smokeping_master_slave - Man Page

The slaves communicate with the master smokeping server via the normal smokeping web interface. On initial startup each slave connects to the master server and asks for its assignments. When the slave has done a round of probing it connects to the master again to deliver the results.

If the assignment for a slave changes, the master will tell the slave after the slave has delivered its results.

The master and the slaves sign their messages by supplying an HMAC-MD5 code (RFC 2104) of the message and a shared secret. Optionally the whole communication can run over ssl.

    [slave 1]     [slave 2]      [slave 3]
        |             |              |
        +-------+     |     +--------+
                |     |     |
                v     v     v
              +---------------+
              |    master     |
              +---------------+

The slave is a normal smokeping instance setup where the configuration comes from the master instead of a local configuration file.  The slave tries to contact the master server after every round of probing, supplying its results.  If the master server can not be reached, the results will be sent to the server together with the next round of results.  Results will be stored in a file in Perl storable form so that they survive a restart of the smokeping instance.

To configure a master/slave setup, add a slaves section to your smokeping configuration file. Each slave has a section in the slaves part of the master configuration file. The section name must match the hostname of the slave. If some configuration parameter must be set to a special value for the slave, use an override section to configure this.

The slave names must be the names the hosts think they have, not their outside hostnames or ip addresses or anything like that. When the slave calls the master to get its config or report its measurements it will tell the master its 'hostname'. This together with the shared secret is used to authenticate and identify who is who.

 *** Slaves ***
 secrets=/etc/smokeping/slavesecrets.conf 

 +slave1
 display_name=erul22
 location=India
 color=ff0000

 ++override
 Probes.FPing.binary = /usr/bin/fping
 ...

Then in the targets section you can define slaves at every level. Again the settings get inherited by lower order targets and can be overwritten anywhere in the tree.

A slave will then get the appropriate configuration assigned by the server.

 *** Targets ***
 slaves = slave1 slave2
 ...
 +dest1
 slaves =
 ...
 +dest2
 slaves = slave1
 ...
 +dest3
 ...

The data from the slaves will be stored in TargetName~SlaveName.rrd. So the example above would create the following files:

 dest1.rrd
 dest2.rrd
 dest2~slave1.rrd
 dest3.rrd
 dest3~slave1.rrd
 dest3~slave2.rrd

The slavesecrets.conf file contains a colon separated list of hostnames and secrets.

 host1:secret1
 host2:secret2

A smokeping slave setup has no configuration file. It just needs to know that it runs in slave-mode and its secret. The secret is stored in a file for optimal protection. By default the persistent data cache will be located in /tmp/smokeping.$USER.cache.

 ./smokeping --master-url=http://smokeping/smokeping.cgi \
             --cache-dir=/var/smokeping/ \
             --shared-secret=/var/smokeping/secret.txt

The secret.txt file contains a single word, the secret of this slave. It is NOT the same as the slavesecrets.conf file the master uses.