Configuring SNMP Support¶
Keepalived provides an SNMP subsystem that can gather various metrics about the
VRRP stack and the health checker system. The keepalived MIB is in
doc directory of the project. The base SNMP OID for the MIB is
.18.104.22.168.4.1.9586.100.5, which is hosted under the Debian OID space
assigned by IANA.
Install the SNMP protocol tools and libraries onto your system. This requires the installation of a few packages:
yum install net-snmp net-snmp-utils net-snmp-libs
Once SNMP has been installed on your system, configure keepalived with SNMP
support. When compiling keepalived, add the
option. For example:
During the configure step of the compiling process, you will get a
configuration summary before building with
make. For example, you may see
similar output on a CentOS 6 machine:
./configure --prefix=/usr/local/keepalived-1.2.15 --enable-snmp Keepalived configuration ------------------------ Keepalived version : 1.2.15 Compiler : gcc Compiler flags : -g -O2 -I/usr/include/libnl3 Extra Lib : -Wl,-z,relro -Wl,-z,now -L/usr/lib64 -lnetsnmpagent -lnetsnmphelpers -lnetsnmpmibs -lnetsnmp -Wl,-E -Wl,-rpath,/usr/lib64/perl5/CORE -lssl -lcrypto -lcrypt -lnl-genl-3 -lnl-3 Use IPVS Framework : Yes IPVS sync daemon support : Yes IPVS use libnl : Yes fwmark socket support : Yes Use VRRP Framework : Yes Use VRRP VMAC : Yes SNMP support : Yes SHA1 support : No Use Debug flags : No
Notice the Extra Lib section of the configuration summary. It lists various library flags that gcc will use to build keepalived, several of which have to do with SNMP.
Enable SNMP AgentX support by including the following line in the SNMP
daemon configuration file, typically
/etc/snmp/snmpd.conf if you installed
via RPMs on a CentOS machine:
Be sure to reload or restart the SNMP service for the configuration change to take effect.
Adding the MIB¶
You can query keepalived SNMP managed objects by using the OID. For example:
snmpwalk -v2c -c public localhost .22.214.171.124.4.1.95126.96.36.199.1.0 SNMPv2-SMI::enterprises.95188.8.131.52.1.0 = STRING: "Keepalived v1.2.15 (01/10,2015)"
Alternatively, with the keepalived MIB, you can query using the MIB available from the project. First, copy the MIB to the system’s global MIB directory or to the user’s local MIB directory:
cp /usr/local/src/keepalived-1.2.15/doc/KEEPALIVED-MIB /usr/share/snmp/mibs
cp /usr/local/src/keepalived-1.2.15/doc/KEEPALIVED-MIB ~/.snmp/mibs
The SNMP daemon will check both directories for the existence of the MIB. Once the MIB is in place, the SNMP query can look as follows:
snmpwalk -v2c -c public localhost KEEPALIVED-MIB::version KEEPALIVED-MIB::version.0 = STRING: Keepalived v1.2.15 (01/10,2015)
There are four main sections to the keepalived MIB:
The global section includes objects that contain information about the keepalived instance such as version, router ID and administrative email addresses.
The VRRP section includes objects that contain information about each configured VRRP instance. Within each instance, there are objects that include instance name, current state, and virtual IP addresses.
The Check section includes objects that contain information about each configured virtual server. It includes server tables for virtual and real servers and also configured load balancing algorithms, load balancing method, protocol, status, real and virtual server network connection statistics.
Use a MIB browser, such as mbrowse, to see what managed objects are available to query for monitoring the health of your LVS servers.