Metrics
SmallRye Fault Tolerance provides support for MicroProfile Metrics and Micrometer. Alternatively, metrics may be completely disabled at the integration level.
As usual, this integration is based on CDI.
SmallRye Fault Tolerance includes an internal interface MetricsProvider and 3 different implementations.
Exactly 1 bean of type MetricsProvider must exist.
An instance of that bean is used to interact with the metrics system.
There are 2 ways to select which metrics provider bean exists:
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using a constructor of the Portable Extension,
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altering the set of discovered types.
Using a FaultToleranceExtension Constructor
In case the integrator uses the CDI Portable Extension FaultToleranceExtension and creates its instance manually, they can use a constructor.
In addition to a zero-parameter constructor, there’s a constructor that takes a MetricsIntegration parameter.
MetricsIntegration is an enum with these values:
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MICROPROFILE_METRICS: use MicroProfile Metrics integration -
MICROMETER: use Micrometer integration -
NOOP: no metrics
As mentioned above, this is only useful if the integrator creates an instance of the extension themselves.
If the integrator relies on the CDI container to discover and instantiate the extension, the zero-parameter constructor is used, which defaults to MICROPROFILE_METRICS.
Such integrator can use the 2nd approach of altering the set of discovered types.
Altering the Set of Discovered Types
The integrator may select the metrics provider by making sure that the correct implementation is discovered during CDI type discovery. The existing metrics providers are:
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io.smallrye.faulttolerance.metrics.MicroProfileMetricsProvider -
io.smallrye.faulttolerance.metrics.MicrometerProvider -
io.smallrye.faulttolerance.metrics.NoopProvider
| Only the names of the classes listed above are treated as public. That is, the classes should be treated as opaque, no guarantees about their internals are made. |
Exactly one of these classes must be discovered during CDI type discovery.
Integrators that rely on the CDI container to instantiate FaultToleranceExtension must be aware that in this case, the extension adds MicroProfileMetricsProvider to the set of discovered types.
If they want to use a different metrics provider, they need to veto the MicroProfileMetricsProvider type.
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Metrics Providers
Metrics providers have additional requirements, as described below.
MicroProfile Metrics
If MicroProfile Metrics are used, the integrator must ensure that the following artifacts are present:
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org.eclipse.microprofile.metrics:microprofile-metrics-api; -
some implementation of MicroProfile Metrics.