISK="${BASH_REMATCH[1]%p}"
        PART="${BASH_REMATCH[2]}"
    else
        warn "  Cannot parse disk/partition from $PV — skipping growpart."
        continue
    fi

    verbose "  Disk: $DISK  Partition: $PART"

    # Check if growpart would do anything
    GROW_OUT=$(growpart "$DISK" "$PART" 2>&1) && GREW=true || GREW=false

    if $GREW; then
        ok "  Grew partition ${DISK}${PART}: $GROW_OUT"
        CHANGES_MADE=true
    else
        if echo "$GROW_OUT" | grep -qi "NOCHANGE"; then
            verbose "  Partition already at maximum size — nothing to grow."
        else
            if $DRY_RUN; then
                dry "growpart $DISK $PART"
            else
                warn "  growpart output: $GROW_OUT"
            fi
        fi
    fi
done

# ── Step 2: pvresize ──────────────────────────────────────────────────────────
header "Step 2: Resize Physical Volumes (pvresize)"

for PV in "${PV_PATHS[@]}"; do
    [[ -z "$PV" ]] && continue
    PV_FREE_BEFORE=$(pvs --noheadings --units b --nosuffix -o pv_free "$PV" 2>/dev/null | tr -d ' ')
    log "pvresize $PV"
    run "pvresize '$PV'"
    if ! $DRY_RUN; then
        PV_FREE_AFTER=$(pvs --noheadings --units b --nosuffix -o pv_free "$PV" 2>/dev/null | tr -d ' ')
        GAINED=$(( PV_FREE_AFTER - PV_FREE_BEFORE ))
        if (( GAINED > 0 )); then
            ok "  Gained $(bytes_to_human $GAINED) of free PE space on $PV"
            CHANGES_MADE=true
        else
            verbose "  No new space found on $PV"
        fi
    fi
done

# ── Step 3: Extend LVs to consume free VG space ───────────────────────────────
header "Step 3: Extend Logical Volumes"

mapfile -t VG_NAMES < <(vgs --noheadings -o vg_name 2>/dev/null | tr -d ' ')

for VG in "${VG_NAMES[@]}"; do
    [[ -z "$VG" ]] && continue

    VG_FREE=$(vgs --noheadings --units b --nosuffix -o vg_free "$VG" 2>/dev/null | tr -d ' ')
    verbose "VG $VG free space: $(bytes_to_human $VG_FREE)"

    if (( VG_FREE < 4194304 )); then   # < 4 MiB — nothing worth extending
        log "VG $VG: no significant free space ($(bytes_to_human $VG_FREE)) — skipping."
        continue
    fi

    log "VG $VG has $(bytes_to_human $VG_FREE) free — looking for LVs to extend."

    # Find all LVs in this VG
    mapfile -t LV_PATHS < <(lvs --noheadings -o lv_path --select "vg_name=$VG" 2>/dev/null | tr -d ' ')

    if [[ ${#LV_PATHS[@]} -eq 0 ]]; then
        warn "  No LVs found in VG $VG."
        continue
    fi

    # If there's only one LV, give it everything automatically
    if [[ ${#LV_PATHS[@]} -eq 1 ]]; then
        LV="${LV_PATHS[0]}"
        log "  Single LV detected: $LV — extending to use all free space."
        if ! $AUTO_YES; then
            echo -e "  Will run: ${BOLD}lvextend -l +100%FREE '$LV'${RESET}"
            confirm || continue
        fi
        run "lvextend -l +100%FREE '$LV'"
        CHANGES_MADE=true
    else
        # Multiple LVs — show the user and ask which to extend
        echo ""
        echo "  Multiple LVs in VG $VG:"
        i=1
        for L in "${LV_PATHS[@]}"; do
            SZ=$(lvs --noheadings --units h -o lv_size "$L" 2>/dev/null | tr -d ' ')
            echo "    $i) $L  ($SZ)"
            (( i++ ))
        done
        echo ""
        if $AUTO_YES; then
            # In auto mode extend the first/root LV
            LV="${LV_PATHS[0]}"
            warn "  --yes specified: auto-extending first LV: $LV"
        else
            read -rp "  Enter LV number to extend (or 'a' for all, 's' to skip): " CHOICE
            case "$CHOICE" in
                a)
                    for LV in "${LV_PATHS[@]}"; do
                        SHARE=$(( VG_FREE / ${#LV_PATHS[@]} ))
                        run "lvextend -L +${SHARE}B '$LV' 2>/dev/null || lvextend -l +100%FREE '$LV'"
                        CHANGES_MADE=true
                    done
                    LV=""
                    ;;
                s) warn "  Skipped VG $VG."; LV=""; continue ;;
                [0-9]*)
                    IDX=$(( CHOICE - 1 ))
                    LV="${LV_PATHS[$IDX]:-}"
                    [[ -z "$LV" ]] && { warn "Invalid selection."; continue; }
                    ;;
                *) warn "  Invalid input — skipping."; LV=""; continue ;;
            esac
        fi
        if [[ -n "${LV:-}" ]]; then
            run "lvextend -l +100%FREE '$LV'"
            CHANGES_MADE=true
        fi
    fi
done

# ── Step 4: Resize filesystems ────────────────────────────────────────────────
header "Step 4: Resize filesystems"

mapfile -t ALL_LVS < <(lvs --noheadings -o lv_path 2>/dev/null | tr -d ' ')

for LV in "${ALL_LVS[@]}"; do
    [[ -z "$LV" ]] && continue

    # Detect filesystem type
    FSTYPE=$(blkid -o value -s TYPE "$LV" 2>/dev/null || echo "unknown")
    verbose "  $LV → fstype=$FSTYPE"

    case "$FSTYPE" in
        ext2|ext3|ext4)
            log "  Resizing ext filesystem on $LV …"
            if $DRY_RUN; then
                dry "resize2fs '$LV'"
            else
                resize2fs "$LV" && ok "  resize2fs succeeded on $LV" || warn "  resize2fs failed on $LV (may already be optimal)"
            fi
            ;;
        xfs)
            # xfs_growfs requires the mount point, not the device
            MOUNT=$(findmnt -n -o TARGET "$LV" 2>/dev/null || true)
            if [[ -n "$MOUNT" ]]; then
                log "  Resizing XFS on $LV (mount: $MOUNT) …"
                run "xfs_growfs '$MOUNT'"
                ok "  xfs_growfs succeeded on $MOUNT"
            else
                warn "  XFS on $LV is not mounted — cannot resize online. Mount it first."
            fi
            ;;
        swap)
            verbose "  $LV is swap — skipping filesystem resize."
            ;;
        unknown|"")
            verbose "  $LV: no recognised filesystem — skipping resize."
            ;;
        *)
            warn "  $LV: unsupported filesystem '$FSTYPE' — resize manually."
            ;;
    esac
done

# ── Summary ───────────────────────────────────────────────────────────────────
header "Final LVM layout"

echo ""
echo "Physical Volumes:"
pvs --units h -o pv_name,pv_size,pv_free 2>/dev/null || true
echo ""
echo "Volume Groups:"
vgs --units h -o vg_name,vg_size,vg_free 2>/dev/null || true
echo ""
echo "Logical Volumes + filesystem usage:"
lvs -o lv_path,lv_size 2>/dev/null | while read -r LV _; do
    [[ "$LV" == "Path" ]] && continue
    MOUNT=$(findmnt -n -o TARGET "$LV" 2>/dev/null || echo "(not mounted)")
    if [[ "$MOUNT" != "(not mounted)" ]]; then
        DF=$(df -h "$MOUNT" 2>/dev/null | awk 'NR==2 {print $2, "used:", $3, "avail:", $4}')
        echo "  $LV  [$MOUNT]  $DF"
    else
        echo "  $LV  $MOUNT"
    fi
done

echo ""
if $DRY_RUN; then
    warn "Dry-run mode — no changes were made."
elif $CHANGES_MADE; then
    ok "LVM expansion complete."
else
    ok "Nothing to do — all volumes are already at maximum size."
fi

if (( ERRORS > 0 )); then
    error "$ERRORS error(s) encountered. Review output above."
    exit 1
fi

exit 0