### Build and Start HTTPServer

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/httpserver/HTTPServer.Builder.html

Initializes the server with the configured settings and starts the underlying HTTP or HTTPS server.

```java
public HTTPServer buildAndStart() throws IOException {
  if (registry == null) {
    registry = PrometheusRegistry.defaultRegistry;
  }
  HttpServer httpServer;
  if (httpsConfigurator != null) {
    httpServer = HttpsServer.create(makeInetSocketAddress(), 3);
    ((HttpsServer) httpServer).setHttpsConfigurator(httpsConfigurator);
  } else {
    httpServer = HttpServer.create(makeInetSocketAddress(), 3);
  }
  ExecutorService executorService = makeExecutorService();
  httpServer.setExecutor(executorService);
  return new HTTPServer(
      config,
      executorService,
      httpServer,
      registry,
      authenticator,
      authenticatedSubjectAttributeName,
      defaultHandler,
      metricsHandlerPath,
      registerHealthHandler);
}
```

--------------------------------

### Initialize and start HTTPServer

Source: https://prometheus.github.io/client_java/exporters/httpserver

Creates and starts a standalone server instance on a specified port.

```java
HTTPServer server = HTTPServer.builder()
  .port(9400)
  .buildAndStart();
```

--------------------------------

### buildAndStart()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/exporter/opentelemetry/OpenTelemetryExporter.Builder.html

Builds and starts the exporter.

```APIDOC
## buildAndStart()

### Description
Finalizes the configuration and starts the OpenTelemetry exporter.

### Signature
`public OpenTelemetryExporter buildAndStart()`
```

--------------------------------

### Generic Cache Metrics Example

Source: https://prometheus.github.io/client_java/instrumentation/caffeine

Example output for standard cache metrics available for all instances.

```text
# TYPE caffeine_cache_hit counter
# HELP caffeine_cache_hit Cache hit totals
caffeine_cache_hit_total{cache="mycache"} 10.0
# TYPE caffeine_cache_miss counter
# HELP caffeine_cache_miss Cache miss totals
caffeine_cache_miss_total{cache="mycache"} 3.0
# TYPE caffeine_cache_requests counter
# HELP caffeine_cache_requests Cache request totals, hits + misses
caffeine_cache_requests_total{cache="mycache"} 13.0
# TYPE caffeine_cache_eviction counter
# HELP caffeine_cache_eviction Cache eviction totals, doesn't include manually removed entries
caffeine_cache_eviction_total{cache="mycache"} 1.0
# TYPE caffeine_cache_estimated_size
# HELP caffeine_cache_estimated_size Estimated cache size
caffeine_cache_estimated_size{cache="mycache"} 5.0
```

--------------------------------

### Start an HTTPServer

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/exporter/httpserver/HTTPServer.html

Initialize and start a new HTTPServer instance on a specified port using the builder pattern.

```java
HTTPServer server = HTTPServer.builder()
    .port(9090)
    .buildAndStart();
```

--------------------------------

### HTTPServer Initialization

Source: https://prometheus.github.io/client_java/exporters/httpserver

How to instantiate and start the HTTPServer using the builder pattern.

```APIDOC
## HTTPServer Initialization

### Description
Initializes and starts a standalone HTTPServer instance to expose metrics.

### Usage
```java
HTTPServer server = HTTPServer.builder()
  .port(9400)
  .buildAndStart();
```
```

--------------------------------

### buildAndStart()

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/opentelemetry/OpenTelemetryExporter.Builder.html

Constructs and starts the OpenTelemetryExporter instance.

```APIDOC
## buildAndStart()

### Description
Finalizes the configuration and returns a started OpenTelemetryExporter instance.
```

--------------------------------

### HTTPServer.builder()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/exporter/httpserver/HTTPServer.html

Creates a new builder instance to configure and start the HTTPServer.

```APIDOC
## static HTTPServer.Builder builder()

### Description
Creates a new builder instance for configuring the HTTPServer.

### Signature
`public static HTTPServer.Builder builder()`
```

--------------------------------

### Example Exported Metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmCompilationMetrics.html

Sample output format for the jvm_compilation_time_seconds_total metric.

```text
# HELP jvm_compilation_time_seconds_total The total time in seconds taken for HotSpot class compilation
# TYPE jvm_compilation_time_seconds_total counter
jvm_compilation_time_seconds_total 0.152
```

--------------------------------

### Initialize Info Metric Builder

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/core/metrics/Info.Builder.html

Shows the start of an Info metric builder initialization.

```java
Info info1 = Info.builder()
```

--------------------------------

### Loading Cache Metrics Example

Source: https://prometheus.github.io/client_java/instrumentation/caffeine

Metrics available specifically for LoadingCache instances.

```text
# TYPE caffeine_cache_load_failure counter
# HELP caffeine_cache_load_failure Cache load failures
caffeine_cache_load_failure_total{cache="mycache"} 10.0
# TYPE caffeine_cache_loads counter
# HELP caffeine_cache_loads Cache loads: both success and failures
caffeine_cache_loads_total{cache="mycache"} 3.0
# TYPE caffeine_cache_load_duration_seconds summary
# HELP caffeine_cache_load_duration_seconds Cache load duration: both success and failures
caffeine_cache_load_duration_seconds_count{cache="mycache"} 7.0
caffeine_cache_load_duration_seconds_sum{cache="mycache"} 0.0034
```

--------------------------------

### Example Exported Metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmGarbageCollectorMetrics.html

Sample output format for JVM garbage collection metrics.

```text
# HELP jvm_gc_collection_seconds Time spent in a given JVM garbage collector in seconds.
# TYPE jvm_gc_collection_seconds summary
jvm_gc_collection_seconds_count{gc="PS MarkSweep"} 0
jvm_gc_collection_seconds_sum{gc="PS MarkSweep"} 0.0
jvm_gc_collection_seconds_count{gc="PS Scavenge"} 0
jvm_gc_collection_seconds_sum{gc="PS Scavenge"} 0.0
```

--------------------------------

### Example Exported Metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/ProcessMetrics.html

Sample output format for process metrics exported by the library.

```text
# HELP process_cpu_seconds_total Total user and system CPU time spent in seconds.
# TYPE process_cpu_seconds_total counter
process_cpu_seconds_total 1.63
# HELP process_max_fds Maximum number of open file descriptors.
# TYPE process_max_fds gauge
process_max_fds 524288.0
# HELP process_open_fds Number of open file descriptors.
# TYPE process_open_fds gauge
process_open_fds 28.0
# HELP process_resident_memory_bytes Resident memory size in bytes.
# TYPE process_resident_memory_bytes gauge
process_resident_memory_bytes 7.8577664E7
# HELP process_start_time_seconds Start time of the process since unix epoch in seconds.
# TYPE process_start_time_seconds gauge
process_start_time_seconds 1.693829439767E9
# HELP process_virtual_memory_bytes Virtual memory size in bytes.
# TYPE process_virtual_memory_bytes gauge
process_virtual_memory_bytes 1.2683624448E10
```

--------------------------------

### Example exported metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmMemoryPoolAllocationMetrics.html

Sample output of the jvm_memory_pool_allocated_bytes_total counter metrics.

```text
# HELP jvm_memory_pool_allocated_bytes_total Total bytes allocated in a given JVM memory pool. Only updated after GC, not continuously.
# TYPE jvm_memory_pool_allocated_bytes_total counter
jvm_memory_pool_allocated_bytes_total{pool="Code Cache"} 4336448.0
jvm_memory_pool_allocated_bytes_total{pool="Compressed Class Space"} 875016.0
jvm_memory_pool_allocated_bytes_total{pool="Metaspace"} 7480456.0
jvm_memory_pool_allocated_bytes_total{pool="PS Eden Space"} 1.79232824E8
jvm_memory_pool_allocated_bytes_total{pool="PS Old Gen"} 1428888.0
jvm_memory_pool_allocated_bytes_total{pool="PS Survivor Space"} 4115280.0
```

--------------------------------

### Histogram Usage Example

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/metrics/Histogram.html

Demonstrates how to build, register, and observe values with a Histogram metric.

```java
Histogram histogram = Histogram.builder()
        .name("http_request_duration_seconds")
        .help("HTTP request service time in seconds")
        .unit(SECONDS)
        .labelNames("method", "path", "status_code")
        .register();

long start = System.nanoTime();
// do something
histogram.labelValues("GET", "/", "200").observe(Unit.nanosToSeconds(System.nanoTime() - start));
```

--------------------------------

### Exposition format for initialized metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/metrics/StatefulMetric.html

Shows the expected output when metrics are initialized with a zero value at application start.

```text
payment_transactions_total{payment_type="credit card"} 0.0
payment_transactions_total{payment_type="paypal"} 0.0
```

--------------------------------

### nameMustStartWith(Collection<String> prefixes)

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/model/registry/MetricNameFilter.Builder.html

Includes only samples whose names start with one of the provided prefixes.

```APIDOC
### Method
`public Builder nameMustStartWith(@Nullable Collection<String> prefixes)`

### Description
Restricts inclusion to samples starting with one of the specified prefixes. Empty input means no restriction is applied.
```

--------------------------------

### Configure Summary Quantiles

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/core/metrics/Summary.html

Examples for adding quantiles to a Summary metric, including standard usage and special cases for min/max values.

```java
.quantile(0.95, 0.001)
```

```java
.quantile(0.0, 0.0)
```

```java
.quantile(1.0, 0.0)
```

--------------------------------

### Build and Start Exporter

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/opentelemetry/OpenTelemetryExporter.Builder.html

Initializes the OpenTelemetryExporter using the configured settings and the default registry if none is provided.

```java
public OpenTelemetryExporter buildAndStart() {
  if (registry == null) {
    registry = PrometheusRegistry.defaultRegistry;
  }
  return new OpenTelemetryExporter(OtelAutoConfig.createReader(this, config, registry));
}
```

--------------------------------

### Example Metric Output

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/guava/CacheMetricsCollector.html

Shows the format of metrics exported for a monitored Guava cache.

```text
guava_cache_hit_total{cache="mycache"} 10.0
guava_cache_miss_total{cache="mycache"} 3.0
guava_cache_requests_total{cache="mycache"} 13.0
guava_cache_eviction_total{cache="mycache"} 1.0
guava_cache_size{cache="mycache"} 5.0
```

--------------------------------

### Weighted Cache Metrics Example

Source: https://prometheus.github.io/client_java/instrumentation/caffeine

Metrics available for caches configured with a weigher.

```text
# TYPE caffeine_cache_eviction_weight counter
# HELP caffeine_cache_eviction_weight Weight of evicted cache entries, doesn't include manually removed entries

caffeine_cache_eviction_weight_total{cache="mycache"} 5.0
# TYPE caffeine_cache_weighted_size gauge
# HELP caffeine_cache_weighted_size Approximate accumulated weight of cache entries
caffeine_cache_weighted_size{cache="mycache"} 30.0
```

--------------------------------

### Example Exported Metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmClassLoadingMetrics.html

Sample output showing the gauge and counter metrics exported by the class.

```text
# HELP jvm_classes_currently_loaded The number of classes that are currently loaded in the JVM
# TYPE jvm_classes_currently_loaded gauge
jvm_classes_currently_loaded 1109.0
# HELP jvm_classes_loaded_total The total number of classes that have been loaded since the JVM has started execution
# TYPE jvm_classes_loaded_total counter
jvm_classes_loaded_total 1109.0
# HELP jvm_classes_unloaded_total The total number of classes that have been unloaded since the JVM has started execution
# TYPE jvm_classes_unloaded_total counter
jvm_classes_unloaded_total 0.0
```

--------------------------------

### Configure HTTPServer Builder Options

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/httpserver/HTTPServer.Builder.html

Methods for customizing the HTTPServer instance before it is built and started.

```java
public Builder httpsConfigurator(HttpsConfigurator configurator) {
  this.httpsConfigurator = configurator;
  return this;
}
```

```java
public Builder defaultHandler(HttpHandler defaultHandler) {
  this.defaultHandler = defaultHandler;
  return this;
}
```

```java
public Builder metricsHandlerPath(String metricsHandlerPath) {
  this.metricsHandlerPath = metricsHandlerPath;
  return this;
}
```

```java
public Builder registerHealthHandler(boolean registerHealthHandler) {
  this.registerHealthHandler = registerHealthHandler;
  return this;
}
```

--------------------------------

### Environment Variable to Property Mapping

Source: https://prometheus.github.io/client_java/config/config

Examples of mapping environment variables to their corresponding property names.

```text
IO_PROMETHEUS_METRICS_EXEMPLARS_ENABLED -> io.prometheus.metrics.exemplars_enabled
IO_PROMETHEUS_EXPORTER_HTTP_SERVER_PORT -> io.prometheus.exporter.http_server.port
IO_PROMETHEUS_METRICS_HISTOGRAM_NATIVE_ONLY -> io.prometheus.metrics.histogram_native_only
```

--------------------------------

### Configure HTTP Server Port via Properties

Source: https://prometheus.github.io/client_java/config/config

Example of setting the HTTPServer port using a properties file format.

```properties
io.prometheus.exporter.http_server.port=9401
```

--------------------------------

### Initialize MetricsProperties Builder

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/config/MetricsProperties.Builder.html

Use the static builder method to start configuring metrics properties.

```java
public static Builder builder() {
    return new Builder();
  }
```

--------------------------------

### Start Application with OpenTelemetry Agent

Source: https://prometheus.github.io/client_java/otel/tracing

Attach the OpenTelemetry Java agent to your application at startup to enable distributed tracing.

```bash
java -javaagent:path/to/opentelemetry-javaagent.jar -jar myapp.jar
```

--------------------------------

### Example Loader Metrics Output

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.html

Additional metrics provided when the cache includes a loader.

```text
    caffeine_cache_load_failure_total{cache="mycache"} 2.0
    caffeine_cache_loads_total{cache="mycache"} 7.0
    caffeine_cache_load_duration_seconds_count{cache="mycache"} 7.0
    caffeine_cache_load_duration_seconds_sum{cache="mycache"} 0.0034
```

--------------------------------

### Initialize Prometheus Java Application

Source: https://prometheus.github.io/client_java/getting-started/quickstart

Sets up JVM metrics, registers a custom counter, and starts an HTTP server on port 9400.

```java
import io.prometheus.metrics.core.metrics.Counter;
import io.prometheus.metrics.exporter.httpserver.HTTPServer;
import io.prometheus.metrics.instrumentation.jvm.JvmMetrics;

import java.io.IOException;

public class App {

    public static void main(String[] args) throws InterruptedException, IOException {

        JvmMetrics.builder().register(); // initialize the out-of-the-box JVM metrics

        Counter counter = Counter.builder()
                .name("my_count_total")
                .help("example counter")
                .labelNames("status")
                .register();

        counter.labelValues("ok").inc();
        counter.labelValues("ok").inc();
        counter.labelValues("error").inc();

        HTTPServer server = HTTPServer.builder()
                .port(9400)
                .buildAndStart();

        System.out.println("HTTPServer listening on port http://localhost:" +
          server.getPort() + "/metrics");

        Thread.currentThread().join(); // sleep forever
    }
}
```

--------------------------------

### Example Exported Metrics

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmMemoryMetrics.html

Sample output of JVM memory metrics exported in Prometheus format.

```text
# HELP jvm_memory_committed_bytes Committed (bytes) of a given JVM memory area.
# TYPE jvm_memory_committed_bytes gauge
jvm_memory_committed_bytes{area="heap"} 4.98597888E8
jvm_memory_committed_bytes{area="nonheap"} 1.1993088E7
# HELP jvm_memory_init_bytes Initial bytes of a given JVM memory area.
# TYPE jvm_memory_init_bytes gauge
jvm_memory_init_bytes{area="heap"} 5.20093696E8
jvm_memory_init_bytes{area="nonheap"} 2555904.0
# HELP jvm_memory_max_bytes Max (bytes) of a given JVM memory area.
# TYPE jvm_memory_max_bytes gauge
jvm_memory_max_bytes{area="heap"} 7.38983936E9
jvm_memory_max_bytes{area="nonheap"} -1.0
# HELP jvm_memory_objects_pending_finalization The number of objects waiting in the finalizer queue.
# TYPE jvm_memory_objects_pending_finalization gauge
jvm_memory_objects_pending_finalization 0.0
# HELP jvm_memory_pool_collection_committed_bytes Committed after last collection bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_collection_committed_bytes gauge
jvm_memory_pool_collection_committed_bytes{pool="PS Eden Space"} 1.30023424E8
jvm_memory_pool_collection_committed_bytes{pool="PS Old Gen"} 3.47078656E8
jvm_memory_pool_collection_committed_bytes{pool="PS Survivor Space"} 2.1495808E7
```

--------------------------------

### Implement a Batch Job with Pushgateway

Source: https://prometheus.github.io/client_java/exporters/pushgateway

Example of a batch job that registers a gauge and pushes metrics to the Pushgateway upon completion.

```java
public class ExampleBatchJob {

    private static PushGateway pushGateway = PushGateway.builder()
            .address("localhost:9091") // not needed as localhost:9091 is the default
            .job("example")
            .build();

    private static Gauge dataProcessedInBytes = Gauge.builder()
            .name("data_processed")
            .help("data processed in the last batch job run")
            .unit(Unit.BYTES)
            .register();

    public static void main(String[] args) throws Exception {
        try {
            long bytesProcessed = processData();
            dataProcessedInBytes.set(bytesProcessed);
        } finally {
            pushGateway.push();
        }
    }

    public static long processData() {
        // Imagine a batch job here that processes data
        // and returns the number of Bytes processed.
        return 42;
    }
}
```

--------------------------------

### Example Metrics Output

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmNativeMemoryMetrics.html

Sample output showing the exported gauge metrics for committed and reserved native memory.

```text
# HELP jvm_native_memory_committed_bytes Committed bytes of a given JVM. Committed memory represents the amount of memory the JVM is using right now.
# TYPE jvm_native_memory_committed_bytes gauge
jvm_native_memory_committed_bytes{pool="Arena Chunk"} 58480.0
jvm_native_memory_committed_bytes{pool="Arguments"} 25119.0
jvm_native_memory_committed_bytes{pool="Class"} 1.00609438E8
jvm_native_memory_committed_bytes{pool="Code"} 2.7980888E7
jvm_native_memory_committed_bytes{pool="Compiler"} 529922.0
jvm_native_memory_committed_bytes{pool="GC"} 515466.0
jvm_native_memory_committed_bytes{pool="Internal"} 673194.0
jvm_native_memory_committed_bytes{pool="Java Heap"} 4.0923136E7
jvm_native_memory_committed_bytes{pool="Logging"} 4596.0
jvm_native_memory_committed_bytes{pool="Module"} 96408.0
jvm_native_memory_committed_bytes{pool="Native Memory Tracking"} 3929432.0
jvm_native_memory_committed_bytes{pool="Other"} 667656.0
jvm_native_memory_committed_bytes{pool="Safepoint"} 8192.0
jvm_native_memory_committed_bytes{pool="Symbol"} 2.4609808E7
jvm_native_memory_committed_bytes{pool="Synchronizer"} 272520.0
jvm_native_memory_committed_bytes{pool="Thread"} 3546896.0
jvm_native_memory_committed_bytes{pool="Total"} 2.0448392E8
jvm_native_memory_committed_bytes{pool="Tracing"} 1.0
jvm_native_memory_committed_bytes{pool="Unknown"} 32768.0
# HELP jvm_native_memory_reserved_bytes Reserved bytes of a given JVM. Reserved memory represents the total amount of memory the JVM can potentially use.
# TYPE jvm_native_memory_reserved_bytes gauge
jvm_native_memory_reserved_bytes{pool="Arena Chunk"} 25736.0
jvm_native_memory_reserved_bytes{pool="Arguments"} 25119.0
jvm_native_memory_reserved_bytes{pool="Class"} 1.162665374E9
jvm_native_memory_reserved_bytes{pool="Code"} 2.55386712E8
jvm_native_memory_reserved_bytes{pool="Compiler"} 529922.0
jvm_native_memory_reserved_bytes{pool="GC"} 1695114.0
jvm_native_memory_reserved_bytes{pool="Internal"} 673191.0
jvm_native_memory_reserved_bytes{pool="Java Heap"} 4.02653184E8
jvm_native_memory_reserved_bytes{pool="Logging"} 4596.0
jvm_native_memory_reserved_bytes{pool="Module"} 96408.0
jvm_native_memory_reserved_bytes{pool="Native Memory Tracking"} 3929400.0
jvm_native_memory_reserved_bytes{pool="Other"} 667656.0
jvm_native_memory_reserved_bytes{pool="Safepoint"} 8192.0
jvm_native_memory_reserved_bytes{pool="Symbol"} 2.4609808E7
jvm_native_memory_reserved_bytes{pool="Synchronizer"} 272520.0
jvm_native_memory_reserved_bytes{pool="Thread"} 3.383272E7
jvm_native_memory_reserved_bytes{pool="Total"} 1.887108421E9
jvm_native_memory_reserved_bytes{pool="Tracing"} 1.0
jvm_native_memory_reserved_bytes{pool="Unknown"} 32768.0
```

--------------------------------

### Example JVM Memory Metrics Output

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/jvm/JvmMemoryMetrics.Builder.html

Sample output showing various JVM memory metrics exported by the instrumentation.

```text
# HELP jvm_memory_committed_bytes Committed (bytes) of a given JVM memory area.
# TYPE jvm_memory_committed_bytes gauge
jvm_memory_committed_bytes{area="heap"} 4.98597888E8
jvm_memory_committed_bytes{area="nonheap"} 1.1993088E7
# HELP jvm_memory_init_bytes Initial bytes of a given JVM memory area.
# TYPE jvm_memory_init_bytes gauge
jvm_memory_init_bytes{area="heap"} 5.20093696E8
jvm_memory_init_bytes{area="nonheap"} 2555904.0
# HELP jvm_memory_max_bytes Max (bytes) of a given JVM memory area.
# TYPE jvm_memory_max_bytes gauge
jvm_memory_max_bytes{area="heap"} 7.38983936E9
jvm_memory_max_bytes{area="nonheap"} -1.0
# HELP jvm_memory_objects_pending_finalization The number of objects waiting in the finalizer queue.
# TYPE jvm_memory_objects_pending_finalization gauge
jvm_memory_objects_pending_finalization 0.0
# HELP jvm_memory_pool_collection_committed_bytes Committed after last collection bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_collection_committed_bytes gauge
jvm_memory_pool_collection_committed_bytes{pool="PS Eden Space"} 1.30023424E8
jvm_memory_pool_collection_committed_bytes{pool="PS Old Gen"} 3.47078656E8
jvm_memory_pool_collection_committed_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_collection_init_bytes Initial after last collection bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_collection_init_bytes gauge
jvm_memory_pool_collection_init_bytes{pool="PS Eden Space"} 1.30023424E8
jvm_memory_pool_collection_init_bytes{pool="PS Old Gen"} 3.47078656E8
jvm_memory_pool_collection_init_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_collection_max_bytes Max bytes after last collection of a given JVM memory pool.
# TYPE jvm_memory_pool_collection_max_bytes gauge
jvm_memory_pool_collection_max_bytes{pool="PS Eden Space"} 2.727870464E9
jvm_memory_pool_collection_max_bytes{pool="PS Old Gen"} 5.542248448E9
jvm_memory_pool_collection_max_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_collection_used_bytes Used bytes after last collection of a given JVM memory pool.
# TYPE jvm_memory_pool_collection_used_bytes gauge
jvm_memory_pool_collection_used_bytes{pool="PS Eden Space"} 0.0
jvm_memory_pool_collection_used_bytes{pool="PS Old Gen"} 1249696.0
jvm_memory_pool_collection_used_bytes{pool="PS Survivor Space"} 0.0
# HELP jvm_memory_pool_committed_bytes Committed bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_committed_bytes gauge
jvm_memory_pool_committed_bytes{pool="Code Cache"} 4128768.0
jvm_memory_pool_committed_bytes{pool="Compressed Class Space"} 917504.0
jvm_memory_pool_committed_bytes{pool="Metaspace"} 6946816.0
jvm_memory_pool_committed_bytes{pool="PS Eden Space"} 1.30023424E8
jvm_memory_pool_committed_bytes{pool="PS Old Gen"} 3.47078656E8
jvm_memory_pool_committed_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_init_bytes Initial bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_init_bytes gauge
jvm_memory_pool_init_bytes{pool="Code Cache"} 2555904.0
jvm_memory_pool_init_bytes{pool="Compressed Class Space"} 0.0
jvm_memory_pool_init_bytes{pool="Metaspace"} 0.0
jvm_memory_pool_init_bytes{pool="PS Eden Space"} 1.30023424E8
jvm_memory_pool_init_bytes{pool="PS Old Gen"} 3.47078656E8
jvm_memory_pool_init_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_max_bytes Max bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_max_bytes gauge
```

--------------------------------

### Example Cache Metrics Output

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/guava/CacheMetricsCollector.html

Sample output of metrics exposed by the collector for a cache named 'mycache'.

```text
    guava_cache_hit_total{cache="mycache"} 10.0
    guava_cache_miss_total{cache="mycache"} 3.0
    guava_cache_requests_total{cache="mycache"} 13.0
    guava_cache_eviction_total{cache="mycache"} 1.0
    guava_cache_size{cache="mycache"} 5.0
```

--------------------------------

### Configure Tail Sampling for Exemplars

Source: https://prometheus.github.io/client_java/otel/tracing

Example configuration for the OpenTelemetry collector to sample spans marked with the exemplar attribute.

```yaml
policies:
  [
    {
      name: keep-exemplars,
      type: string_attribute,
      string_attribute: { key: "exemplar", values: ["true"] },
    },
    { name: keep-10-percent, type: probabilistic, probabilistic: { sampling_percentage: 10 } },
  ]
```

--------------------------------

### Registering Process Metrics with GaugeWithCallback

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/jvm/ProcessMetrics.Builder.html

Examples of using GaugeWithCallback to register process-specific metrics like start time, file descriptors, and memory usage.

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_START_TIME_SECONDS)
    .help("Start time of the process since unix epoch in seconds.")
    .unit(Unit.SECONDS)
    .callback(callback -> callback.call(Unit.millisToSeconds(runtimeBean.getStartTime())))
    .constLabels(constLabels)
    .register(registry);
```

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_OPEN_FDS)
    .help("Number of open file descriptors.")
    .callback(
        callback -> {
          try {
            Long openFds = callLongGetter("getOpenFileDescriptorCount", osBean);
            if (openFds != null) {
              callback.call(openFds);
            }
          } catch (Exception ignored) {
            // Ignored
          }
        })
    .constLabels(constLabels)
    .register(registry);
```

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_MAX_FDS)
    .help("Maximum number of open file descriptors.")
    .callback(
        callback -> {
          try {
            Long maxFds = callLongGetter("getMaxFileDescriptorCount", osBean);
            if (maxFds != null) {
              callback.call(maxFds);
            }
          } catch (Exception ignored) {
            // Ignored
          }
        })
    .constLabels(constLabels)
    .register(registry);
```

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_VIRTUAL_MEMORY_BYTES)
    .help("Virtual memory size in bytes.")
    .unit(Unit.BYTES)
    .callback(
        callback -> {
          try {
            String line = grepper.lineStartingWith(PROC_SELF_STATUS, "VmSize:");
            callback.call(Unit.kiloBytesToBytes(Double.parseDouble(line.split("\\s+")[1])));
          } catch (Exception ignored) {
            // Ignored
          }
        })
    .constLabels(constLabels)
    .register(registry);
```

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_RESIDENT_MEMORY_BYTES)
    .help("Resident memory size in bytes.")
    .unit(Unit.BYTES)
    .callback(
        callback -> {
          try {
            String line = grepper.lineStartingWith(PROC_SELF_STATUS, "VmRSS:");
            callback.call(Unit.kiloBytesToBytes(Double.parseDouble(line.split("\\s+")[1])));
          } catch (Exception ignored) {
            // Ignored
          }
        })
    .constLabels(constLabels)
    .register(registry);
```

--------------------------------

### Example JVM Buffer Pool Metrics Output

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmBufferPoolMetrics.html

Sample output showing the exported gauge metrics for buffer pool capacity, used buffers, and used bytes.

```text
# HELP jvm_buffer_pool_capacity_bytes Bytes capacity of a given JVM buffer pool.
# TYPE jvm_buffer_pool_capacity_bytes gauge
jvm_buffer_pool_capacity_bytes{pool="direct"} 8192.0
jvm_buffer_pool_capacity_bytes{pool="mapped"} 0.0
# HELP jvm_buffer_pool_used_buffers Used buffers of a given JVM buffer pool.
# TYPE jvm_buffer_pool_used_buffers gauge
jvm_buffer_pool_used_buffers{pool="direct"} 1.0
jvm_buffer_pool_used_buffers{pool="mapped"} 0.0
# HELP jvm_buffer_pool_used_bytes Used bytes of a given JVM buffer pool.
# TYPE jvm_buffer_pool_used_bytes gauge
jvm_buffer_pool_used_bytes{pool="direct"} 8192.0
jvm_buffer_pool_used_bytes{pool="mapped"} 0.0
```

--------------------------------

### Example JVM Thread Metrics Output

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/instrumentation/jvm/JvmThreadsMetrics.html

Sample output showing the format and types of metrics exported by JvmThreadsMetrics.

```text
# HELP jvm_threads_current Current thread count of a JVM
# TYPE jvm_threads_current gauge
jvm_threads_current 10.0
# HELP jvm_threads_daemon Daemon thread count of a JVM
# TYPE jvm_threads_daemon gauge
jvm_threads_daemon 8.0
# HELP jvm_threads_deadlocked Cycles of JVM-threads that are in deadlock waiting to acquire object monitors or ownable synchronizers
# TYPE jvm_threads_deadlocked gauge
jvm_threads_deadlocked 0.0
# HELP jvm_threads_deadlocked_monitor Cycles of JVM-threads that are in deadlock waiting to acquire object monitors
# TYPE jvm_threads_deadlocked_monitor gauge
jvm_threads_deadlocked_monitor 0.0
# HELP jvm_threads_peak Peak thread count of a JVM
# TYPE jvm_threads_peak gauge
jvm_threads_peak 10.0
# HELP jvm_threads_started_total Started thread count of a JVM
# TYPE jvm_threads_started_total counter
jvm_threads_started_total 10.0
# HELP jvm_threads_state Current count of threads by state
# TYPE jvm_threads_state gauge
jvm_threads_state{state="BLOCKED"} 0.0
jvm_threads_state{state="NEW"} 0.0
jvm_threads_state{state="RUNNABLE"} 5.0
jvm_threads_state{state="TERMINATED"} 0.0
jvm_threads_state{state="TIMED_WAITING"} 2.0
jvm_threads_state{state="UNKNOWN"} 0.0
jvm_threads_state{state="WAITING"} 3.0
```

--------------------------------

### init()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/expositionformats/ExpositionFormats.html

Initializes the ExpositionFormats configuration.

```APIDOC
### public static ExpositionFormats init()

Initializes the ExpositionFormats configuration with default settings.
```

--------------------------------

### Prometheus Metric Text Format Example

Source: https://prometheus.github.io/client_java/getting-started/labels

An example of how a counter metric with labels appears in the Prometheus text format.

```text
# HELP payments_total total number of payments
# TYPE payments_total counter
payments_total{status="error",type="paypal"} 1.0
payments_total{status="success",type="credit card"} 3.0
payments_total{status="success",type="paypal"} 2.0

```

--------------------------------

### Register Process Start Time Gauge

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/jvm/ProcessMetrics.html

Registers a gauge to track the process start time in seconds since the Unix epoch.

```java
GaugeWithCallback.builder(config)
    .name(PROCESS_START_TIME_SECONDS)
    .help("Start time of the process since unix epoch in seconds.")
    .unit(Unit.SECONDS)
    .callback(callback -> callback.call(Unit.millisToSeconds(runtimeBean.getStartTime())))
    .constLabels(constLabels)
    .register(registry);
```

--------------------------------

### Initialize and Observe a Summary Metric

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/metrics/Summary.html

Configures a Summary metric with quantiles and records an observation using a timer.

```java
Summary summary = Summary.builder()
        .name("http_request_duration_seconds_hi")
        .help("HTTP request service time in seconds")
        .unit(SECONDS)
        .labelNames("method", "path", "status_code")
        .quantile(0.5, 0.01)
        .quantile(0.95, 0.001)
        .quantile(0.99, 0.001)
        .register();

long start = System.nanoTime();
// process a request, duration will be observed
summary.labelValues("GET", "/", "200").observe(Unit.nanosToSeconds(System.nanoTime() - start));
```

--------------------------------

### get()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/datapoints/CounterDataPoint.html

Retrieves the current value of the counter.

```APIDOC
## double get()

### Description
Returns the current value of the counter as a double.

### Returns
- (double) - The current counter value.
```

--------------------------------

### Initialize ExpositionFormats

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/expositionformats/ExpositionFormats.html

Use the init methods to create an instance of ExpositionFormats configured with Prometheus properties.

```java
public static ExpositionFormats init() {
    return init(PrometheusProperties.get());
  }

  @SuppressWarnings("deprecation")
  public static ExpositionFormats init(PrometheusProperties properties) {
    ExporterProperties exporterProps = properties.getExporterProperties();
    OpenMetrics2Properties om2Props = properties.getOpenMetrics2Properties();

    return new ExpositionFormats(
        new PrometheusProtobufWriter(),
        PrometheusTextFormatWriter.builder()
            .setIncludeCreatedTimestamps(exporterProps.getIncludeCreatedTimestamps())
            .setTimestampsInMs(exporterProps.getPrometheusTimestampsInMs())
            .build(),
        OpenMetricsTextFormatWriter.builder()
            .setCreatedTimestampsEnabled(exporterProps.getIncludeCreatedTimestamps())
            .setExemplarsOnAllMetricTypesEnabled(exporterProps.getExemplarsOnAllMetricTypes())
            .build(),
        OpenMetrics2TextFormatWriter.builder()
            .setOpenMetrics2Properties(om2Props)
            .setCreatedTimestampsEnabled(exporterProps.getIncludeCreatedTimestamps())
            .setExemplarsOnAllMetricTypesEnabled(exporterProps.getExemplarsOnAllMetricTypes())
            .build());
  }
```

--------------------------------

### Constructing Info Metrics

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/core/metrics/Info.Builder.html

Demonstrates how to use the Info.builder() to create Info metric instances.

```java
    *     .name("runtime_info")
    *     .build();
    * Info info2 = Info.builder()
    *     .name("runtime")
    *     .build();
    * }
```

--------------------------------

### init(PrometheusProperties properties)

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/expositionformats/ExpositionFormats.html

Initializes the ExpositionFormats configuration using provided properties.

```APIDOC
### public static ExpositionFormats init(PrometheusProperties properties)

Initializes the ExpositionFormats configuration using the specified PrometheusProperties.
```

--------------------------------

### Creating and Registering an Info Metric

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/metrics/Info.html

Demonstrates how to build and register an Info metric, then populate it with label values using system properties.

```java
Info info = Info.builder()
        .name("java_runtime_info")
        .help("Java runtime info")
        .labelNames("env", "version", "vendor", "runtime")
        .register();

String version = System.getProperty("java.runtime.version", "unknown");
String vendor = System.getProperty("java.vm.vendor", "unknown");
String runtime = System.getProperty("java.runtime.name", "unknown");

info.addLabelValues("prod", version, vendor, runtime);
info.addLabelValues("dev", version, vendor, runtime);
```

--------------------------------

### CacheMetricsCollector Usage

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/caffeine/CacheMetricsCollector.Builder.html

Example of how to initialize and register a CacheMetricsCollector to monitor a Caffeine cache.

```APIDOC
## CacheMetricsCollector Usage

### Description
To monitor a Caffeine cache, instantiate a `CacheMetricsCollector` using the builder, register it with the `PrometheusRegistry`, and add the cache instance to the collector.

### Usage Example
```java
// Note that `recordStats()` is required to gather non-zero statistics
Cache<String, String> cache = Caffeine.newBuilder().recordStats().build();
CacheMetricsCollector cacheMetrics = CacheMetricsCollector.builder().build();
PrometheusRegistry.defaultRegistry.register(cacheMetrics);
cacheMetrics.addCache("mycache", cache);
```
```

--------------------------------

### Histogram Usage

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/core/metrics/Histogram.html

Example of how to build and use a Histogram metric to record observations.

```APIDOC
## Histogram Usage

### Description
Create a new Histogram metric using the builder, register it, and record observations using label values.

### Usage Example
```java
Histogram histogram = Histogram.builder()
        .name("http_request_duration_seconds")
        .help("HTTP request service time in seconds")
        .unit(SECONDS)
        .labelNames("method", "path", "status_code")
        .register();

long start = System.nanoTime();
// do something
histogram.labelValues("GET", "/", "200").observe(Unit.nanosToSeconds(System.nanoTime() - start));
```
```

--------------------------------

### Label Name Validation

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/model/snapshots/PrometheusNaming.html

Validates label names, ensuring they do not start with reserved prefixes.

```java
public static boolean isValidLabelName(String name) {
    return isValidUtf8(name)
        && !(name.startsWith("__")
            || name.startsWith("._")
            || name.startsWith("..")
            || name.startsWith("_."));
  }
```

--------------------------------

### Load Properties from Environment

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/config/PrometheusPropertiesLoader.html

Extracts environment variables starting with IO_PROMETHEUS and normalizes them to lowercase.

```java
private static Map<Object, Object> loadPropertiesFromEnvironment() {
    Map<Object, Object> properties = new HashMap<>();
    System.getenv()
        .forEach(
            (key, value) -> {
              if (key.startsWith("IO_PROMETHEUS")) {
                String normalizedKey = key.toLowerCase(java.util.Locale.ROOT);
                properties.put(normalizedKey, value);
              }
            });
    return properties;
  }
```

--------------------------------

### Configure PushGateway Builder Instance

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/pushgateway/PushGateway.Builder.html

Methods for setting up the PushGateway builder with custom registry, escaping, and timestamp configurations.

```java
public Builder instanceIpGroupingKey() throws UnknownHostException {
  return groupingKey("instance", InetAddress.getLocalHost().getHostAddress());
}

/** Push metrics from this registry instead of {@link PrometheusRegistry#defaultRegistry}. */
public Builder registry(PrometheusRegistry registry) {
  this.registry = requireNonNull(registry, "registry must not be null");
  return this;
}

/**
 * Specify the escaping scheme to be used when pushing metrics. Default is {@link
 * EscapingScheme#UNDERSCORE_ESCAPING}.
 */
public Builder escapingScheme(EscapingScheme escapingScheme) {
  this.escapingScheme = requireNonNull(escapingScheme, "escapingScheme must not be null");
  return this;
}

/**
 * Use milliseconds for timestamps in text format? Default is {@code false}. Can be overwritten
 * at runtime with the {@code io.prometheus.exporter.timestamps_in_ms} property.
 */
public Builder prometheusTimestampsInMs(boolean prometheusTimestampsInMs) {
  this.prometheusTimestampsInMs = prometheusTimestampsInMs;
  return this;
}
```

--------------------------------

### Timer startTimer()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/datapoints/DistributionDataPoint.html

Starts a timer to measure the duration of a code block, which is then recorded as an observation.

```APIDOC
### Method
Timer startTimer()

### Description
Starts a timer. Durations are recorded in seconds. 

### Example
```java
try (Timer timer = dataPoint.startTimer()) {
    // duration of this code block will be observed.
}
```
```

--------------------------------

### Prometheus Scrape Job Configuration Snippet

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/exporter/httpserver/DefaultHandler.html

Example configuration for filtering metrics in prometheus.yaml.

```yaml
params:
    name[]:
        - my_metric_a
        - my_metric_b
```

--------------------------------

### GET /metrics

Source: https://prometheus.github.io/client_java/exporters/filter

Queries the exporter for specific metrics by providing one or more name parameters.

```APIDOC
## GET /metrics

### Description
Queries the exporter for specific metrics by providing one or more name parameters.

### Method
GET

### Endpoint
/metrics

### Parameters
#### Query Parameters
- **name[]** (string) - Optional - The name of the metric to query. Can be repeated to query multiple metrics.
```

--------------------------------

### build()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/model/snapshots/SummarySnapshot.Builder.html

Constructs and returns a new SummarySnapshot instance based on the configured builder state.

```APIDOC
### build

**Signature:** `public SummarySnapshot build()`

**Description:** Finalizes the configuration and returns a new SummarySnapshot instance.
```

--------------------------------

### Get Prometheus Metric Names

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/guava/CacheMetricsCollector.html

Returns the list of all metric names associated with the collector.

```java
@Override
  @Deprecated
  @SuppressWarnings("InlineMeSuggester")
  public List<String> getPrometheusNames() {
    return ALL_METRIC_NAMES;
  }
```

--------------------------------

### build()

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/metrics/SummaryWithCallback.Builder.html

Constructs and returns a new SummaryWithCallback instance based on the configured settings.

```APIDOC
### build()

Finalizes the configuration and returns the built SummaryWithCallback instance.

#### Returns
- **SummaryWithCallback** - The constructed metric instance.
```

--------------------------------

### Configure StateSet States and Build

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/core/metrics/StateSet.html

Defines the allowed states for the StateSet and constructs the instance. Requires non-empty state names and throws exceptions if validation fails.

```java
public Builder states(String... stateNames) {
  if (stateNames.length == 0) {
    throw new IllegalArgumentException("states cannot be empty");
  }
  this.names = Stream.of(stateNames).distinct().sorted().toArray(String[]::new);
  return this;
}

@Override
public StateSet build() {
  if (names == null) {
    throw new IllegalStateException("State names are required when building a StateSet.");
  }
  return new StateSet(this, names);
}

@Override
protected Builder self() {
  return this;
}
}
```

--------------------------------

### View Raw Metrics Output

Source: https://prometheus.github.io/client_java/getting-started/quickstart

Example of the expected output format for the custom counter metric.

```text
# HELP my_count_total example counter
# TYPE my_count_total counter
my_count_total{status="error"} 1.0
my_count_total{status="ok"} 2.0
```

--------------------------------

### Registering and Using CounterDataPoint

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/core/datapoints/CounterDataPoint.html

Demonstrates how to create a counter with labels and obtain specific CounterDataPoint instances for those labels.

```java
Counter counter = Counter.builder()
    .name("tasks_total")
    .labelNames("status")
    .register();
CounterDataPoint newTasks = counter.labelValues("new");
CounterDataPoint pendingTasks = counter.labelValues("pending");
CounterDataPoint completedTasks = counter.labelValues("completed");
```

--------------------------------

### Prometheus Scrape Configuration

Source: https://prometheus.github.io/client_java/getting-started/multi-target

Example configuration for scraping multi-target endpoints using relabeling rules.

```yaml
- job_name: "multi-target"

  # metrics_path defaults to '/metrics'
  # scheme defaults to 'http'.
  params:
    proc: [proc1, proc2]
  relabel_configs:
    - source_labels: [__address__]
      target_label: __param_target
    - source_labels: [__param_target]
      target_label: instance
    - target_label: __address__
      replacement: localhost:9401
  static_configs:
    - targets: ["target1", "target2"]
```

--------------------------------

### Configure and Build OpenMetrics 2.0 Properties

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/config/OpenMetrics2Properties.html

Use enableAll to activate all features and build to instantiate the OpenMetrics2Properties object.

```java
/** Enable all OpenMetrics 2.0 features */
    public Builder enableAll() {
      this.enabled = true;
      this.contentNegotiation = true;
      this.compositeValues = true;
      this.exemplarCompliance = true;
      this.nativeHistograms = true;
      return this;
    }

    public OpenMetrics2Properties build() {
      return new OpenMetrics2Properties(
          enabled, contentNegotiation, compositeValues, exemplarCompliance, nativeHistograms);
    }
  }
}
```

--------------------------------

### HTTPServer.Builder Configuration Methods

Source: https://prometheus.github.io/client_java/api/io/prometheus/metrics/exporter/httpserver/HTTPServer.Builder.html

Methods available on the HTTPServer.Builder to configure the server instance.

```APIDOC
## HTTPServer.Builder Methods

### port(int port)
Sets the port to bind to. Default is 0 (random port).

### hostname(String hostname)
Sets the hostname to resolve the IP address. Cannot be used with inetAddress.

### inetAddress(InetAddress address)
Sets the IP address to bind to. Cannot be used with hostname.

### executorService(ExecutorService executorService)
Sets the ExecutorService used by the server.

### registry(PrometheusRegistry registry)
Sets the PrometheusRegistry. Default is PrometheusRegistry.defaultRegistry.

### authenticator(Authenticator authenticator)
Sets the Authenticator for server authentication.

### authenticatedSubjectAttributeName(String authenticatedSubjectAttributeName)
Sets the attribute name of a Subject from a custom authenticator.

### httpsConfigurator(HttpsConfigurator configurator)
Sets the HttpsConfigurator for TLS/SSL support.

### defaultHandler(HttpHandler defaultHandler)
Overrides the default handler registered for the / endpoint.

### metricsHandlerPath(String metricsHandlerPath)
Overrides the default path for the metrics endpoint. Default is /metrics.

### registerHealthHandler(boolean registerHealthHandler)
Sets whether the health handler should be registered. Default is true.

### buildAndStart()
Builds and starts the HTTPServer instance. Returns an HTTPServer object.
```

--------------------------------

### Prometheus Metric Definitions

Source: https://prometheus.github.io/client_java/api/src-html/io/prometheus/metrics/instrumentation/jvm/JvmMemoryMetrics.Builder.html

Example output format for JVM memory pool and area metrics.

```text
jvm_memory_pool_max_bytes{pool="Code Cache"} 2.5165824E8
jvm_memory_pool_max_bytes{pool="Compressed Class Space"} 1.073741824E9
jvm_memory_pool_max_bytes{pool="Metaspace"} -1.0
jvm_memory_pool_max_bytes{pool="PS Eden Space"} 2.727870464E9
jvm_memory_pool_max_bytes{pool="PS Old Gen"} 5.542248448E9
jvm_memory_pool_max_bytes{pool="PS Survivor Space"} 2.1495808E7
# HELP jvm_memory_pool_used_bytes Used bytes of a given JVM memory pool.
# TYPE jvm_memory_pool_used_bytes gauge
jvm_memory_pool_used_bytes{pool="Code Cache"} 4065472.0
jvm_memory_pool_used_bytes{pool="Compressed Class Space"} 766680.0
jvm_memory_pool_used_bytes{pool="Metaspace"} 6659432.0
jvm_memory_pool_used_bytes{pool="PS Eden Space"} 7801536.0
jvm_memory_pool_used_bytes{pool="PS Old Gen"} 1249696.0
jvm_memory_pool_used_bytes{pool="PS Survivor Space"} 0.0
# HELP jvm_memory_used_bytes Used bytes of a given JVM memory area.
# TYPE jvm_memory_used_bytes gauge
jvm_memory_used_bytes{area="heap"} 9051232.0
jvm_memory_used_bytes{area="nonheap"} 1.1490688E7
```