To integrate JMX metrics from your Tomcat application running in AWS App Runner with CloudWatch, you'll need to work within the constraints of the managed nature of App Runner, which does not expose the underlying instances for direct configuration like ECS or EC2 does. However, you can still export JMX metrics and push them to CloudWatch in a few steps.

Here’s a potential solution:

1. Use JMX Exporter (Prometheus JMX Exporter) The JMX exporter is a Java agent that can scrape and expose JMX metrics over HTTP in a format that Prometheus can scrape. It can also integrate with CloudWatch through the CloudWatch Agent.

Steps to integrate JMX Exporter with your App Runner container: Add the JMX Exporter to your Docker Container: You can add the JMX exporter to your Tomcat container by downloading the JMX exporter Java agent and including it in your Dockerfile. Here’s how you can modify your Dockerfile to add it:

Dockerfile Copy Edit FROM amazoncorretto:11

Install JMX exporter jar

ADD jmx_exporter.jar /opt/jmx_exporter/jmx_exporter.jar

Start Tomcat with JMX Exporter

CMD ["java", "-javaagent:/opt/jmx_exporter/jmx_exporter.jar=8080:/opt/jmx_exporter/config.yml", "-jar", "your-tomcat-application.jar"] The config.yml file should be configured to specify which JMX beans to scrape. The JMX exporter will expose these metrics on an HTTP endpoint.

Expose the JMX Exporter HTTP Endpoint: The JMX exporter will expose the metrics via an HTTP endpoint, such as http://localhost:8080/metrics. You need to ensure that this endpoint is exposed to the public so that AWS CloudWatch can scrape it.

Since App Runner containers are abstracted, you cannot directly expose this endpoint to the internet in the same way you would with ECS or EC2 instances. However, you can work around this by setting up an intermediary service, such as a CloudWatch Agent or Prometheus itself, to scrape the metrics.

2. Use CloudWatch Agent (Container Insights) AWS App Runner does not provide direct access to install and configure CloudWatch Agent on the underlying EC2 instances. However, you can make use of AWS CloudWatch Container Insights for monitoring containerized applications running on App Runner.

Unfortunately, as of now, App Runner does not natively support scraping Prometheus endpoints directly with CloudWatch Agent (which would be a common solution in ECS). But you can try the following approach:

Use Amazon Managed Prometheus: You can configure your App Runner application to expose metrics in Prometheus format (via JMX Exporter). Then, you can integrate AWS Managed Prometheus to scrape the exposed endpoint.

Set up Amazon Managed Prometheus.

Configure it to scrape metrics from your App Runner service by specifying the endpoint (http://localhost:8080/metrics).

Once the metrics are in Prometheus, you can configure Prometheus to send these metrics to CloudWatch.

3. Leverage CloudWatch Logs Alternatively, if Prometheus scraping is not an option, you can configure your application to send logs (including JMX-related logs) to CloudWatch Logs. From there, you can create custom metrics based on log data.

Configure Tomcat to Log JMX Stats: You can configure Tomcat or your application to log JMX stats to the console.

Enable CloudWatch Logs for App Runner: Configure your App Runner service to send logs to CloudWatch.

Create Custom CloudWatch Metrics: Once the logs are in CloudWatch, you can create custom metrics based on the logs (e.g., using metric filters) for things like memory usage, thread counts, and other JMX metrics.

Conclusion: While AWS App Runner does not expose underlying EC2 instances for direct management or allow the installation of CloudWatch Agent or Prometheus directly, you can still achieve visibility into JMX metrics by using solutions like:

JMX Exporter to expose metrics in Prometheus format and then scrape them with AWS Managed Prometheus.

Use CloudWatch Logs to capture JMX stats and create custom metrics based on those logs.

For now, integrating Prometheus via an intermediary service like AWS Managed Prometheus or leveraging CloudWatch Logs for log-based metrics would be the most feasible approach in App Runner.