pvc/node-daemon/pvcnoded/util/fencing.py

#!/usr/bin/env python3

# fencing.py - Utility functions for pvcnoded fencing
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2021 Joshua M. Boniface <joshua@boniface.me>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################

import time

import daemon_lib.common as common

from pvcnoded.objects.VMInstance import VMInstance


#
# Fence thread entry function
#
def fence_node(node_name, zkhandler, config, logger):
    # We allow exactly 6 saving throws (30 seconds) for the host to come back online or we kill it
    failcount_limit = 6
    failcount = 0
    while failcount < failcount_limit:
        # Wait 5 seconds
        time.sleep(config["keepalive_interval"])
        # Get the state
        node_daemon_state = zkhandler.read(("node.state.daemon", node_name))
        # Is it still 'dead'
        if node_daemon_state == "dead":
            failcount += 1
            logger.out(
                'Node "{}" failed {}/{} saving throws'.format(
                    node_name, failcount, failcount_limit
                ),
                state="s",
            )
        # It changed back to something else so it must be alive
        else:
            logger.out(
                'Node "{}" passed a saving throw; canceling fence'.format(node_name),
                state="o",
            )
            return

    logger.out('Fencing node "{}" via IPMI reboot signal'.format(node_name), state="s")

    # Get IPMI information
    ipmi_hostname = zkhandler.read(("node.ipmi.hostname", node_name))
    ipmi_username = zkhandler.read(("node.ipmi.username", node_name))
    ipmi_password = zkhandler.read(("node.ipmi.password", node_name))

    # Shoot it in the head
    fence_status = reboot_via_ipmi(ipmi_hostname, ipmi_username, ipmi_password, logger)

    # Hold to ensure the fence takes effect and system stabilizes
    logger.out(
        'Waiting {}s for fence of node "{}" to take effect'.format(
            config["keepalive_interval"], node_name
        ),
        state="i",
    )
    time.sleep(config["keepalive_interval"])

    if fence_status:
        logger.out('Marking node "{}" as fenced'.format(node_name), state="i")
        while True:
            try:
                zkhandler.write([(("node.state.daemon", node_name), "fenced")])
                break
            except Exception:
                continue

    # Force into secondary network state if needed
    if node_name in config["coordinators"]:
        logger.out(
            'Forcing secondary status for node "{}"'.format(node_name), state="i"
        )
        zkhandler.write([(("node.state.router", node_name), "secondary")])
        if zkhandler.read("base.config.primary_node") == node_name:
            zkhandler.write([("base.config.primary_node", "none")])

    # If the fence succeeded and successful_fence is migrate
    if fence_status and config["successful_fence"] == "migrate":
        migrateFromFencedNode(zkhandler, node_name, config, logger)

    # If the fence failed and failed_fence is migrate
    if (
        not fence_status
        and config["failed_fence"] == "migrate"
        and config["suicide_intervals"] != "0"
    ):
        migrateFromFencedNode(zkhandler, node_name, config, logger)


# Migrate hosts away from a fenced node
def migrateFromFencedNode(zkhandler, node_name, config, logger):
    logger.out(
        'Migrating VMs from dead node "{}" to new hosts'.format(node_name), state="i"
    )

    # Get the list of VMs
    dead_node_running_domains = zkhandler.read(
        ("node.running_domains", node_name)
    ).split()

    # Set the node to a custom domainstate so we know what's happening
    zkhandler.write([(("node.state.domain", node_name), "fence-flush")])

    # Migrate a VM after a flush
    def fence_migrate_vm(dom_uuid):
        VMInstance.flush_locks(zkhandler, logger, dom_uuid)

        target_node = common.findTargetNode(zkhandler, dom_uuid)

        if target_node is not None:
            logger.out(
                'Migrating VM "{}" to node "{}"'.format(dom_uuid, target_node),
                state="i",
            )
            zkhandler.write(
                [
                    (("domain.state", dom_uuid), "start"),
                    (("domain.node", dom_uuid), target_node),
                    (("domain.last_node", dom_uuid), node_name),
                ]
            )
        else:
            logger.out(
                'No target node found for VM "{}"; VM will autostart on next unflush/ready of current node'.format(
                    dom_uuid
                ),
                state="i",
            )
            zkhandler.write(
                {
                    (("domain.state", dom_uuid), "stopped"),
                    (("domain.meta.autostart", dom_uuid), "True"),
                }
            )

    # Loop through the VMs
    for dom_uuid in dead_node_running_domains:
        fence_migrate_vm(dom_uuid)

    # Set node in flushed state for easy remigrating when it comes back
    zkhandler.write([(("node.state.domain", node_name), "flushed")])
    logger.out(
        'All VMs flushed from dead node "{}" to new hosts'.format(node_name), state="i"
    )


#
# Perform an IPMI fence
#
def reboot_via_ipmi(ipmi_hostname, ipmi_user, ipmi_password, logger):
    # Power off the node the node
    logger.out("Sending power off to dead node", state="i")
    ipmi_command_stop = (
        "/usr/bin/ipmitool -I lanplus -H {} -U {} -P {} chassis power off".format(
            ipmi_hostname, ipmi_user, ipmi_password
        )
    )
    ipmi_stop_retcode, ipmi_stop_stdout, ipmi_stop_stderr = common.run_os_command(
        ipmi_command_stop
    )

    if ipmi_stop_retcode != 0:
        logger.out(f"Failed to power off dead node: {ipmi_stop_stderr}", state="e")

    time.sleep(5)

    # Check the chassis power state
    logger.out("Checking power state of dead node", state="i")
    ipmi_command_status = (
        "/usr/bin/ipmitool -I lanplus -H {} -U {} -P {} chassis power status".format(
            ipmi_hostname, ipmi_user, ipmi_password
        )
    )
    ipmi_status_retcode, ipmi_status_stdout, ipmi_status_stderr = common.run_os_command(
        ipmi_command_status
    )
    if ipmi_status_retcode == 0:
        logger.out(
            f"Current chassis power state is: {ipmi_status_stdout.strip()}", state="i"
        )
    else:
        logger.out("Current chassis power state is: Unknown", state="w")

    # Power on the node
    logger.out("Sending power on to dead node", state="i")
    ipmi_command_start = (
        "/usr/bin/ipmitool -I lanplus -H {} -U {} -P {} chassis power on".format(
            ipmi_hostname, ipmi_user, ipmi_password
        )
    )
    ipmi_start_retcode, ipmi_start_stdout, ipmi_start_stderr = common.run_os_command(
        ipmi_command_start
    )

    if ipmi_start_retcode != 0:
        logger.out(f"Failed to power on dead node: {ipmi_start_stderr}", state="w")

    time.sleep(2)

    # Check the chassis power state
    logger.out("Checking power state of dead node", state="i")
    ipmi_command_status = (
        "/usr/bin/ipmitool -I lanplus -H {} -U {} -P {} chassis power status".format(
            ipmi_hostname, ipmi_user, ipmi_password
        )
    )
    ipmi_status_retcode, ipmi_status_stdout, ipmi_status_stderr = common.run_os_command(
        ipmi_command_status
    )

    if ipmi_stop_retcode == 0:
        if ipmi_status_stdout.strip() == "Chassis Power is on":
            # We successfully rebooted the node and it is powered on; this is a succeessful fence
            logger.out("Successfully rebooted dead node", state="o")
            return True
        elif ipmi_status_stdout.strip() == "Chassis Power is off":
            # We successfully rebooted the node but it is powered off; this might be expected or not, but the node is confirmed off so we can call it a successful fence
            logger.out(
                "Chassis power is in confirmed off state after successfuly IPMI reboot; proceeding with fence-flush",
                state="o",
            )
            return True
        else:
            # We successfully rebooted the node but it is in some unknown power state; since this might indicate a silent failure, we must call it a failed fence
            logger.out(
                "Chassis power is in an unknown state ({}) after successful IPMI reboot; not performing fence-flush".format(
                    ipmi_status_stdout.strip()
                ),
                state="e",
            )
            return False
    else:
        if ipmi_status_stdout.strip() == "Chassis Power is off":
            # We failed to reboot the node but it is powered off; it has probably suffered a serious hardware failure, but the node is confirmed off so we can call it a successful fence
            logger.out(
                "Chassis power is in confirmed off state after failed IPMI reboot; proceeding with fence-flush",
                state="o",
            )
            return True
        else:
            # We failed to reboot the node but it is in some unknown power state (including "on"); since this might indicate a silent failure, we must call it a failed fence
            logger.out(
                "Chassis power is not in confirmed off state after failed IPMI reboot; not performing fence-flush",
                state="e",
            )
            return False


#
# Verify that IPMI connectivity to this host exists (used during node init)
#
def verify_ipmi(ipmi_hostname, ipmi_user, ipmi_password):
    ipmi_command = f"/usr/bin/ipmitool -I lanplus -H {ipmi_hostname} -U {ipmi_user} -P {ipmi_password} chassis power status"
    retcode, stdout, stderr = common.run_os_command(ipmi_command, timeout=2)
    if retcode == 0 and stdout.strip() == "Chassis Power is on":
        return True
    else:
        return False