Tips

Query/Target persistence

Use --stats and related options of norikra start.

• --stats=PATH
  • JSON document, stores:
  • configurations: listen address/port, threads, logging
  • targets and queries
  • loaded on process bootstrapping (missing: ignored)
  • stored on process shutdown (overwrite current file)
• --suppress-dump-stat
  • specify not to store stats on process shutdown
• --dump-stat-interval=N
  • store stats dump per specified N seconds (ex: 1800)

Stats will be dumped with SIGUSR2 if --stats=PATH specified. Or, in client side, norikra-client admin stats can export stats json data.

Query grouping

To fetch query output, we have 3 options:

• events RPC (norikra-client event fetch)
  • to fetch output events from a query, and remove these events from server
• see RPC (norikra-client event see)
  • to fetch output events from a query, without removing these events
• sweep RPC (norikra-client event sweep)
  • to fetch output events from queries with same query group name, and remove these events from server

We can fetch many output events from many related queries (per service, per customers, ...) from norikra server by sweep. Query group name is used for this purpose.

Loopback query group

Norikra connects query outputs into other target input by specifying query group as LOOPBACK(target_name).

Once you registered a query with loopback query group, norikra does: 1. check target_name format 1. open target_name if it is not opened yet 1. register the query 1. define fields of target_name by outputs of the query

Loopback query group is supported on Norikra v1.0.0 or later.

STDOUT query group

Norikra provides STDOUT() query group to dump query output events on Console directly.

Listeners

Norikra has a feature named as Listener, to accept output records of queries and to execute any processing for these events. In fact, both of LOOPBACK(...) and STDOUT() are implemented as built-in Listener plugins.

All Listener plugins have its name and just 1 String argument. There are used in query group fields, like NAME(argument).

Users of Norikra can write any other Listener plugins for their own purposes. See documents of norikra-listener-mock repository, and try it.

https://github.com/norikra/norikra-lilstener-mock