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Make /metrics the only Prometheus metrics endpoint #6476

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merged 3 commits into from
May 29, 2024
Merged

Make /metrics the only Prometheus metrics endpoint #6476

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34b3d38
Make /metrics the only Prometheus metrics endpoint
fstab May 26, 2024
c7e1219
Add PrometheusHttpServerBuilder#setDefaultHandler
jack-berg May 29, 2024
a2f71a6
Merge branch 'main' of https://github.com/open-telemetry/opentelemetr…
jack-berg May 29, 2024
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7 changes: 4 additions & 3 deletions ...s/prometheus/src/main/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@

package io.opentelemetry.exporter.prometheus;

import com.sun.net.httpserver.HttpHandler;
import io.opentelemetry.sdk.common.CompletableResultCode;
import io.opentelemetry.sdk.common.export.MemoryMode;
import io.opentelemetry.sdk.internal.DaemonThreadFactory;
Expand All @@ -18,7 +19,6 @@
import io.opentelemetry.sdk.metrics.export.CollectionRegistration;
import io.opentelemetry.sdk.metrics.export.MetricReader;
import io.prometheus.metrics.exporter.httpserver.HTTPServer;
import io.prometheus.metrics.exporter.httpserver.MetricsHandler;
import io.prometheus.metrics.model.registry.PrometheusRegistry;
import java.io.IOException;
import java.io.UncheckedIOException;
Expand Down Expand Up @@ -64,7 +64,8 @@ public static PrometheusHttpServerBuilder builder() {
PrometheusRegistry prometheusRegistry,
boolean otelScopeEnabled,
@Nullable Predicate<String> allowedResourceAttributesFilter,
MemoryMode memoryMode) {
MemoryMode memoryMode,
@Nullable HttpHandler defaultHandler) {
this.builder = builder;
this.prometheusMetricReader =
new PrometheusMetricReader(otelScopeEnabled, allowedResourceAttributesFilter);
Expand All @@ -86,7 +87,7 @@ public static PrometheusHttpServerBuilder builder() {
.port(port)
.executorService(executor)
.registry(prometheusRegistry)
.defaultHandler(new MetricsHandler(prometheusRegistry))
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Let's add a configuration option for this to PrometheusHttpServerBuilder:

public PrometheuesHttpServerBuilder setDefaultHandler(com.sun.net.httpserver.HttpHandler defaultHandler)

This will allow users to depend on this behavior to restore the current behavior (although it requires programmatic configuration) while aligning with standard prometheus client library behavior.

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I pushed a commit to add this but it broke the animalsniffer check because com.sun.net.httpserver.HttpHandler isn't available in the android API. Prometheus exporter doesn't need to support android environments, and doesn't work on them currently despite animalsniffer passing (animalsniffer apparently can't detect usage of unsupported APIs in dependencies).

I opened #6478 to separately address this. Can merge that, then merge main into this branch and merge this PR.

.defaultHandler(defaultHandler)
.buildAndStart();
} catch (IOException e) {
throw new UncheckedIOException("Could not create Prometheus HTTP server", e);
Expand Down
22 changes: 21 additions & 1 deletion ...theus/src/main/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerBuilder.java
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Expand Up @@ -8,6 +8,7 @@
import static io.opentelemetry.api.internal.Utils.checkArgument;
import static java.util.Objects.requireNonNull;

import com.sun.net.httpserver.HttpHandler;
import io.opentelemetry.sdk.common.export.MemoryMode;
import io.prometheus.metrics.model.registry.PrometheusRegistry;
import java.util.concurrent.ExecutorService;
Expand All @@ -29,6 +30,7 @@ public final class PrometheusHttpServerBuilder {
@Nullable private Predicate<String> allowedResourceAttributesFilter;
@Nullable private ExecutorService executor;
private MemoryMode memoryMode = DEFAULT_MEMORY_MODE;
@Nullable private HttpHandler defaultHandler;

PrometheusHttpServerBuilder() {}

Expand Down Expand Up @@ -107,6 +109,23 @@ public PrometheusHttpServerBuilder setMemoryMode(MemoryMode memoryMode) {
return this;
}

/**
* Override the default handler for serving the "/", "/**" endpoint.
*
* <p>This can be used to serve metrics on additional paths besides the default "/metrics". For
* example: <code>
* PrometheusHttpServer.builder()
* .setPrometheusRegistry(prometheusRegistry)
* .setDefaultHandler(new MetricsHandler(prometheusRegistry))
* .build()
* </code>
*/
public PrometheusHttpServerBuilder setDefaultHandler(HttpHandler defaultHandler) {
requireNonNull(defaultHandler, "defaultHandler");
this.defaultHandler = defaultHandler;
return this;
}

/**
* Returns a new {@link PrometheusHttpServer} with the configuration of this builder which can be
* registered with a {@link io.opentelemetry.sdk.metrics.SdkMeterProvider}.
Expand All @@ -120,6 +139,7 @@ public PrometheusHttpServer build() {
prometheusRegistry,
otelScopeEnabled,
allowedResourceAttributesFilter,
memoryMode);
memoryMode,
defaultHandler);
}
}
46 changes: 44 additions & 2 deletions ...ometheus/src/test/java/io/opentelemetry/exporter/prometheus/PrometheusHttpServerTest.java
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Expand Up @@ -35,6 +35,7 @@
import io.opentelemetry.sdk.metrics.internal.data.ImmutableSumData;
import io.opentelemetry.sdk.resources.Resource;
import io.prometheus.metrics.exporter.httpserver.HTTPServer;
import io.prometheus.metrics.exporter.httpserver.MetricsHandler;
import io.prometheus.metrics.model.registry.PrometheusRegistry;
import java.io.ByteArrayInputStream;
import java.io.IOException;
Expand Down Expand Up @@ -229,7 +230,7 @@ void fetchOpenMetrics() {
void fetchFiltered() {
AggregatedHttpResponse response =
client
.get("/?name[]=grpc_name_unit_total&name[]=bears_total&name[]=target_info")
.get("/metrics?name[]=grpc_name_unit_total&name[]=bears_total&name[]=target_info")
.aggregate()
.join();
assertThat(response.status()).isEqualTo(HttpStatus.OK);
Expand All @@ -245,6 +246,47 @@ void fetchFiltered() {
+ "target_info{kr=\"vr\"} 1\n");
}

@Test
void fetchOverrideDefaultHandler() {
PrometheusRegistry registry = new PrometheusRegistry();
try (PrometheusHttpServer prometheusServer =
PrometheusHttpServer.builder()
.setHost("localhost")
.setPort(0)
.setPrometheusRegistry(registry)
// Set the default handler to serve metrics on /**
.setDefaultHandler(new MetricsHandler(registry))
.build()) {
prometheusServer.register(
new CollectionRegistration() {
@Override
public Collection<MetricData> collectAllMetrics() {
return metricData.get();
}
});
WebClient client =
WebClient.builder("http://localhost:" + prometheusServer.getAddress().getPort())
.decorator(RetryingClient.newDecorator(RetryRule.failsafe()))
.build();

// Fetch metrics from / instead of /metrics
AggregatedHttpResponse response = client.get("/").aggregate().join();
assertThat(response.status()).isEqualTo(HttpStatus.OK);
assertThat(response.headers().get(HttpHeaderNames.CONTENT_TYPE))
.isEqualTo("text/plain; version=0.0.4; charset=utf-8");
assertThat(response.contentUtf8())
.isEqualTo(
"# HELP grpc_name_unit_total long_description\n"
+ "# TYPE grpc_name_unit_total counter\n"
+ "grpc_name_unit_total{kp=\"vp\",otel_scope_name=\"grpc\",otel_scope_version=\"version\"} 5.0\n"
+ "# HELP http_name_unit_total double_description\n"
+ "# TYPE http_name_unit_total counter\n"
+ "http_name_unit_total{kp=\"vp\",otel_scope_name=\"http\",otel_scope_version=\"version\"} 3.5\n"
+ "# TYPE target_info gauge\n"
+ "target_info{kr=\"vr\"} 1\n");
}
}

@SuppressWarnings("resource")
@Test
void fetchPrometheusCompressed() throws IOException {
Expand Down Expand Up @@ -275,7 +317,7 @@ void fetchPrometheusCompressed() throws IOException {
@SuppressWarnings("resource")
@Test
void fetchHead() {
AggregatedHttpResponse response = client.head("/").aggregate().join();
AggregatedHttpResponse response = client.head("/metrics").aggregate().join();
assertThat(response.status()).isEqualTo(HttpStatus.OK);
assertThat(response.headers().get(HttpHeaderNames.CONTENT_TYPE))
.isEqualTo("text/plain; version=0.0.4; charset=utf-8");
Expand Down
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