org.apache.hc.client5.http.observation

Class HttpClientObservationSupport

java.lang.Object

org.apache.hc.client5.http.observation.HttpClientObservationSupport

public final class HttpClientObservationSupport
extends Object

Utility class that wires Micrometer / OpenTelemetry instrumentation into the HttpClient execution pipeline(s).

This helper can install:

• Observations (via Micrometer ObservationRegistry) which can be bridged to OpenTelemetry tracing, and
• Metrics (via Micrometer MeterRegistry) such as per-request latency timers, response counters, I/O counters, and connection pool gauges.

Optional dependencies

Micrometer and OpenTelemetry are optional dependencies. Use the overloads that accept explicit registries (recommended) or the convenience overloads that use Metrics.globalRegistry. When Micrometer is not on the classpath, only the observation / metric features you actually call will be required.

Typical usage (classic client)

 ObservationRegistry obs = ObservationRegistry.create();
 MeterRegistry meters = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT);
 HttpClientBuilder b = HttpClients.custom();

 HttpClientObservationSupport.enable(
     b, obs, meters,
     ObservingOptions.DEFAULT,
     MetricConfig.DEFAULT);

 CloseableHttpClient client = b.build();
 

What gets installed

• An observation interceptor (if obsReg is non-null) that surrounds each execution with a start/stop span.
• Metric interceptors according to ObservingOptions.MetricSet: BASIC (latency timer + response counter), IO (bytes in/out counters), and CONN_POOL (pool gauges; classic and async variants).

Thread safety: This class is stateless. Methods may be called from any thread before the client is built.

Since:

5.6

Method Summary

Modifier and Type	Method and Description
static void	enable(CachingHttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg) Enables observations and default metrics on a caching async client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.
static void	enable(CachingHttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts) Enables observations and metrics on a caching async client builder with an explicit meter registry and default MetricConfig.
static void	enable(CachingHttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts, MetricConfig mc) Enables observations and metrics on a caching async client builder using explicit registries and MetricConfig.
static void	enable(CachingHttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, ObservingOptions opts) Enables observations and metrics on a caching async client builder using Metrics.globalRegistry and a custom ObservingOptions.
static void	enable(CachingHttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg) Enables observations and default metrics on a caching classic client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.
static void	enable(CachingHttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts) Enables observations and metrics on a caching classic client builder with an explicit meter registry and default MetricConfig.
static void	enable(CachingHttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts, MetricConfig mc) Enables observations and metrics on a caching classic client builder using explicit registries and MetricConfig.
static void	enable(CachingHttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, ObservingOptions opts) Enables observations and metrics on a caching classic client builder using Metrics.globalRegistry and a custom ObservingOptions.
static void	enable(HttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg) Enables observations and default metrics on an async client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.
static void	enable(HttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts) Enables observations and metrics on an async client builder with an explicit meter registry and default MetricConfig.
static void	enable(HttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts, MetricConfig mc) Enables observations and metrics on an async client builder using explicit registries and MetricConfig.
static void	enable(HttpAsyncClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, ObservingOptions opts) Enables observations and metrics on an async client builder using Metrics.globalRegistry and a custom ObservingOptions.
static void	enable(HttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg) Enables observations and default metrics on a classic client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.
static void	enable(HttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts) Enables observations and metrics on a classic client builder with an explicit meter registry and default MetricConfig.
static void	enable(HttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, io.micrometer.core.instrument.MeterRegistry meterReg, ObservingOptions opts, MetricConfig mc) Enables observations and metrics on a classic client builder using explicit registries and MetricConfig.
static void	enable(HttpClientBuilder builder, io.micrometer.observation.ObservationRegistry obsReg, ObservingOptions opts) Enables observations and metrics on a classic client builder using Metrics.globalRegistry and a custom ObservingOptions.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

enable

public static void enable(HttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg)

Enables observations and default metrics on a classic client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.

Parameters:

builder - client builder to instrument

obsReg - observation registry; if null no observations are installed

Since:

5.6

enable

public static void enable(HttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          ObservingOptions opts)

Enables observations and metrics on a classic client builder using Metrics.globalRegistry and a custom ObservingOptions.

Parameters:

builder - client builder to instrument

obsReg - observation registry; if null no observations are installed

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(HttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts)

Enables observations and metrics on a classic client builder with an explicit meter registry and default MetricConfig.

Parameters:

builder - client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(HttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts,
                          MetricConfig mc)

Enables observations and metrics on a classic client builder using explicit registries and MetricConfig.

Installs interceptors at the beginning of the execution chain.

Parameters:

builder - client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with (must not be null)

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

mc - metric configuration; when null MetricConfig.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg)

Enables observations and default metrics on a caching classic client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.

Parameters:

builder - caching client builder to instrument

obsReg - observation registry; if null no observations are installed

Since:

5.6

enable

public static void enable(CachingHttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          ObservingOptions opts)

Enables observations and metrics on a caching classic client builder using Metrics.globalRegistry and a custom ObservingOptions.

Parameters:

builder - caching client builder to instrument

obsReg - observation registry; if null no observations are installed

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts)

Enables observations and metrics on a caching classic client builder with an explicit meter registry and default MetricConfig.

Parameters:

builder - caching client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts,
                          MetricConfig mc)

Enables observations and metrics on a caching classic client builder using explicit registries and MetricConfig.

Interceptors are installed after the caching element so that metrics/observations reflect the actual exchange.

Parameters:

builder - caching client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with (must not be null)

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

mc - metric configuration; when null MetricConfig.DEFAULT is used

Since:

5.6

enable

public static void enable(HttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg)

Enables observations and default metrics on an async client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.

Parameters:

builder - async client builder to instrument

obsReg - observation registry; if null no observations are installed

Since:

5.6

enable

public static void enable(HttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          ObservingOptions opts)

Enables observations and metrics on an async client builder using Metrics.globalRegistry and a custom ObservingOptions.

Parameters:

builder - async client builder to instrument

obsReg - observation registry; if null no observations are installed

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(HttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts)

Enables observations and metrics on an async client builder with an explicit meter registry and default MetricConfig.

Parameters:

builder - async client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(HttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts,
                          MetricConfig mc)

Enables observations and metrics on an async client builder using explicit registries and MetricConfig.

Parameters:

builder - async client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with (must not be null)

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

mc - metric configuration; when null MetricConfig.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg)

Enables observations and default metrics on a caching async client builder using Metrics.globalRegistry and MetricConfig.DEFAULT.

Parameters:

builder - caching async client builder to instrument

obsReg - observation registry; if null no observations are installed

Since:

5.6

enable

public static void enable(CachingHttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          ObservingOptions opts)

Enables observations and metrics on a caching async client builder using Metrics.globalRegistry and a custom ObservingOptions.

Parameters:

builder - caching async client builder to instrument

obsReg - observation registry; if null no observations are installed

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts)

Enables observations and metrics on a caching async client builder with an explicit meter registry and default MetricConfig.

Parameters:

builder - caching async client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

Since:

5.6

enable

public static void enable(CachingHttpAsyncClientBuilder builder,
                          io.micrometer.observation.ObservationRegistry obsReg,
                          io.micrometer.core.instrument.MeterRegistry meterReg,
                          ObservingOptions opts,
                          MetricConfig mc)

Enables observations and metrics on a caching async client builder using explicit registries and MetricConfig.

Interceptors are installed after the caching element.

Parameters:

builder - caching async client builder to instrument

obsReg - observation registry; if null no observations are installed

meterReg - meter registry to register meters with (must not be null)

opts - observation/metric options; when null ObservingOptions.DEFAULT is used

mc - metric configuration; when null MetricConfig.DEFAULT is used

Since:

5.6