hack: add migration script for PCS group to constraints
Adds a script to migrate existing iSCSI Pacemaker resources from group membership to standalone resources with colocation/ordering constraints. The script: - Discovers all iSCSI resources in the configured group - Adds colocation and ordering constraints first (non-disruptive) - Then removes resources from the group (they keep running) - Detects orphaned targets (targets without matching LUNs) - Supports --dry-run mode for safe preview - Is idempotent (safe to run multiple times) Anchors (e.g., ZFS pool, VIP) remain in the group as colocation targets. Refs #547 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
Michel Peterson
parent
08d5008651
commit
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#!/usr/bin/env bash
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#
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# migrate-pcs-group-to-constraints.sh
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#
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# Migrates iSCSI target/LUN Pacemaker resources from group membership to
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# standalone resources with colocation and ordering constraints.
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#
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# This eliminates cascading stop/restart of all iSCSI resources when any
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# single resource is added or removed, and enables parallel failover.
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#
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# See: https://github.com/democratic-csi/democratic-csi/issues/547
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#
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# Usage:
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# ./migrate-pcs-group-to-constraints.sh [options]
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#
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# Options:
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# --group NAME Pacemaker group name (default: group-nas)
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# --sudo Use sudo for pcs commands
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# --dry-run Show what would be done without making changes
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# --help Show this help message
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#
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# The script is idempotent — safe to run multiple times.
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# Run on the NAS host where Pacemaker is running, or via SSH.
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set -euo pipefail
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GROUP="group-nas"
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SUDO=""
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DRY_RUN=false
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usage() {
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sed -n '2,/^$/s/^# \?//p' "$0"
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exit 0
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}
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while [[ $# -gt 0 ]]; do
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case $1 in
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--group) GROUP="$2"; shift 2 ;;
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--sudo) SUDO="sudo"; shift ;;
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--dry-run) DRY_RUN=true; shift ;;
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--help) usage ;;
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*) echo "Unknown option: $1"; usage ;;
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esac
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done
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pcs_cmd() {
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if $DRY_RUN; then
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echo "[dry-run] $SUDO pcs $*"
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return 0
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fi
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$SUDO pcs "$@"
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}
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log() { echo "==> $*"; }
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warn() { echo "WARNING: $*" >&2; }
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# --- Discover current group members ---
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log "Reading group '$GROUP' membership..."
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GROUP_MEMBERS=$($SUDO pcs resource group list 2>/dev/null \
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| grep "^${GROUP}:" \
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| sed "s/^${GROUP}: //" \
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| tr ' ' '\n')
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if [[ -z "$GROUP_MEMBERS" ]]; then
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echo "Group '$GROUP' not found or empty. Nothing to migrate."
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exit 0
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fi
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# Separate anchor resources (stay in group) from iSCSI resources (migrate out)
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ANCHORS=()
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TARGETS=()
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LUNS=()
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ORPHAN_TARGETS=()
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while IFS= read -r res; do
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case "$res" in
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target-pvc-*) TARGETS+=("$res") ;;
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lun-pvc-*) LUNS+=("$res") ;;
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*) ANCHORS+=("$res") ;;
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esac
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done <<< "$GROUP_MEMBERS"
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echo ""
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echo "Group '$GROUP' contains:"
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echo " Anchors (stay in group): ${ANCHORS[*]:-none}"
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echo " iSCSI targets to migrate: ${#TARGETS[@]}"
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echo " iSCSI LUNs to migrate: ${#LUNS[@]}"
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# Build a set of PVC IDs that have LUNs for orphan detection
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declare -A LUN_PVCS
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for lun in "${LUNS[@]}"; do
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pvc_id="${lun#lun-}"
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LUN_PVCS["$pvc_id"]=1
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done
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for target in "${TARGETS[@]}"; do
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pvc_id="${target#target-}"
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if [[ -z "${LUN_PVCS[$pvc_id]+x}" ]]; then
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ORPHAN_TARGETS+=("$target")
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fi
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done
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if [[ ${#ORPHAN_TARGETS[@]} -gt 0 ]]; then
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echo ""
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warn "Found ${#ORPHAN_TARGETS[@]} orphaned target(s) without matching LUN:"
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for t in "${ORPHAN_TARGETS[@]}"; do
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echo " $t"
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done
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fi
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TOTAL=$((${#TARGETS[@]} + ${#LUNS[@]}))
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if [[ $TOTAL -eq 0 ]]; then
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echo "No iSCSI resources to migrate."
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exit 0
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fi
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echo ""
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if $DRY_RUN; then
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echo "--- DRY RUN MODE (no changes will be made) ---"
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fi
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echo ""
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# --- Phase 1: Add constraints (while resources are still in the group) ---
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# This is non-disruptive: resources satisfy both group and constraint rules.
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log "Phase 1: Adding colocation and ordering constraints..."
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for target in "${TARGETS[@]}"; do
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pvc_id="${target#target-}"
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# Colocate target with the group anchor (same node)
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log " colocation: $target with $GROUP"
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pcs_cmd constraint colocation add "$target" with "$GROUP" INFINITY 2>/dev/null || true
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# Order: group must be running before target starts
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log " ordering: $GROUP then $target"
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pcs_cmd constraint order "$GROUP" then "$target" 2>/dev/null || true
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done
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for lun in "${LUNS[@]}"; do
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pvc_id="${lun#lun-}"
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target="target-${pvc_id}"
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# Colocate LUN with its target
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log " colocation: $lun with $target"
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pcs_cmd constraint colocation add "$lun" with "$target" INFINITY 2>/dev/null || true
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# Order: target must be running before LUN starts
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log " ordering: $target then $lun"
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pcs_cmd constraint order "$target" then "$lun" 2>/dev/null || true
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done
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echo ""
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# --- Phase 2: Remove iSCSI resources from the group ---
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# Resources become standalone but keep running (non-disruptive).
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# Constraints from Phase 1 ensure they stay on the correct node.
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# We remove in reverse group order (last first) to minimize recalculations.
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log "Phase 2: Removing iSCSI resources from group '$GROUP'..."
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# Build reverse-ordered list of resources to remove
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REMOVE_LIST=()
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for res in "${TARGETS[@]}" "${LUNS[@]}"; do
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REMOVE_LIST+=("$res")
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done
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# Remove in reverse order
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for (( i=${#REMOVE_LIST[@]}-1; i>=0; i-- )); do
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res="${REMOVE_LIST[$i]}"
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log " removing: $res"
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pcs_cmd resource group remove "$GROUP" "$res" 2>/dev/null || true
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done
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echo ""
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# --- Phase 3: Report results ---
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log "Phase 3: Verifying..."
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if ! $DRY_RUN; then
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REMAINING=$($SUDO pcs resource group list 2>/dev/null \
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| grep "^${GROUP}:" \
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| sed "s/^${GROUP}: //")
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echo ""
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echo "Group '$GROUP' now contains: $REMAINING"
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echo ""
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CONSTRAINT_COUNT=$($SUDO pcs constraint colocation 2>/dev/null \
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| grep -c "target-pvc-\|lun-pvc-" || true)
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echo "Colocation constraints for iSCSI resources: $CONSTRAINT_COUNT"
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ORDER_COUNT=$($SUDO pcs constraint order 2>/dev/null \
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| grep -c "target-pvc-\|lun-pvc-" || true)
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echo "Ordering constraints for iSCSI resources: $ORDER_COUNT"
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fi
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echo ""
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log "Migration complete."
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if [[ ${#ORPHAN_TARGETS[@]} -gt 0 ]]; then
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echo ""
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warn "Orphaned targets (no matching LUN) were migrated but may need manual cleanup:"
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for t in "${ORPHAN_TARGETS[@]}"; do
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echo " $SUDO pcs resource delete $t"
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done
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fi
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echo ""
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echo "Next steps:"
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echo " 1. Verify all iSCSI sessions are healthy: iscsiadm -m session"
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echo " 2. Check resource status: $SUDO pcs status resources"
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echo " 3. Test failover in a maintenance window"
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