[collectd] network push/pull model clarification

[Luke Heberling]

On 08/16/2011 10:09 AM, Chris Burroughs wrote:
> My reading of the network [1] and protocol docs [2] is that the model is
> as follows:
>  - local processes push to collectd on localhost via UDP

You can set up more than one instance of collectd on a single host in
order to do this. Typically though, all plugins are loaded into a single
instance of collectd, and the data is exchanged within the process and
sent directly to output plugins (i.e. rrdtool) without the use of any
IP. Local processes external to collectd would typically use the
unixsock plugin to submit data, which of course uses a unix domain
socket, not udp.

>  - collectd on each node pushes via UDP to whichever server(s) are
> running collectd with a plugin for storing data.

collectd can "push" via multicast or unicast udp depending on the
configuration.

>
> Is that an accurate summary?  (And specifically, am I correct that
> collectd avoids any polling over tcp?)

Individual plugins can poll over tcp. For instance, the curl plugin
might grab a web page every collection interval. Aside from this sort of
thing, you are correct in that collectd will not use polling or tcp.

--
Luke Heberling