Apache Tomcat

This document describes how to configure your Google Kubernetes Engine deployment so that you can use Google Cloud Managed Service for Prometheus to collect metrics from Apache Tomcat. This document shows you how to do the following:

Set up the exporter for Tomcat to report metrics.
Configure a PodMonitoring resource for Managed Service for Prometheus to collect the exported metrics.
Access a dashboard in Cloud Monitoring to view the metrics.
Configure alerting rules to monitor the metrics.

These instructions apply only if you are using managed collection with Managed Service for Prometheus. If you are using self-deployed collection, then see the source repository for the JMX exporter for installation information.

These instructions are provided as an example and are expected to work in most Kubernetes environments. If you are having trouble installing an application or exporter due to restrictive security or organizational policies, then we recommend you consult open-source documentation for support.

For information about Apache Tomcat, see Apache Tomcat .

Prerequisites

To collect metrics from Tomcat by using Managed Service for Prometheus and managed collection, your deployment must meet the following requirements:

Your cluster must be running Google Kubernetes Engine version 1.28.15-gke.2475000 or later.
You must be running Managed Service for Prometheus with managed collection enabled. For more information, see Get started with managed collection .
To use dashboards available in Cloud Monitoring for the Tomcat integration, you must use jmx-exporter version 0.17.0 or later.
For more information about available dashboards, see View dashboards .

Tomcat supports JMX, which can be enabled by configuring the CATALINA_OPTS environment variable.

Install the Tomcat exporter

We recommend that you install the Tomcat exporter, jmx-exporter , as a sidecar to your Tomcat workload. For information about using sidecars, see Extended applications on Kubernetes with multi-container pods .

To install jmx-exporter as a sidecar to Tomcat, modify your Tomcat configuration as shown in the following example:

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 : 
 //www.apache.org/licenses/LICENSE-2.0 
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 # 
  
 Unless 
  
 required 
  
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 applicable 
  
 law 
  
 or 
  
 agreed 
  
 to 
  
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 , 
  
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 governing 
  
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 the 
  
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 . 
 apiVersion 
 : 
  
 v1 
 kind 
 : 
  
 ConfigMap 
 metadata 
 : 
  
 name 
 : 
  
 tomcat 
 - 
 exporter 
 data 
 : 
  
 config 
 . 
 yml 
 : 
  
 | 
  
 hostPort 
 : 
  
 127.0.0.1 
 : 
 9010 
  
 lowercaseOutputLabelNames 
 : 
  
 true 
  
 lowercaseOutputName 
 : 
  
 true 
  
 rules 
 : 
  
 - 
  
 pattern 
 : 
  
 ' 
 Catalina<type 
 = 
 GlobalRequestProcessor 
 , 
  
 name 
 = 
 \ 
 "(\w+-\w+)-(\d+)\"><>(\w+):' 
 name: tomcat_$3_total 
 labels: 
 port: " 
 $ 
 2 
 " 
 protocol: " 
 $ 
 1 
 " 
 help: Tomcat global $3 
 type: COUNTER 
 - pattern: 'Catalina<j2eeType=Servlet, WebModule=//([-a-zA-Z0-9+&@#/%?=~_|!:.,;]*[-a-zA-Z0-9+&@#/%=~_|]), name=([-a-zA-Z0-9+/$%~_-|!.]*), J2EEApplication=none, J2EEServer=none><>(requestCount|maxTime|processingTime|errorCount):' 
 name: tomcat_servlet_$3_total 
 labels: 
 module: " 
 $ 
 1 
 " 
 servlet: " 
 $ 
 2 
 " 
 help: Tomcat servlet $3 total 
 type: COUNTER 
 - pattern: 'Catalina<type=ThreadPool, name=" 
 ( 
 \ 
 w 
 +- 
 \ 
 w 
 + 
 ) 
 - 
 ( 
 \ 
 d 
 + 
 ) 
 "><>(currentThreadCount|currentThreadsBusy|keepAliveCount|pollerThreadCount|connectionCount):' 
 name: tomcat_threadpool_$3 
 labels: 
 port: " 
 $ 
 2 
 " 
 protocol: " 
 $ 
 1 
 " 
 help: Tomcat threadpool $3 
 type: GAUGE 
 - pattern: 'Catalina<type=Manager, host=([-a-zA-Z0-9+&@#/%?=~_|!:.,;]*[-a-zA-Z0-9+&@#/%=~_|]), context=([-a-zA-Z0-9+/$%~_-|!.]*)><>(processingTime|sessionCounter|rejectedSessions|expiredSessions):' 
 name: tomcat_session_$3_total 
 labels: 
 context: " 
 $ 
 2 
 " 
 host: " 
 $ 
 1 
 " 
 help: Tomcat session $3 total 
 type: COUNTER 
 --- 
 apiVersion: apps/v1 
 kind: Deployment 
 metadata: 
 name: tomcat 
 spec: 
 selector: 
 matchLabels: 
 +     app.kubernetes.io/name: tomcat 
 template: 
 metadata: 
 labels: 
 +       app.kubernetes.io/name: tomcat 
 spec: 
 containers: 
 - name: tomcat 
 image: tomcat:9.0.46-jdk11-openjdk-buster 
 ports: 
 - containerPort: 8080 
 name: http 
 env: 
 +           - name: CATALINA_OPTS 
 +             value: " 
 - 
 Dcom 
 . 
 sun 
 . 
 management 
 . 
 jmxremote 
 . 
 local 
 . 
 only 
 = 
 false 
  
 - 
 Dcom 
 . 
 sun 
 . 
 management 
 . 
 jmxremote 
 . 
 authenticate 
 = 
 false 
  
 - 
 Dcom 
 . 
 sun 
 . 
 management 
 . 
 jmxremote 
 . 
 ssl 
 = 
 false 
  
 - 
 Dcom 
 . 
 sun 
 . 
 management 
 . 
 jmxremote 
 . 
 port 
 = 
 9010 
  
 - 
 Dcom 
 . 
 sun 
 . 
 management 
 . 
 jmxremote 
 . 
 rmi 
 . 
 port 
 = 
 9010 
 " 
 +       - name: exporter 
 +         image: bitnami/jmx-exporter:0.17.0 
 +         ports: 
 +           - containerPort: 9113 
 +             name: prometheus 
 +         command: 
 +           - java 
 +           - -jar 
 +           - jmx_prometheus_httpserver.jar 
 +         args: 
 +           - " 
 9113 
 " 
 + 
  
 - 
  
 / 
 opt 
 / 
 jmx_exporter 
 / 
 config 
 . 
 yml 
 + 
  
 volumeMounts 
 : 
 + 
  
 - 
  
 mountPath 
 : 
  
 / 
 opt 
 / 
 jmx_exporter 
 / 
 config 
 . 
 yml 
 + 
  
 subPath 
 : 
  
 config 
 . 
 yml 
 + 
  
 name 
 : 
  
 tomcat 
 - 
 exporter 
 + 
  
 volumes 
 : 
 + 
  
 - 
  
 name 
 : 
  
 tomcat 
 - 
 exporter 
 + 
  
 configMap 
 : 
 + 
  
 name 
 : 
  
 tomcat 
 - 
 exporter 
 + 
  
 items 
 : 
 + 
  
 - 
  
 key 
 : 
  
 config 
 . 
 yml 
 + 
  
 path 
 : 
  
 config 
 . 
 yml

You must add any lines preceded by the + symbol to your configuration.

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

Define a PodMonitoring resource

For target discovery, the Managed Service for Prometheus Operator requires a PodMonitoring resource that corresponds to the JMX exporter in the same namespace.

You can use the following PodMonitoring configuration:

  # Copyright 2023 Google LLC 
 # 
 # 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 
 # 
 #     https://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. 
 apiVersion 
 : 
  
 monitoring.googleapis.com/v1 
 kind 
 : 
  
 PodMonitoring 
 metadata 
 : 
  
 name 
 : 
  
 tomcat 
  
 labels 
 : 
  
 app.kubernetes.io/name 
 : 
  
 tomcat 
  
 app.kubernetes.io/part-of 
 : 
  
 google-cloud-managed-prometheus 
 spec 
 : 
  
 endpoints 
 : 
  
 - 
  
 port 
 : 
  
 prometheus 
  
 scheme 
 : 
  
 http 
  
 interval 
 : 
  
 30s 
  
 path 
 : 
  
 /metrics 
  
 selector 
 : 
  
 matchLabels 
 : 
  
 app.kubernetes.io/name 
 : 
  
 tomcat

Ensure that the label selectors and the port match the selectors and port used in Install the Tomcat exporter .

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

Define rules and alerts

You can use the following Rules configuration to define alerts on your Tomcat metrics:

  # Copyright 2023 Google LLC 
 # 
 # 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 
 # 
 #     https://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. 
 apiVersion 
 : 
  
 monitoring.googleapis.com/v1 
 kind 
 : 
  
 Rules 
 metadata 
 : 
  
 name 
 : 
  
 tomcat-rules 
  
 labels 
 : 
  
 app.kubernetes.io/component 
 : 
  
 rules 
  
 app.kubernetes.io/name 
 : 
  
 tomcat-rules 
  
 app.kubernetes.io/part-of 
 : 
  
 google-cloud-managed-prometheus 
 spec 
 : 
  
 groups 
 : 
  
 - 
  
 name 
 : 
  
 tomcat 
  
 interval 
 : 
  
 30s 
  
 rules 
 : 
  
 - 
  
 alert 
 : 
  
 TomcatHighRequestRate 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Tomcat high request rate 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Tomcat high request rate (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 rate(tomcat_requestcount_total[5m]) >= 100 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 warning 
  
 - 
  
 alert 
 : 
  
 TomcatLowRequestRate 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Tomcat low request rate 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Tomcat low request rate (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 rate(tomcat_requestcount_total[5m]) <= 10 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 warning 
  
 - 
  
 alert 
 : 
  
 TomcatHighErrorRate 
  
 annotations 
 : 
  
 description 
 : 
  
 |- 
  
 Tomcat high error rate 
  
 VALUE = {{ $value }} 
  
 LABELS: {{ $labels }} 
  
 summary 
 : 
  
 Tomcat high error rate (instance {{ $labels.instance }}) 
  
 expr 
 : 
  
 rate(tomcat_errorcount_total[5m]) > 100 
  
 for 
 : 
  
 5m 
  
 labels 
 : 
  
 severity 
 : 
  
 warning

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME 
-f FILE_NAME

You can also use Terraform to manage your configurations.

For more information about applying rules to your cluster, see Managed rule evaluation and alerting .

You can adjust the alert thresholds to suit your application.

Verify the configuration

You can use Metrics Explorer to verify that you correctly configured the JMX exporter. It might take one or two minutes for Cloud Monitoring to ingest your metrics.

To verify the metrics are ingested, do the following:

In the Google Cloud console, go to the Metrics explorer page:

Go to Metrics explorer

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
In the toolbar of the query-builder pane, select the button whose name is either MQL or PromQL .
Verify that PromQL is selected in the Language toggle. The language toggle is in the same toolbar that lets you format your query.

Enter and run the following query:

up{job="tomcat", cluster=" CLUSTER_NAME 
", namespace=" NAMESPACE_NAME 
"}

View dashboards

The Cloud Monitoring integration includes the Tomcat Prometheus Overview dashboard. Dashboards are automatically installed when you configure the integration. You can also view static previews of dashboards without installing the integration.

To view an installed dashboard, do the following:

In the Google Cloud console, go to the Dashboards page:

Go to Dashboards

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
Select the Dashboard List tab.
Choose the Integrations category.
Click the name of the dashboard, for example, Tomcat Prometheus Overview .

To view a static preview of the dashboard, do the following:

In the Google Cloud console, go to the Integrations page:

Go to Integrations

If you use the search bar to find this page, then select the result whose subheading is Monitoring .
Click the Kubernetes Engine deployment-platform filter.
Locate the Apache Tomcat integration and click View Details .
Select the Dashboards tab.

Troubleshooting

For information about troubleshooting metric ingestion problems, see Problems with collection from exporters in Troubleshooting ingestion-side problems .

Apache Tomcat Stay organized with collections Save and categorize content based on your preferences.

Prerequisites

Install the Tomcat exporter

Define a PodMonitoring resource

Define rules and alerts

Verify the configuration

View dashboards

Troubleshooting

Apache Tomcat