Apache Tomcat

The Apache Tomcat integration collects traffic-related metrics, such as the number of active sessions or network throughput. The integration also collects access and Catalina logs. Access logs are parsed into a JSON payload focused on request details, whereas Catalina logs are parsed for general details. The tomcat receiver collects telemetry from the Tomcat server's Java Virtual Machine (JVM) via JMX.

For more information about Tomcat, see the Apache Tomcat documentation.

Prerequisites

To collect Tomcat telemetry, you must install the Ops Agent:

For metrics, install version 2.9.0 or higher.
For logs, install version 2.9.0 or higher.

This integration supports Tomcat versions 10.x and 9.0.x.

Configure your Tomcat instance

To expose a JMX endpoint, you must set the com.sun.management.jmxremote.port system property when starting the JVM. We also recommend setting the com.sun.management.jmxremote.rmi.port system property to the same port. To expose a JMX endpoint remotely, you must also set the java.rmi.server.hostname system property.

By default, these properties are set in a Tomcat deployment's tomcat-env.sh file.

To set system properties by using command-line arguments, prepend the property name with -D when starting the JVM. For example, to set com.sun.management.jmxremote.port to port 8050, specify the following when starting the JVM:

-Dcom.sun.management.jmxremote.port=8050

Configure the Ops Agent for Tomcat

Following the guide to Configure the Ops Agent, add the required elements to collect telemetry from Tomcat instances, and restart the agent.

Example configuration

The following commands create the configuration to collect and ingest telemetry for Tomcat:

# Configures Ops Agent to collect telemetry from the app. You must restart the agent for the configuration to take effect.

set -e

# Check if the file exists
if [ ! -f /etc/google-cloud-ops-agent/config.yaml ]; then
  # Create the file if it doesn't exist.
  sudo mkdir -p /etc/google-cloud-ops-agent
  sudo touch /etc/google-cloud-ops-agent/config.yaml
fi

# Create a back up of the existing file so existing configurations are not lost.
sudo cp /etc/google-cloud-ops-agent/config.yaml /etc/google-cloud-ops-agent/config.yaml.bak

# Configure the Ops Agent.
sudo tee /etc/google-cloud-ops-agent/config.yaml > /dev/null << EOF
metrics:
  receivers:
    tomcat:
      type: tomcat
      endpoint: service:jmx:rmi:///jndi/rmi://127.0.0.1:8050/jmxrmi
  service:
    pipelines:
      tomcat:
        receivers:
          - tomcat

logging:
  receivers:
    tomcat_access:
      type: tomcat_access
    tomcat_system:
      type: tomcat_system
  service:
    pipelines:
      tomcat:
        receivers:
          - tomcat_access
          - tomcat_system
EOF

For these changes to take effect, you must restart the Ops Agent:

Linux

To restart the agent, run the following command on your instance:
```
sudo systemctl restart google-cloud-ops-agent
```
To confirm that the agent restarted, run the following command and verify that the components "Metrics Agent" and "Logging Agent" started:
```
sudo systemctl status "google-cloud-ops-agent*"
```

Windows

Connect to your instance using RDP or a similar tool and login to Windows.
Open a PowerShell terminal with administrator privileges by right-clicking the PowerShell icon and selecting Run as Administrator
To restart the agent, run the following PowerShell command:
```
Restart-Service google-cloud-ops-agent -Force
```
To confirm that the agent restarted, run the following command and verify that the components "Metrics Agent" and "Logging Agent" started:
```
Get-Service google-cloud-ops-agent*
```

Configure logs collection

To ingest logs from Tomcat, you must create a receiver for the logs that Tomcat produces and then create a pipeline for the new receiver.

To configure a receiver for your tomcat_system logs, specify the following fields:

Field	Default	Description
`exclude_paths`		A list of filesystem path patterns to exclude from the set matched by `include_paths`.
`include_paths`	`[/opt/tomcat/logs/catalina.out]`	A list of filesystem paths to read by tailing each file. A wild card (`*`) can be used in the paths.
`record_log_file_path`	`false`	If set to `true`, then the path to the specific file from which the log record was obtained appears in the output log entry as the value of the `agent.googleapis.com/log_file_path` label. When using a wildcard, only the path of the file from which the record was obtained is recorded.
`type`		The value must be `tomcat_system`.
`wildcard_refresh_interval`	`60s`	The interval at which wildcard file paths in `include_paths` are refreshed. Given as a time duration, for example `30s` or `2m`. This property might be useful under high logging throughputs where log files are rotated faster than the default interval.

To configure a receiver for your tomcat_access logs, specify the following fields:

Field	Default	Description
`exclude_paths`		A list of filesystem path patterns to exclude from the set matched by `include_paths`.
`include_paths`	`[/opt/tomcat/logs/localhost_access_log*.txt]`	A list of filesystem paths to read by tailing each file. A wild card (`*`) can be used in the paths.
`record_log_file_path`	`false`	If set to `true`, then the path to the specific file from which the log record was obtained appears in the output log entry as the value of the `agent.googleapis.com/log_file_path` label. When using a wildcard, only the path of the file from which the record was obtained is recorded.
`type`		The value must be `tomcat_access`.
`wildcard_refresh_interval`	`60s`	The interval at which wildcard file paths in `include_paths` are refreshed. Given as a time duration, for example `30s` or `2m`. This property might be useful under high logging throughputs where log files are rotated faster than the default interval.

What is logged

The logName is derived from the receiver IDs specified in the configuration. Detailed fields inside the LogEntry are as follows.

The tomcat_system logs contain the following fields in the LogEntry:

Field	Type	Description
`jsonPayload.level`	string	Log entry level
`jsonPayload.message`	string	Log message, including detailed stacktrace where provided
`jsonPayload.module`	string	Module of tomcat where the log originated
`jsonPayload.source`	string	Source of where the log originated
`severity`	string (`LogSeverity`)	Log entry level (translated).

The tomcat_access logs contain the following fields in the LogEntry:

Field	Type	Description
`httpRequest`	object	See `HttpRequest`
`jsonPayload.host`	string	Contents of the Host header
`jsonPayload.user`	string	Authenticated username for the request
`severity`	string (`LogSeverity`)	Log entry level (translated).

Configure metrics collection

To ingest metrics from Tomcat, you must create a receiver for the metrics that Tomcat produces and then create a pipeline for the new receiver.

This receiver does not support the use of multiple instances in the configuration, for example, to monitor multiple endpoints. All such instances write to the same time series, and Cloud Monitoring has no way to distinguish among them.

To configure a receiver for your tomcat metrics, specify the following fields:

Field	Default	Description
`collect_jvm_metrics`	`true`	Configures the receiver to also collect the supported JVM metrics.
`collection_interval`	`60s`	A time duration value, such as `30s` or `5m`.
`endpoint`	`localhost:8050`	The JMX Service URL or host and port used to construct the service URL. This value must be in the form of `service:jmx:<protocol>:<sap>` or `host:port`. Values in `host:port` form are used to create a service URL of `service:jmx:rmi:///jndi/rmi://<host>:<port>/jmxrmi`.
`password`		The configured password if JMX is configured to require authentication.
`type`		This value must be `tomcat`.
`username`		The configured username if JMX is configured to require authentication.

What is monitored

The following table provides the list of metrics that the Ops Agent collects from the Tomcat instance.

Metric type
Kind, Type Monitored resources	Labels
`workload.googleapis.com/tomcat.errors`
`CUMULATIVE`, `INT64` gce_instance	`proto_handler`
`workload.googleapis.com/tomcat.max_time`
`GAUGE`, `INT64` gce_instance	`proto_handler`
`workload.googleapis.com/tomcat.processing_time`
`CUMULATIVE`, `INT64` gce_instance	`proto_handler`
`workload.googleapis.com/tomcat.request_count`
`CUMULATIVE`, `INT64` gce_instance	`proto_handler`
`workload.googleapis.com/tomcat.sessions`
`GAUGE`, `DOUBLE` gce_instance
`workload.googleapis.com/tomcat.threads`
`GAUGE`, `INT64` gce_instance	`proto_handler` `state`
`workload.googleapis.com/tomcat.traffic`
`CUMULATIVE`, `INT64` gce_instance	`direction` `proto_handler`

Verify the configuration

This section describes how to verify that you correctly configured the Tomcat receiver. It might take one or two minutes for the Ops Agent to begin collecting telemetry.

To verify that Tomcat logs are being sent to Cloud Logging, do the following:

In the Google Cloud console, go to the Logs Explorer page:
Go to Logs Explorer

If you use the search bar to find this page, then select the result whose subheading is Logging.

Enter the following query in the editor, and then click Run query:

resource.type="gce_instance"
(log_id("tomcat_system") OR log_id("tomcat_access"))

To verify that Tomcat metrics are being sent to Cloud Monitoring, 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 the following query in the editor, and then click Run query:

fetch gce_instance
| metric 'workload.googleapis.com/tomcat.threads'
| every 1m

View dashboard

To view your Tomcat metrics, you must have a chart or dashboard configured. The Tomcat integration includes one or more dashboards for you. Any dashboards are automatically installed after you configure the integration and the Ops Agent has begun collecting metric data.

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, and then choose the Integrations category.
Click the name of the dashboard you want to view.

If you have configured an integration but the dashboard has not been installed, then check that the Ops Agent is running. When there is no metric data for a chart in the dashboard, installation of the dashboard fails. After the Ops Agent begins collecting metrics, the dashboard is installed for you.

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 Compute Engine deployment-platform filter.
Locate the entry for Tomcat and click View Details.
Select the Dashboards tab to see a static preview. If the dashboard is installed, then you can navigate to it by clicking View dashboard.

For more information about dashboards in Cloud Monitoring, see Dashboards and charts.

For more information about using the Integrations page, see Manage integrations.

Install alerting policies

Alerting policies instruct Cloud Monitoring to notify you when specified conditions occur. The Tomcat integration includes one or more alerting policies for you to use. You can view and install these alerting policies from the Integrations page in Monitoring.

To view the descriptions of available alerting policies and install them, 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.
Locate the entry for Tomcat and click View Details.
Select the Alerts tab. This tab provides descriptions of available alerting policies and provides an interface for installing them.
Install alerting policies. Alerting policies need to know where to send notifications that the alert has been triggered, so they require information from you for installation. To install alerting policies, do the following:
1. From the list of available alerting policies, select those that you want to install.
2. In the Configure notifications section, select one or more notification channels. You have the option to disable the use of notification channels, but if you do, then your alerting policies fire silently. You can check their status in Monitoring, but you receive no notifications.
  
  For more information about notification channels, see Manage notification channels.
3. Click Create Policies.

For more information about alerting policies in Cloud Monitoring, see Introduction to alerting.