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RFC multifetch protocol
Content from Munin Trac Wiki. Was written by snide between 2010-06-16 and 2010-06-23.
This text follows RFC-like language. Refer to http://rfc.net/rfc2119.html.
- Simple ability for plugins to send sub-5min sampled values
- Storing protocol for [wiki:spec-spooldir spoolfetch repository]
- Simplicity & transparency: storing by append-only
Actually each plugin gives only one value.
- Lightweight plugin
- Ability to have a streaming plugin
- For very high sampling rates (<< 1m) the overhead is noticable.
Proposed new model
A plugin MAY just send many timed-values at once. It MUST then prefix the values with an epoch. This format is mostly used for an efficient spoolfetch storage : the format is plain text and append-only. The different values MAY be separated with a blank line for easier parsing.
The epoch MUST be only increasing.
This enables having a streaming plugin : it never ends when asked for values.
It would be very useful for the cpu plugin that would open a streaming vmstat, massage its output, and restream the output. The advantage would be to have a very little overhead and then avoiding regular monitoring spikes.
field1.value 1234567890:1 field2.value 1234567890:2 field3.value 1234567890:3 field1.value 1234567891:10 field2.value 1234567891:20 field3.value 1234567891:30 field1.value 1234567900:10 field2.value 1234567900:60 field3.value 1234567900:7.3423