ocf-managed-container/refactored/managed-container.d/applications/postgresql/demote.sh

# Sourced by managed-container; uses the shared OCF and parameter environment.

node_to_addr()
{
    local target="${1:-}"

    [ -n "${target}" ] || return 1

    corosync-cmapctl 2>/dev/null |
    awk -v target="${target}" '
        /nodelist\.node\.[0-9]+\.name / {
            key=$1
            sub(/\.name$/, "", key)
            names[key]=$NF
        }

        /nodelist\.node\.[0-9]+\.ring0_addr / {
            key=$1
            sub(/\.ring0_addr$/, "", key)
            addrs[key]=$NF
        }

        END {
            for (key in names) {
                if (names[key] == target && addrs[key] != "") {
                    print addrs[key]
                    exit 0
                }
            }
            exit 1
        }
    '
}

managed_demote()
{
    local monitor_rc
    local target_node target_addr
    local local_node slot_name target_port
    local role receiver_status i

    managed_monitor
    monitor_rc=$?

    case "${monitor_rc}" in
        "${OCF_RUNNING_PROMOTED}")
            ;;
        "${OCF_SUCCESS}")
            ocf_log info \
                "PostgreSQL is already unpromoted"
            return "${OCF_SUCCESS}"
            ;;
        "${OCF_NOT_RUNNING}")
            ocf_exit_reason \
                "Cannot complete demotion because PostgreSQL is stopped"
            return "${OCF_ERR_GENERIC}"
            ;;
        *)
            ocf_exit_reason \
                "Cannot demote unhealthy PostgreSQL instance (monitor rc=${monitor_rc})"
            return "${monitor_rc}"
            ;;
    esac

    target_node="$(demote_target)" || {
        ocf_exit_reason \
            "No fresh valid Pacemaker pre-demote target is available"
        return "${OCF_ERR_GENERIC}"
    }

    target_addr="$(node_to_addr "${target_node}")" || {
        ocf_exit_reason \
            "Unable to resolve Pacemaker promotion target ${target_node} through Corosync"
        return "${OCF_ERR_GENERIC}"
    }

    target_port="${REJOIN_SOURCE_PORT:-5432}"
    local_node="$(hostname)"
    slot_name="ha_$(printf '%s' "${local_node}" |
        tr '[:upper:]-' '[:lower:]_')"

    ocf_log info \
        "Preparing controlled demotion of ${local_node}; successor=${target_node} (${target_addr})"

    if ! candidate_is_standby "${target_addr}"; then
        ocf_exit_reason \
            "Promotion target ${target_node} is not a reachable PostgreSQL standby"
        return "${OCF_ERR_GENERIC}"
    fi

    if ! candidate_caught_up "${target_node}"; then
        ocf_exit_reason \
            "Promotion target ${target_node} is not streaming and fully replayed to the current flushed WAL position"
        return "${OCF_ERR_GENERIC}"
    fi

    if ! ensure_remote_slot "${target_addr}" "${slot_name}"; then
        ocf_exit_reason \
            "Unable to ensure physical replication slot ${slot_name} on ${target_node}"
        return "${OCF_ERR_GENERIC}"
    fi

    ocf_log info \
        "Demotion safety checks passed; stopping PostgreSQL primary"

    if ! pg_command '
        BINDIR="$(pg_config --bindir)" || exit 1
        exec "$BINDIR/pg_ctl" \
            -D "$PGDATA" \
            stop -m fast -w
    '
    then
        ocf_exit_reason \
            "pg_ctl stop failed during controlled demotion"
        return "${OCF_ERR_GENERIC}"
    fi

    if pg_running; then
        ocf_exit_reason \
            "PostgreSQL remained running after pg_ctl stop"
        return "${OCF_ERR_GENERIC}"
    fi

    if ! service_running || ! container_running; then
        ocf_exit_reason \
            "Maintenance service/container stopped unexpectedly during demotion"
        return "${OCF_ERR_GENERIC}"
    fi

    ocf_log info \
        "Configuring ${local_node} as cascading standby of ${target_node}"

    if ! mc_runtime_exec \
        --user "${PG_OS_USER}" \
        --env "RA_PRIMARY_HOST=${target_addr}" \
        --env "RA_PRIMARY_PORT=${target_port}" \
        --env "RA_REPLICATION_USER=${REPLICATION_USER}" \
        --env "RA_REPLICATION_SLOT=${slot_name}" \
        --env "RA_APPLICATION_NAME=${local_node}" \
        "${CONTAINER_NAME}" \
        sh -c '
            set -e

            sed -i \
                -e "/^[[:space:]]*primary_conninfo[[:space:]]*=/d" \
                -e "/^[[:space:]]*primary_slot_name[[:space:]]*=/d" \
                "$PGDATA/postgresql.auto.conf"

            printf "%s
" \
                "primary_conninfo = '\''host=${RA_PRIMARY_HOST} port=${RA_PRIMARY_PORT} user=${RA_REPLICATION_USER} application_name=${RA_APPLICATION_NAME}'\''" \
                "primary_slot_name = '\''${RA_REPLICATION_SLOT}'\''" \
                >> "$PGDATA/postgresql.auto.conf"

            touch "$PGDATA/standby.signal"

            chmod 600 \
                "$PGDATA/postgresql.auto.conf" \
                "$PGDATA/standby.signal"
        '
    then
        ocf_exit_reason \
            "Failed to configure PostgreSQL as standby of ${target_node}"
        return "${OCF_ERR_GENERIC}"
    fi

    ocf_log info \
        "Starting PostgreSQL as cascading standby of ${target_node}"

    if ! pg_command '
        BINDIR="$(pg_config --bindir)" || exit 1
        exec "$BINDIR/pg_ctl" \
            -D "$PGDATA" \
            -l "$PGDATA/postgresql.log" \
            start -w
    '
    then
        ocf_exit_reason \
            "PostgreSQL failed to start as cascading standby"
        return "${OCF_ERR_GENERIC}"
    fi

    for i in $(seq 1 30); do
        role="$(pg_role 2>/dev/null || true)"
        receiver_status="$(pg_wal_receiver_status 2>/dev/null || true)"

        if [ "${role}" = "t" ] &&
           [ "${receiver_status}" = "streaming" ]
        then
            ocf_log info \
                "Controlled demotion complete: ${local_node} is streaming from ${target_node}"
            return "${OCF_SUCCESS}"
        fi

        sleep 1
    done

    ocf_exit_reason \
        "PostgreSQL started after demotion but did not become a streaming standby"
    return "${OCF_ERR_GENERIC}"
}