salutem.core.checks — io.logicblocks/salutem.core 0.1.2

Provides constructors, predicates and evaluation functions for checks.

attempt clj

(attempt dependencies trigger-id check context)

(attempt dependencies trigger-id check context result-channel)

background-check clj

(background-check check-name check-fn)

(background-check check-name check-fn opts)

Constructs a background check with the provided name and check function.

A background check is one that is evaluated periodically with the result cached in a registry until the next evaluation, conducted by a maintenance pipeline, which will occur once the time to re-evaluation of the check has passed.

Background checks are useful for external dependencies where it is important not to perform the check too frequently and where the health status only needs to be accurate on the order of the time to re-evaluation.

Takes the following parameters:

• check-name: a keyword representing the name of the check
• check-fn: an arity-2 function, with the first argument being a context map as provided during evaluation or at maintenance pipeline construction and the second argument being a callback function which should be called with the result of the check to signal the check is complete; note, check functions must be non-blocking.
• opts: an optional map of additional options for the check, containing:
  • :timeout: a [[salutem.time/duration]] representing the amount of time to wait for the check to complete before considering it failed, defaulting to 10 seconds
  • :time-to-re-evaluation: a [[salutem.time/duration]] representing the time to wait after a check is evaluated before attempting to re-evaluate it, defaulting to 10 seconds.

Note that a result for a background check may live for longer than the time to re-evaluation since evaluation takes time and the result will continue to be returned from the registry whenever the check us resolved until the evaluation has completed and the new result has been added to the registry.

background? clj

(background? check)

Returns true if the provided check is a background check, false otherwise.

evaluate clj

(evaluate check)

(evaluate check context)

(evaluate check context callback-fn)

Evaluates the provided check, returning the result of the evaluation.

Optionally takes a context map containing arbitrary context required by the check in order to run and passed to the check function as the first argument.

By default, the check is evaluated synchronously. If a callback function is provided, the function starts evaluation asynchronously, returns immediately and invokes the callback function with the result once available.

realtime-check clj

(realtime-check check-name check-fn)

(realtime-check check-name check-fn opts)

Constructs a realtime check with the provided name and check function.

A realtime check is one that is re-evaluated whenever the check is resolved, with no caching of results taking place.

Realtime checks are useful when the accuracy of the check needs to be very high or where the check itself is inexpensive.

Takes the following parameters:

• check-name: a keyword representing the name of the check
• check-fn: an arity-2 function, with the first argument being a context map as provided during evaluation or at maintenance pipeline construction and the second argument being a callback function which should be called with the result fo the check to signal the check is complete; note, check functions must be non-blocking.
• opts: an optional map of additional options for the check, containing:
  • :timeout: a [[salutem.time/duration]] representing the amount of time to wait for the check to complete before considering it failed, defaulting to 10 seconds

realtime? clj

(realtime? check)

Returns true if the provided check is a realtime check, false otherwise.