COLLECTD-SNMP(5) | collectd | COLLECTD-SNMP(5) |
collectd-snmp - Documentation of collectd's "snmp plugin"
LoadPlugin snmp # ... <Plugin snmp> <Data "powerplus_voltge_input"> Type "voltage" Table false Instance "input_line1" Scale 0.1 Values "SNMPv2-SMI::enterprises.6050.5.4.1.1.2.1" </Data> <Data "hr_users"> Type "users" Table false Instance "" Shift -1 Values "HOST-RESOURCES-MIB::hrSystemNumUsers.0" </Data> <Data "std_traffic"> Type "if_octets" Table true Instance "IF-MIB::ifDescr" Values "IF-MIB::ifInOctets" "IF-MIB::ifOutOctets" </Data> <Host "some.switch.mydomain.org"> Address "192.168.0.2" Version 1 Community "community_string" Collect "std_traffic" Interval 120 Timeout 10 Retries 1 </Host> <Host "some.server.mydomain.org"> Address "192.168.0.42" Version 2 Community "another_string" Collect "std_traffic" "hr_users" </Host> <Host "secure.router.mydomain.org"> Address "192.168.0.7:165" Version 3 SecurityLevel "authPriv" Username "cosmo" AuthProtocol "SHA" AuthPassphrase "setec_astronomy" PrivacyProtocol "AES" PrivacyPassphrase "too_many_secrets" Collect "std_traffic" </Host> <Host "some.ups.mydomain.org"> Address "tcp:192.168.0.3" Version 1 Community "more_communities" Collect "powerplus_voltge_input" Interval 300 Timeout 5 Retries 5 </Host> </Plugin>
The "snmp plugin" queries other hosts using SNMP, the simple network management protocol, and translates the value it receives to collectd's internal format and dispatches them. Depending on the write plugins you have loaded they may be written to disk or submitted to another instance or whatever you configured.
Because querying a host via SNMP may produce a timeout multiple threads are used to query hosts in parallel. Depending on the number of hosts between one and ten threads are used.
Since the aim of the "snmp plugin" is to provide a generic interface to SNMP, its configuration is not trivial and may take some time.
Since the "Net-SNMP" library is used you can use all the environment variables that are interpreted by that package. See snmpcmd(1) for more details.
There are two types of blocks that can be contained in the "<Plugin snmp>" block: Data and Host:
The Data block defines a list of values or a table of values that are to be queried. The following options can be set:
When Table is set to false, the OIDs given to Values (see below) are queried using the "GET" SNMP command (see snmpget(1)) and transmitted to collectd. One value list is dispatched and, eventually, one file will be written.
When Table is set to true, the OIDs given to Values (see below) are queried using the "GETNEXT" SNMP command until the subtree is left. After all the lists (think: all columns of the table) have been read several values sets will be dispatches and, eventually, several files will be written. If you configure a Type (see above) which needs more than one data source (for example "if_octets" which needs "rx" and "tx") you will need to specify more than one (two, in the example case) OIDs with the Values option. This has nothing to do with the Table setting.
For example, if you want to query the number of users on a system, you can use "HOST-RESOURCES-MIB::hrSystemNumUsers.0". This is one value and belongs to one value list, therefore Table must be set to false. Please note that, in this case, you have to include the sequence number (zero in this case) in the OID.
Counter example: If you want to query the interface table provided by the "IF-MIB", e. g. the bytes transmitted. There are potentially many interfaces, so you will want to set Table to true. Because the "if_octets" type needs two values, received and transmitted bytes, you need to specify two OIDs in the Values setting, in this case likely "IF-MIB::ifHCInOctets" and "IF-MIB::ifHCOutOctets". But, this is because of the Type setting, not the Table setting.
Since the semantic of Instance and Values depends on this setting you need to set it before setting them. Doing vice verse will result in undefined behavior.
If Table is set to true, Instance is interpreted as an SNMP-prefix that will return a list of values. Those values are then used as the actual type-instance. An example would be the "IF-MIB::ifDescr" subtree. variables(5) from the SNMP distribution describes the format of OIDs.
If Table is set to true and Instance is omitted, then "SUBID" will be used as the instance.
If Table is set to false the actual string configured for Instance is copied into the value-list. In this case Instance may be empty, i. e. "".
The "UPS-MIB" is an example where you need this setting: It has voltages of the inlets, outlets and the battery of an UPS. However, it doesn't provide a descriptive column for these voltages. In this case having 1, 2, ... as instances is not enough, because the inlet voltages and outlet voltages may both have the subids 1, 2, ... You can use this setting to distinguish between the different voltages.
If Table is set to true, each OID must be the prefix of all the values to query, e. g. "IF-MIB::ifInOctets" for all the counters of incoming traffic. This subtree is walked (using "GETNEXT") until a value from outside the subtree is returned.
If Table is set to false, each OID must be the OID of exactly one value, e. g. "IF-MIB::ifInOctets.3" for the third counter of incoming traffic.
This value is not applied to counter-values.
This value is not applied to counter-values.
The Host block defines which hosts to query, which SNMP community and version to use and which of the defined Data to query.
The argument passed to the Host block is used as the hostname in the data stored by collectd.
collectd(1), collectd.conf(5), snmpget(1), snmpgetnext(1), variables(5), unix(7)
Florian Forster <octo@collectd.org> Michael Pilat <mike@mikepilat.com>
2019-04-06 | 5.8.1.git |