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Add a monitor for the OpenMetrics endpoint
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This populates the running and queued query metrics for active load balancing, and
allows defining health using minimum and maximum values for arbitrary metrics

Co-authored-by: Yuya Ebihara <[email protected]>
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willmostly and ebyhr committed Jan 30, 2025
1 parent 379ca35 commit f0ae06b
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32 changes: 32 additions & 0 deletions docs/installation.md
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Expand Up @@ -387,6 +387,38 @@ monitor:

All timeout parameters are optional.

#### METRICS

This pulls statistics from Trino's [OpenMetrics](https://openmetrics.io/) endpoint.
It retrieves the number of running and queued queries for use with
the `QueryCountBasedRouter` (either `METRICS` or `JDBC` must be enabled if
`QueryCountBasedRouter` is used).

This monitor allows customizing health definitions by comparing metrics to fixed
values. This is configured through two maps: `metricMinimumValues` and
`metricMaximumValues`. The keys of these maps are the metric names, and the values
are the minimum or maximum values (inclusive) that are considered healthy. By default,
the only metric populated is:

```yaml
monitorConfiguration:
metricMinimumValues:
trino_metadata_name_DiscoveryNodeManager_ActiveNodeCount: 1
```

This requires the cluster to have at least one active worker node in order to be considered
healthy. The map is overwritten if configured explicitly. For example, to increase the minimum
worker count to 10 and disqualify clusters that have been experiencing frequent major Garbage
Collections, set

```yaml
monitorConfiguration:
metricMinimumValues:
trino_metadata_name_DiscoveryNodeManager_ActiveNodeCount: 10
metricMaximumValues:
io_airlift_stats_name_GcMonitor_MajorGc_FiveMinutes_count: 2
```

#### JDBC

This uses a JDBC connection to query `system.runtime` tables for cluster
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1 change: 1 addition & 0 deletions gateway-ha/pom.xml
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Expand Up @@ -492,6 +492,7 @@
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<argLine>-Djol.skipHotspotSAAttach=true</argLine>
<!-- This is needed because we call main() in test setups. Otherwise Guice singleton won't work. -->
<reuseForks>false</reuseForks>
</configuration>
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Expand Up @@ -27,9 +27,7 @@
import static io.airlift.http.client.JsonResponseHandler.createJsonResponseHandler;
import static io.airlift.http.client.Request.Builder.prepareGet;
import static io.airlift.json.JsonCodec.jsonCodec;
import static java.net.HttpURLConnection.HTTP_BAD_GATEWAY;
import static java.net.HttpURLConnection.HTTP_GATEWAY_TIMEOUT;
import static java.net.HttpURLConnection.HTTP_UNAVAILABLE;
import static io.trino.gateway.ha.clustermonitor.MonitorUtils.shouldRetry;
import static java.util.Objects.requireNonNull;

public class ClusterStatsInfoApiMonitor
Expand Down Expand Up @@ -88,16 +86,4 @@ private TrinoStatus checkStatus(String baseUrl, int retriesRemaining)
}
return TrinoStatus.UNHEALTHY;
}

public static boolean shouldRetry(int statusCode)
{
switch (statusCode) {
case HTTP_BAD_GATEWAY:
case HTTP_UNAVAILABLE:
case HTTP_GATEWAY_TIMEOUT:
return true;
default:
return false;
}
}
}
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@@ -0,0 +1,200 @@
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.trino.gateway.ha.clustermonitor;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import io.airlift.http.client.HttpClient;
import io.airlift.http.client.HttpUriBuilder;
import io.airlift.http.client.Request;
import io.airlift.http.client.Response;
import io.airlift.http.client.ResponseHandler;
import io.airlift.http.client.UnexpectedResponseException;
import io.airlift.log.Logger;
import io.trino.gateway.ha.config.BackendStateConfiguration;
import io.trino.gateway.ha.config.MonitorConfiguration;
import io.trino.gateway.ha.config.ProxyBackendConfiguration;
import io.trino.gateway.ha.security.util.BasicCredentials;

import java.io.IOException;
import java.net.URI;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;

import static com.google.common.base.Strings.isNullOrEmpty;
import static com.google.common.collect.ImmutableMap.toImmutableMap;
import static io.airlift.http.client.HttpUriBuilder.uriBuilderFrom;
import static io.airlift.http.client.Request.Builder.prepareGet;
import static io.airlift.http.client.ResponseHandlerUtils.propagate;
import static io.trino.gateway.ha.clustermonitor.MonitorUtils.shouldRetry;
import static java.lang.String.format;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Objects.requireNonNull;

public class ClusterStatsMetricsMonitor
implements ClusterStatsMonitor
{
public static final String RUNNING_QUERIES_METRIC = "trino_execution_name_QueryManager_RunningQueries";
public static final String QUEUED_QUERIES_METRIC = "trino_execution_name_QueryManager_QueuedQueries";
private static final Logger log = Logger.get(ClusterStatsMetricsMonitor.class);

private final HttpClient httpClient;
private final int retries;
private final MetricsResponseHandler metricsResponseHandler;
private final Header identityHeader;
private final String metricsEndpoint;
private final ImmutableSet<String> metricNames;
private final Map<String, Float> metricMinimumValues;
private final Map<String, Float> metricMaximumValues;

public ClusterStatsMetricsMonitor(HttpClient httpClient, BackendStateConfiguration backendStateConfiguration, MonitorConfiguration monitorConfiguration)
{
this.httpClient = requireNonNull(httpClient, "httpClient is null");
retries = monitorConfiguration.getRetries();
if (!isNullOrEmpty(backendStateConfiguration.getPassword())) {
identityHeader = new Header("Authorization",
new BasicCredentials(backendStateConfiguration.getUsername(), backendStateConfiguration.getPassword()).getBasicAuthHeader());
}
else {
identityHeader = new Header("X-Trino-User", backendStateConfiguration.getUsername());
}
metricsEndpoint = monitorConfiguration.getMetricsEndpoint();
metricMinimumValues = ImmutableMap.copyOf(monitorConfiguration.getMetricMinimumValues());
metricMaximumValues = ImmutableMap.copyOf(monitorConfiguration.getMetricMaximumValues());
metricNames = ImmutableSet.<String>builder()
.add(RUNNING_QUERIES_METRIC, QUEUED_QUERIES_METRIC)
.addAll(metricMinimumValues.keySet())
.addAll(metricMaximumValues.keySet())
.build();
metricsResponseHandler = new MetricsResponseHandler(metricNames);
}

private static ClusterStats getUnhealthyStats(ProxyBackendConfiguration backend)
{
return ClusterStats.builder(backend.getName())
.trinoStatus(TrinoStatus.UNHEALTHY)
.proxyTo(backend.getProxyTo())
.externalUrl(backend.getExternalUrl())
.routingGroup(backend.getRoutingGroup())
.build();
}

@Override
public ClusterStats monitor(ProxyBackendConfiguration backend)
{
Map<String, String> metrics = getMetrics(backend.getProxyTo(), retries);
if (metrics.isEmpty()) {
log.error("No metrics available for %s!", backend.getName());
return getUnhealthyStats(backend);
}

for (Map.Entry<String, Float> entry : metricMinimumValues.entrySet()) {
if (!metrics.containsKey(entry.getKey())
|| Float.parseFloat(metrics.get(entry.getKey())) < entry.getValue()) {
log.warn("Health metric value below min for cluster %s: %s=%s", backend.getName(), entry.getKey(), metrics.get(entry.getKey()));
return getUnhealthyStats(backend);
}
}

for (Map.Entry<String, Float> entry : metricMaximumValues.entrySet()) {
if (!metrics.containsKey(entry.getKey())
|| Float.parseFloat(metrics.get(entry.getKey())) > entry.getValue()) {
log.warn("Health metric value over max for cluster %s: %s=%s", backend.getName(), entry.getKey(), metrics.get(entry.getKey()));
return getUnhealthyStats(backend);
}
}
return ClusterStats.builder(backend.getName())
.trinoStatus(TrinoStatus.HEALTHY)
.runningQueryCount((int) Float.parseFloat(metrics.get(RUNNING_QUERIES_METRIC)))
.queuedQueryCount((int) Float.parseFloat(metrics.get(QUEUED_QUERIES_METRIC)))
.proxyTo(backend.getProxyTo())
.externalUrl(backend.getExternalUrl())
.routingGroup(backend.getRoutingGroup())
.build();
}

private Map<String, String> getMetrics(String baseUrl, int retriesRemaining)
{
HttpUriBuilder uri = uriBuilderFrom(URI.create(baseUrl)).appendPath(metricsEndpoint);
for (String metric : metricNames) {
uri.addParameter("name[]", metric);
}

Request request = prepareGet()
.setUri(uri.build())
.addHeader(identityHeader.name, identityHeader.value)
.addHeader("Content-Type", "application/openmetrics-text; version=1.0.0; charset=utf-8")
.build();
try {
return httpClient.execute(request, metricsResponseHandler);
}
catch (UnexpectedResponseException e) {
if (shouldRetry(e.getStatusCode())) {
if (retriesRemaining > 0) {
log.warn("Retrying health check on error: %s, ", e.toString());
return getMetrics(baseUrl, retriesRemaining - 1);
}
log.error("Encountered error %s, no retries remaining", e.toString());
}
log.error(e, "Health check failed with non-retryable response.\n%s", e.toString());
}
catch (Exception e) {
log.error(e, "Exception checking %s for health", request.getUri());
}
return ImmutableMap.of();
}

private static class MetricsResponseHandler
implements ResponseHandler<Map<String, String>, RuntimeException>
{
private final ImmutableSet<String> requiredKeys;

public MetricsResponseHandler(Set<String> requiredKeys)
{
this.requiredKeys = ImmutableSet.copyOf(requiredKeys);
}

@Override
public Map<String, String> handleException(Request request, Exception exception)
throws RuntimeException
{
throw propagate(request, exception);
}

@Override
public Map<String, String> handle(Request request, Response response)
throws RuntimeException
{
try {
String responseBody = new String(response.getInputStream().readAllBytes(), UTF_8);
Map<String, String> metrics = Arrays.stream(responseBody.split("\n"))
.filter(line -> !line.startsWith("#"))
.collect(toImmutableMap(s -> s.split(" ")[0], s -> s.split(" ")[1]));
if (!metrics.keySet().containsAll(requiredKeys)) {
throw new UnexpectedResponseException(
format("Request is missing required keys: \n%s\nin response: '%s'", String.join("\n", requiredKeys), responseBody),
request,
response);
}
return metrics;
}
catch (IOException e) {
throw new UnexpectedResponseException(request, response);
}
}
}

private record Header(String name, String value) {}
}
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/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.trino.gateway.ha.clustermonitor;

import static java.net.HttpURLConnection.HTTP_BAD_GATEWAY;
import static java.net.HttpURLConnection.HTTP_GATEWAY_TIMEOUT;
import static java.net.HttpURLConnection.HTTP_UNAVAILABLE;

public final class MonitorUtils
{
private MonitorUtils() {}

public static boolean shouldRetry(int statusCode)
{
return switch (statusCode) {
case HTTP_BAD_GATEWAY, HTTP_UNAVAILABLE, HTTP_GATEWAY_TIMEOUT -> true;
default -> false;
};
}
}
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Expand Up @@ -18,5 +18,6 @@ public enum ClusterStatsMonitorType
NOOP,
INFO_API,
UI_API,
JDBC
JDBC,
METRICS
}
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Expand Up @@ -13,9 +13,12 @@
*/
package io.trino.gateway.ha.config;

import com.google.common.collect.ImmutableMap;
import io.airlift.units.Duration;
import io.trino.gateway.ha.clustermonitor.ActiveClusterMonitor;

import java.util.Map;

import static java.util.concurrent.TimeUnit.SECONDS;

public class MonitorConfiguration
Expand All @@ -28,6 +31,13 @@ public class MonitorConfiguration

private boolean explicitPrepare;

private String metricsEndpoint = "/metrics";

// Require 1 node for health by default. This configuration only applies to the ClusterStatsMetricsMonitor
private Map<String, Float> metricMinimumValues = ImmutableMap.of("trino_metadata_name_DiscoveryNodeManager_ActiveNodeCount", 1f);

private Map<String, Float> metricMaximumValues = ImmutableMap.of();

public MonitorConfiguration() {}

public int getTaskDelaySeconds()
Expand Down Expand Up @@ -69,4 +79,34 @@ public void setExplicitPrepare(boolean explicitPrepare)
{
this.explicitPrepare = explicitPrepare;
}

public String getMetricsEndpoint()
{
return metricsEndpoint;
}

public void setMetricsEndpoint(String metricsEndpoint)
{
this.metricsEndpoint = metricsEndpoint;
}

public Map<String, Float> getMetricMinimumValues()
{
return metricMinimumValues;
}

public void setMetricMinimumValues(Map<String, Float> metricMinimumValues)
{
this.metricMinimumValues = ImmutableMap.copyOf(metricMinimumValues);
}

public Map<String, Float> getMetricMaximumValues()
{
return ImmutableMap.copyOf(metricMaximumValues);
}

public void setMetricMaximumValues(Map<String, Float> metricMaximumValues)
{
this.metricMaximumValues = metricMaximumValues;
}
}
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Expand Up @@ -22,6 +22,7 @@
import io.trino.gateway.ha.clustermonitor.ClusterStatsHttpMonitor;
import io.trino.gateway.ha.clustermonitor.ClusterStatsInfoApiMonitor;
import io.trino.gateway.ha.clustermonitor.ClusterStatsJdbcMonitor;
import io.trino.gateway.ha.clustermonitor.ClusterStatsMetricsMonitor;
import io.trino.gateway.ha.clustermonitor.ClusterStatsMonitor;
import io.trino.gateway.ha.clustermonitor.ClusterStatsObserver;
import io.trino.gateway.ha.clustermonitor.ForMonitor;
Expand Down Expand Up @@ -228,6 +229,7 @@ public ClusterStatsMonitor getClusterStatsMonitor(@ForMonitor HttpClient httpCli
case INFO_API -> new ClusterStatsInfoApiMonitor(httpClient, configuration.getMonitor());
case UI_API -> new ClusterStatsHttpMonitor(configuration.getBackendState());
case JDBC -> new ClusterStatsJdbcMonitor(configuration.getBackendState(), configuration.getMonitor());
case METRICS -> new ClusterStatsMetricsMonitor(httpClient, configuration.getBackendState(), configuration.getMonitor());
case NOOP -> new NoopClusterStatsMonitor();
};
}
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