[checkmk-commits] Check_MK Git: check_mk: Implement DNS caching. This can be disabled with use_dns_cache = False

Module: check_mk Branch: master Commit: 86a8123ae52bff6491e18aee3b2d6b7b23e9e7f2 URL: http://git.mathias-kettner.de/git/?p=check_mk.git;a=commit;h=86a8123ae52bff… Author: Mathias Kettner <mk(a)mathias-kettner.de> Date: Wed Sep 18 12:36:08 2013 +0200 Implement DNS caching. This can be disabled with use_dns_cache = False --- ChangeLog | 1 + modules/check_mk.py | 48 +++++++++++++++++++++++----- web/plugins/wato/check_mk_configuration.py | 18 +++++++++++ 3 files changed, 59 insertions(+), 8 deletions(-) diff --git a/ChangeLog b/ChangeLog index 8176726..d8b89fd 100644 --- a/ChangeLog +++ b/ChangeLog @@ -15,6 +15,7 @@ * Preparations for significant SNMP monitoring performance improvement (It's named Inline SNMP, which is available as special feature via subscriptions) * Allow to specify custom host check via WATO (arbitrary command line) + * Implement DNS caching. This can be disabled with use_dns_cache = False Livestatus: * new service column staleness: indicator for outdated service checks diff --git a/modules/check_mk.py b/modules/check_mk.py index 1246046..7267c4e 100755 --- a/modules/check_mk.py +++ b/modules/check_mk.py @@ -211,6 +211,7 @@ agent_port = 6556 agent_ports = [] snmp_ports = [] # UDP ports used for SNMP tcp_connect_timeout = 5.0 +use_dns_cache = True # prevent DNS by using own cache file delay_precompile = False # delay Python compilation to Nagios execution restart_locking = "abort" # also possible: "wait", None check_submission = "file" # alternative: "pipe" @@ -1153,25 +1154,38 @@ def lookup_ipaddress(hostname): if hostname in g_dns_cache: return g_dns_cache[hostname] + # Prepare file based fall-back DNS cache in case resolution fails init_ip_lookup_cache() + cached_ip = g_ip_lookup_cache.get(hostname) + if cached_ip and use_dns_cache: + g_dns_cache[hostname] = cached_ip + return cached_ip + # Now do the actual DNS lookup try: ipa = socket.gethostbyname(hostname) - # Cache the result (persistant) when resolving succeeded - if ipa != g_ip_lookup_cache.get(hostname): + # Update our cached address if that has changed or was missing + if ipa != cached_ip: + if opt_verbose: + print "Updating DNS cache for %s: %s" % (hostname, ipa) g_ip_lookup_cache[hostname] = ipa write_ip_lookup_cache() + + g_dns_cache[hostname] = ipa # Update in-memory-cache + return ipa + except: - # Initialize the lookup cache when called for the first time - if hostname in g_ip_lookup_cache: - ipa = g_ip_lookup_cache[hostname] + # DNS failed. Use cached IP address if present, even if caching + # is disabled. + if cached_ip: + g_dns_cache[hostname] = cached_ip + return cached_ip else: g_dns_cache[hostname] = None raise - g_dns_cache[hostname] = ipa - return ipa + def init_ip_lookup_cache(): global g_ip_lookup_cache @@ -1184,6 +1198,20 @@ def init_ip_lookup_cache(): def write_ip_lookup_cache(): file(var_dir + '/ipaddresses.cache', 'w').write(repr(g_ip_lookup_cache)) +def do_update_dns_cache(): + # Temporarily disable *use* of cache, we want to force an update + global use_dns_cache + use_dns_cache = False + + if opt_verbose: + print "Updating DNS cache..." + for hostname in all_active_hosts() + all_active_clusters(): + # Use intelligent logic. This prevents DNS lookups for hosts + # with statically configured addresses, etc. + lookup_ipaddress(hostname) + + + def agent_port_of(hostname): ports = host_extra_conf(hostname, agent_ports) if len(ports) == 0: @@ -4305,6 +4333,7 @@ def usage(): cmk -D, --dump [H1 H2 ..] dump all or some hosts cmk -d HOSTNAME|IPADDRESS show raw information from agent cmk --check-inventory HOSTNAME check for items not yet checked + cmk --update-dns-cache update IP address lookup cache cmk --list-hosts [G1 G2 ...] print list of hosts cmk --list-tag TAG1 TAG2 ... list hosts having certain tags cmk -L, --list-checks list all available check types @@ -5270,7 +5299,7 @@ if __name__ == "__main__": "no-cache", "update", "restart", "reload", "dump", "fake-dns=", "man", "nowiki", "config-check", "backup=", "restore=", "check-inventory=", "paths", "cleanup-autochecks", "checks=", - "cmc-file=", "browse-man", "list-man" ] + "cmc-file=", "browse-man", "list-man", "update-dns-cache" ] non_config_options = ['-L', '--list-checks', '-P', '--package', '-M', '--notify', '--man', '-V', '--version' ,'-h', '--help', '--automation'] @@ -5390,6 +5419,9 @@ if __name__ == "__main__": elif o == '--donate': do_donation() done = True + elif o == '--update-dns-cache': + do_update_dns_cache() + done = True elif o == '--snmpwalk': do_snmpwalk(args) done = True diff --git a/web/plugins/wato/check_mk_configuration.py b/web/plugins/wato/check_mk_configuration.py index 68d5706..ec25642 100644 --- a/web/plugins/wato/check_mk_configuration.py +++ b/web/plugins/wato/check_mk_configuration.py @@ -950,6 +950,24 @@ register_configvar(group, need_restart = True) register_configvar(group, + "use_dns_cache", + Checkbox( + title = _("Use DNS lookup cache"), + label = _("Prevent DNS lookups by use of a cache file"), + help = _("When this option is enabled (which is the default), then Check_MK tries to " + "prevent IP address lookups during the configuration generation. This can speed " + "up this process greatly when you have a larger number of hosts. The cache is stored " + "in a simple file. Note: when the cache is enabled then changes of the IP address " + "of a host in your name server will not be detected immediately. If you need an " + "immediate update then simply disable the cache once, activate the changes and " + "enabled it again. OMD based installations automatically update the cache once " + "a day."), + default_value = True, + ), + need_restart = True +) + +register_configvar(group, "use_inline_snmp", Checkbox( title = _("Use Inline SNMP (EXPERIMENTAL)"),