\Drupal\strata\Health TripwireInterface

A single health check that asserts a SYMPTOM rather than a cause.

Each implementation corresponds to a failure mode that has actually occurred. One that never fires still costs a check on every sweep.

Three rules bind every implementation:

It asserts a symptom, not a cause. "This frame's digest does not match its bytes" is a tripwire; "the storage provider is misconfigured" is a conclusion, and a conclusion drawn from one observation is how a health system starts reporting confident nonsense.
It must be O(1) or explicitly bounded. No full-table scans on the request path, and no going looking for data the caller did not already have - that is how a cheap check turns into a query that runs on every request.
It must never repair anything. Detection and repair are separated so a repair can be gated, rate-limited and escalated independently of whatever noticed, and so a check stays safe to run from anywhere.

Summary

Methods

Constants

code()
check()

No public constants found

File: src/Health/TripwireInterface.php
Package: \Application
See also

Methods

code()

code() : string

The stable dotted code every finding from this tripwire reports under.

The code is the key the registry, the circuit breaker and the ledger all use, so it has to outlive refactors of the class that produces it. Rename the class freely; never the code.

Returns

string —

For example "frame.digest_mismatch".

check()

check(array  $observation) : \Drupal\strata\Health\Finding|null

Evaluates the check against one observation.

Parameters

array

$observation

Scalars the caller already had in hand. A tripwire reads from this and nothing else.

Returns

\Drupal\strata\Health\Finding|null —

A finding when the symptom is present, or NULL when the check is satisfied.