220 lines
7.0 KiB
Python
220 lines
7.0 KiB
Python
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"""Compatibility with the nrpe-external-master charm"""
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# Copyright 2012 Canonical Ltd.
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#
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# Authors:
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# Matthew Wedgwood <matthew.wedgwood@canonical.com>
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import subprocess
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import pwd
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import grp
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import os
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import re
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import shlex
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import yaml
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from charmhelpers.core.hookenv import (
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config,
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local_unit,
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log,
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relation_ids,
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relation_set,
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)
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from charmhelpers.core.host import service
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# This module adds compatibility with the nrpe-external-master and plain nrpe
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# subordinate charms. To use it in your charm:
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#
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# 1. Update metadata.yaml
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#
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# provides:
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# (...)
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# nrpe-external-master:
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# interface: nrpe-external-master
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# scope: container
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#
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# and/or
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#
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# provides:
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# (...)
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# local-monitors:
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# interface: local-monitors
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# scope: container
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#
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# 2. Add the following to config.yaml
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#
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# nagios_context:
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# default: "juju"
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# type: string
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# description: |
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# Used by the nrpe subordinate charms.
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# A string that will be prepended to instance name to set the host name
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# in nagios. So for instance the hostname would be something like:
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# juju-myservice-0
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# If you're running multiple environments with the same services in them
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# this allows you to differentiate between them.
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#
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# 3. Add custom checks (Nagios plugins) to files/nrpe-external-master
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#
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# 4. Update your hooks.py with something like this:
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#
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# from charmsupport.nrpe import NRPE
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# (...)
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# def update_nrpe_config():
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# nrpe_compat = NRPE()
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# nrpe_compat.add_check(
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# shortname = "myservice",
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# description = "Check MyService",
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# check_cmd = "check_http -w 2 -c 10 http://localhost"
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# )
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# nrpe_compat.add_check(
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# "myservice_other",
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# "Check for widget failures",
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# check_cmd = "/srv/myapp/scripts/widget_check"
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# )
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# nrpe_compat.write()
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#
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# def config_changed():
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# (...)
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# update_nrpe_config()
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#
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# def nrpe_external_master_relation_changed():
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# update_nrpe_config()
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#
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# def local_monitors_relation_changed():
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# update_nrpe_config()
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#
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# 5. ln -s hooks.py nrpe-external-master-relation-changed
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# ln -s hooks.py local-monitors-relation-changed
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class CheckException(Exception):
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pass
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class Check(object):
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shortname_re = '[A-Za-z0-9-_]+$'
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service_template = ("""
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#---------------------------------------------------
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# This file is Juju managed
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#---------------------------------------------------
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define service {{
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use active-service
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host_name {nagios_hostname}
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service_description {nagios_hostname}[{shortname}] """
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"""{description}
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check_command check_nrpe!{command}
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servicegroups {nagios_servicegroup}
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}}
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""")
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def __init__(self, shortname, description, check_cmd):
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super(Check, self).__init__()
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# XXX: could be better to calculate this from the service name
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if not re.match(self.shortname_re, shortname):
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raise CheckException("shortname must match {}".format(
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Check.shortname_re))
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self.shortname = shortname
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self.command = "check_{}".format(shortname)
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# Note: a set of invalid characters is defined by the
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# Nagios server config
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# The default is: illegal_object_name_chars=`~!$%^&*"|'<>?,()=
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self.description = description
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self.check_cmd = self._locate_cmd(check_cmd)
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def _locate_cmd(self, check_cmd):
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search_path = (
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'/usr/lib/nagios/plugins',
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'/usr/local/lib/nagios/plugins',
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)
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parts = shlex.split(check_cmd)
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for path in search_path:
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if os.path.exists(os.path.join(path, parts[0])):
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command = os.path.join(path, parts[0])
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if len(parts) > 1:
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command += " " + " ".join(parts[1:])
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return command
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log('Check command not found: {}'.format(parts[0]))
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return ''
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def write(self, nagios_context, hostname):
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nrpe_check_file = '/etc/nagios/nrpe.d/{}.cfg'.format(
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self.command)
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with open(nrpe_check_file, 'w') as nrpe_check_config:
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nrpe_check_config.write("# check {}\n".format(self.shortname))
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nrpe_check_config.write("command[{}]={}\n".format(
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self.command, self.check_cmd))
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if not os.path.exists(NRPE.nagios_exportdir):
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log('Not writing service config as {} is not accessible'.format(
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NRPE.nagios_exportdir))
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else:
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self.write_service_config(nagios_context, hostname)
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def write_service_config(self, nagios_context, hostname):
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for f in os.listdir(NRPE.nagios_exportdir):
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if re.search('.*{}.cfg'.format(self.command), f):
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os.remove(os.path.join(NRPE.nagios_exportdir, f))
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templ_vars = {
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'nagios_hostname': hostname,
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'nagios_servicegroup': nagios_context,
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'description': self.description,
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'shortname': self.shortname,
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'command': self.command,
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}
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nrpe_service_text = Check.service_template.format(**templ_vars)
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nrpe_service_file = '{}/service__{}_{}.cfg'.format(
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NRPE.nagios_exportdir, hostname, self.command)
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with open(nrpe_service_file, 'w') as nrpe_service_config:
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nrpe_service_config.write(str(nrpe_service_text))
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def run(self):
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subprocess.call(self.check_cmd)
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class NRPE(object):
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nagios_logdir = '/var/log/nagios'
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nagios_exportdir = '/var/lib/nagios/export'
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nrpe_confdir = '/etc/nagios/nrpe.d'
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def __init__(self, hostname=None):
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super(NRPE, self).__init__()
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self.config = config()
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self.nagios_context = self.config['nagios_context']
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self.unit_name = local_unit().replace('/', '-')
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if hostname:
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self.hostname = hostname
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else:
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self.hostname = "{}-{}".format(self.nagios_context, self.unit_name)
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self.checks = []
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def add_check(self, *args, **kwargs):
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self.checks.append(Check(*args, **kwargs))
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def write(self):
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try:
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nagios_uid = pwd.getpwnam('nagios').pw_uid
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nagios_gid = grp.getgrnam('nagios').gr_gid
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except:
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log("Nagios user not set up, nrpe checks not updated")
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return
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if not os.path.exists(NRPE.nagios_logdir):
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os.mkdir(NRPE.nagios_logdir)
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os.chown(NRPE.nagios_logdir, nagios_uid, nagios_gid)
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nrpe_monitors = {}
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monitors = {"monitors": {"remote": {"nrpe": nrpe_monitors}}}
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for nrpecheck in self.checks:
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nrpecheck.write(self.nagios_context, self.hostname)
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nrpe_monitors[nrpecheck.shortname] = {
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"command": nrpecheck.command,
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}
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service('restart', 'nagios-nrpe-server')
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for rid in relation_ids("local-monitors"):
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relation_set(relation_id=rid, monitors=yaml.dump(monitors))
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