HealthIndicator<T extends Object> class abstract

Base class for health indicators that check service dependencies.

Health indicators are used by the health check system to determine whether the server is ready to handle requests. Each indicator checks a specific dependency (database, Redis, external service, etc.).

The type parameter T specifies the type of observedValue that this indicator produces, providing type safety when creating results.

Example implementation:

class MyServiceHealthIndicator extends HealthIndicator<double> {
  @override
  String get name => 'myservice:connection';

  @override
  String get componentType => HealthComponentType.component.name;

  @override
  String get observedUnit => 'ms';

  @override
  Future<HealthCheckResult> check() async {
    final stopwatch = Stopwatch()..start();
    try {
      await myService.ping();
      stopwatch.stop();
      return pass(observedValue: stopwatch.elapsedMilliseconds.toDouble());
    } catch (e) {
      return fail(output: 'Connection failed: $e');
    }
  }
}
Implementers

Constructors

HealthIndicator()
Const ctor to allow subclasses the same
const

Properties

componentId → String?
Unique identifier for the component instance.
no setter
componentType → String?
Type of the component.
no setter
hashCode → int
The hash code for this object.
no setterinherited
name → String
Human-readable name for this indicator.
no setter
observedUnit → String?
Unit of the observed value, e.g., ms, percent, bytes.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
timeout → Duration
Maximum time to wait for this check before considering it failed.
no setter

Methods

check() → Future<HealthCheckResult>
Perform the health check and return the result.
fail({T? observedValue, String? output, DateTime? time}) → HealthCheckResult
Creates a failing health check result for this indicator.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
pass({T? observedValue, String? output, DateTime? time}) → HealthCheckResult
Creates a passing health check result for this indicator.
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited