- Support failover between multiple agents

    - Support table queries
    - Major refactoring of internals. 

1 files changed, 35 insertions, 2 deletions

diff --git a/doc/rrdbot.conf.5 b/doc/rrdbot.conf.5
index ad93496..0a31ce4 100644
--- a/doc/rrdbot.conf.5
+++ b/doc/rrdbot.conf.5
@@ -111,16 +111,21 @@ above should be replaced with the RRD field name. Multiple
 options can be specified if the RRD file has multiple fields. The syntax of the 
 SNMP url is as follows:
 .Bd -literal -offset indent
-snmp[version]://community@host[:port]/oid
+snmp[version]://community@host[:port]/oid[?query=value]
 .Ed
 .Pp
 The following are valid SNMP urls:
 .Bd -literal -offset indent
 snmp://public@gateway.example.com/sysUptime.0
 snmp2c://mycommunity@uplink.example.com/ifInOctets.2
+snmp2c://mycommunity@example.com/ifInOctets?idDescr=eth0
 snmp://public@www.example.com:10161/1.3.6.1.2.1.1.3.0
+snmp://pub@two.example.com,one.example.com/sysUptime.0
 .Ed
 .Pp
+See TABLE QUERIES for more info on how to use the query part. See MULTIPLE HOSTS
+support for info on how to use multiple hosts.
+.Pp
 To test that your SNMP urls are correct you can use the 
 .Xr rrdbot-get 1
 utility.
@@ -254,7 +259,35 @@ option in the configuration file.
 .Pp
 Once you have configuration files in place, you can use the 
 .Xr rrdbot-create 8
-tool to create the needed RRD files in the appropriate places. 
+tool to create the needed RRD files in the appropriate places.
+.Sh MULTIPLE AGENTS
+.Xr rrdbotd 8 
+supports failover between multiple agents. If an SNMP query fails on one agent
+or a value is not found when querying an agent, then it will switch to another
+configured agent. 
+.Pp
+When combined with a query (see TABLE QUERIES) you can use this feature to 
+search for a given value in a table on one of multiple agents.
+.Pp
+To use failover, simply use multiple host names with commas (without a space)
+separating them. For example:
+.Bd -literal -offset indent
+snmp://public@two.example.com,one.example.com/sysUptime.0
+.Ed
+.Sh TABLE QUERIES
+.Xr rrdbotd 8 
+can query a value that corresponds to a certain row in an SNMP table. On 
+many SNMP agents the indexes of rows in tables are not fixed, and this 
+allows you to retrieve a certain value no matter what row of the table 
+it is on.
+.Pp
+Add the OID and value you want to search for in the table to the end 
+of the SNMP URL. Only one query value is supported. 
+.Pp
+For example to get the outbound packet count on the 'eth0' interface, you would use:
+.Bd -literal -offset indent
+snmp://public@example.com/ifInUcastPkts?ifDescr=eth0
+.Ed
 .Sh SEE ALSO
 .Xr rrdbotd 8 ,
 .Xr rrdbot-create 8 ,