Add force_single_node script
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#!/usr/bin/env bash
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# force_single_node - Manually promote a single coordinator node from a degraded cluster
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# Part of the Parallel Virtual Cluster (PVC) system
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#
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# Copyright (C) 2018-2020 Joshua M. Boniface <joshua@boniface.me>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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###############################################################################
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set -o errexit
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set -o pipefail
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usage() {
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echo -e "Manually promote a single coordinator node from a degraded cluster"
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echo -e ""
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echo -e "DANGER: This action will cause a permanent split-brain within the cluster"
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echo -e " which will have to be corrected manually upon cluster restoration."
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echo -e ""
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echo -e "This script is primarily designed for small clusters in situations where 2"
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echo -e "of the 3 coordinators have become unreachable or shut down. It will promote"
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echo -e "the remaining lone_node to act as a standalone coordinator, allowing basic"
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echo -e "cluster functionality to continue in a heavily degraded state until the"
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echo -e "situation can be rectified. This should only be done in exceptional cases"
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echo -e "as a disaster recovery mechanism when the remaining nodes will remain down"
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echo -e "for a significant amount of time but some VMs are required to run. In general,"
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echo -e "use of this script is not advisable."
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echo -e ""
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echo -e "Usage:"
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echo -e " $0 <target_cluster> <lone_node>"
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echo -e ""
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echo -e "Important information:"
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echo -e " * The lone_node must be a fully-qualified name that is directly reachable from"
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echo -e " the local system via SSH."
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echo -e " * The local user must have valid SSH access to the lone_node in the cluster."
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echo -e " * The user on the cluster node must have 'sudo' access."
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}
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fail() {
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echo -e "$@"
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exit 1
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}
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# Arguments
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if [[ -z ${1} || -z ${2} ]]; then
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usage
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exit 1
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fi
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target_cluster="${1}"
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lone_node="${2}"
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lone_node_shortname="${lone_node%%.*}"
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# Attempt to connect to the node
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ssh ${lone_node} which pvc &>/dev/null || fail "Could not SSH to the lone_node host"
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echo "Verification complete."
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echo -n "Allowing Ceph single-node operation... "
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temp_monmap="$( ssh ${lone_node} mktemp )"
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ssh ${lone_node} "sudo systemctl stop ceph-mon@${lone_node_shortname}" &>/dev/null
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ssh ${lone_node} "ceph-mon -i ${lone_node_shortname} --extract-monmap ${temp_monmap}" &>/dev/null
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ssh ${lone_node} "sudo cp ${tmp_monmap} /etc/ceph/monmap.orig" &>/dev/null
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mon_list="$( ssh ${lone_node} strings ${temp_monmap} | sort | uniq )"
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for mon in ${mon_list}; do
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if [[ ${mon} == ${lone_node_shortname} ]]; then
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continue
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fi
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ssh ${lone_node} "sudo monmaptool ${temp_monmap} --rm ${mon}" &>/dev/null
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done
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ssh ${lone_node} "sudo ceph-mon -i ${lone_node_shortname} --inject-monmap ${temp_monmap}" &>/dev/null
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ssh ${lone_node} "sudo systemctl start ceph-mon@${lone_node_shortname}" &>/dev/null
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sleep 5
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ssh ${lone_node} "sudo ceph osd set noout" &>/dev/null
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echo "done."
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echo -e "Restoration steps:"
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echo -e " sudo systemctl stop ceph-mon@${lone_node_shortname}"
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echo -e " sudo ceph-mon -i ${lone_node_shortname} --inject-monmap /etc/ceph/monmap.orig"
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echo -e " sudo systemctl start ceph-mon@${lone_node_shortname}"
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echo -e " sudo ceph osd unset noout"
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echo -n "Allowing Zookeeper single-node operation... "
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temp_zoocfg="$( ssh ${lone_node} mktemp )"
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ssh ${lone_node} "sudo systemctl stop zookeeper"
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ssh ${lone_node} "sudo awk -v lone_node=${lone_node_shortname} '{
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FS="=|:"
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if ( $1 ~ /^server/ ){
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if ($2 == lone_node) {
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print $0
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} else {
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print "#" $0
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}
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} else {
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print $0
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}
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}' /etc/zookeeper/conf/zoo.cfg > ${temp_zoocfg}"
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ssh ${lone_node} "sudo mv /etc/zookeeper/conf/zoo.cfg /etc/zookeeper/conf/zoo.cfg.orig"
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ssh ${lone_node} "sudo mv ${temp_zoocfg} /etc/zookeeper/conf/zoo.cfg"
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ssh ${lone_node} "sudo systemctl start zookeeper"
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echo "done."
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echo -e "Restoration steps:"
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echo -e " sudo systemctl stop zookeeper"
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echo -e " sudo mv /etc/zookeeper/conf/zoo.cfg.orig /etc/zookeeper/conf/zoo.cfg"
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echo -e " sudo systemctl start zookeeper"
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ssh ${lone_node} "sudo systemctl stop ceph-mon@${lone_node_shortname}"
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echo ""
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ssh ${lone_node} "sudo pvc status 2>/dev/null"
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