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clojureriemann

How to clear up Riemann index when a specific event has been received?

I'm writing unit tests for an application which sends events to Riemann. Riemann starts up very slowly, so I decided to launch it once and reuse the instance for all tests. Therefore I need to clean the index from events produced by previous tests in the beginning of each new test.

What I'm trying to do is to configure Riemann in such a way that on receiving a special event it will clear its index. There is an API call that seems to be suitable for the task: http://riemann.io/api/riemann.index.html#var-clear. But I am not very familiar with Clojure and I cannot figure out how to use it. Here is a part of my config:

(streams
  index
  (where (state "clear-all")
    (riemann.index/clear (:index @core))))

But Riemann fails to start with this error: No implementation of method: :clear of protocol: #'riemann.index/Index found for class: nil

This looks like (:index @core) is evaluated to nil.

This does not work too:

(streams
  index
  (where (state "clear-all")
    (riemann.index/clear index)))

The error is: No implementation of method: :clear of protocol: #'riemann.index/Index found for class: riemann.streams$default$stream__9829

Solution

  • Instead trying to evaluate (riemann.index/clear (:index @core)) immediately I need a function which will be called when an event arrives:

    (streams
  (where (state "clear-all")
    (fn [_]
      (riemann.index/clear (:index @core)))
    (else index)))

    Now everything works.