Riemann Service Down Alerts

gistfile1.clj

;
; Riemann Service Down Alerts
; ===================================================
;
; The index stores the most recent state for any [host, service] pair. Clients
; can search the index for various states with a basic query language. The
; default implementation is a NonBlockingHashMap.
;

(let [my-index (index)

      ; Let's also define a stream that feeds states into this index. We'll
      ; call it index for short.

      index (update-index my-index)]

  ; When services disappear or fail, their states in the index will get stale.
  ; Periodically, Riemann can scan the index and delete states that have exceeded
  ; their TTL. You'll receive events with the deleted statee's original :host,
  ; :service, and :state "expired".
  ;
  ; To expire old states every ten seconds:

  (periodically-expire 10)

  ; You can select expired events with where, or the expired stream:

  (streams
    (where (state "expired") prn)
    (expired prn))

  ; This way, Riemann can issue an alert for a service that failed to check in
  ; regularly. The default TTL is 60 seconds, but you can submit ttls with each
  ; event or assign them using (with) or (default).

  (streams
    (default :ttl 10 index)

    (by [:host :service]
      (changed :state {:init "ok"}
        #(info "email with event expired" %)))));;(:trigger pd)

  ; Any service that fails to check in within every 10 seconds will be removed
  ; and an alert sent.