observability

Observability: A Camel Quarkus example

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Tip	Check the Camel Quarkus User guide for prerequisites and other general information.

Start in the Development mode

$ mvn clean compile quarkus:dev

The above command compiles the project, starts the application and lets the Quarkus tooling watch for changes in your workspace. Any modifications in your project will automatically take effect in the running application.

Tip	Please refer to the Development mode section of Camel Quarkus User guide for more details.

Enabling metrics

To enable observability features in Camel Quarkus, we need to add some additional dependencies to the project’s pom.xml file. The most important one for metrics is camel-quarkus-micrometer:

<dependency>
    <groupId>org.apache.camel.quarkus</groupId>
    <artifactId>camel-quarkus-micrometer</artifactId>
</dependency>

After adding this dependency, you can benefit from both of the Camel Micrometer and Quarkus Micrometer worlds. We are able to use multiple ways of creating meters for our custom metrics.

First using Camel micrometer component (see Routes.java):

.to("micrometer:counter:org.acme.observability.greeting-provider?tags=type=events,purpose=example")

Which will count each call to the platform-http:/greeting-provider endpoint.

The second approach is to benefit from CDI dependency injection of the MeterRegistry:

@Inject
MeterRegistry registry;

Then using it directly in a Camel Processor method to publish metrics:

void countGreeting(Exchange exchange) {
    registry.counter("org.acme.observability.greeting", "type", "events", "purpose", "example").increment();
}

from("platform-http:/greeting")
    .removeHeaders("*")
    .process(this::countGreeting)

This counts each call to the platform-http:/greeting endpoint.

Finally, the last approach is to use Micrometer annotations, by defining a bean TimerCounter.java as follows:

@ApplicationScoped
@Named("timerCounter")
public class TimerCounter {

    @Counted(value = "org.acme.observability.timer-counter", extraTags = { "purpose", "example" })
    public void count() {
    }
}

It can then be invoked from Camel via the bean EIP (see TimerRoute.java):

.bean("timerCounter", "count")

It will increment the counter metric each time the Camel timer is fired.

Browsing metrics

Metrics are exposed on an HTTP endpoint at /q/metrics on port 9000.

Note	Note we are using a different port (9000) for the management endpoint then our application (8080) is listening on. This is configured in applcation.properties via quarkus.management.enabled = true. See the Quarkus management interface guide for more information.

To view all Camel metrics do:

$ curl -s localhost:9000/q/metrics

To view only our previously created metrics, use:

$ curl -s localhost:9000/q/metrics | grep -i 'purpose="example"'

and you should see 3 lines of different metrics (with the same value, as they are all triggered by the timer).

Note	Maybe you’ve noticed the Prometheus output format. If you would rather use the JSON format, please follow the Quarkus Micrometer management interface configuration guide.

Health endpoint

Camel provides some out of the box liveness and readiness checks. To see this working, interrogate the /q/health/live and /q/health/ready endpoints on port 9000:

$ curl -s localhost:9000/q/health/live

$ curl -s localhost:9000/q/health/ready

The JSON output will contain a checks for verifying whether the CamelContext and each individual route is in the 'Started' state.

This example project contains a custom liveness check class CustomLivenessCheck and custom readiness check class CustomReadinessCheck which leverage the Camel health API. You’ll see these listed in the health JSON as 'custom-liveness-check' and 'custom-readiness-check'. On every 5th invocation of these checks, the health status of custom-liveness-check will be reported as DOWN.

You can also directly leverage MicroProfile Health APIs to create checks. Class CamelUptimeHealthCheck demonstrates how to register a readiness check.

Tracing

To be able to diagnose problems in Camel Quarkus applications, you can start tracing messages. We will use OpenTelemetry standard suited for cloud environments.

All you need is to add the camel-quarkus-opentelemetry dependency to your project pom.xml:

<dependency>
    <groupId>org.apache.camel.quarkus</groupId>
    <artifactId>camel-quarkus-opentelemetry</artifactId>
</dependency>

Then configure the OpenTelemetry exporter in application.properties:

# We are using a property placeholder to be able to test this example in convenient way in a cloud environment
quarkus.otel.exporter.otlp.traces.endpoint = http://${TELEMETRY_COLLECTOR_COLLECTOR_SERVICE_HOST:localhost}:4317

Note	For information about other OpenTelemetry exporters, refer to the Camel Quarkus OpenTelemetry extension documentation.

To view tracing events, start a tracing server. A simple way of doing this is with Docker Compose:

$ docker-compose up -d

With the server running, browse to http://localhost:16686. Then choose 'camel-quarkus-observability' from the 'Service' drop down and click the 'Find Traces' button.

The platform-http consumer route introduces a random delay to simulate latency, hence the overall time of each trace should be different. When viewing a trace, you should see a hierarchy of 6 spans showing the progression of the message exchange through each endpoint.

Package and run the application

Once you are done with developing you may want to package and run the application.

Tip	Find more details about the JVM mode and Native mode in the Package and run section of Camel Quarkus User guide

JVM mode

$ mvn clean package
$ java -jar target/quarkus-app/quarkus-run.jar
...
[io.quarkus] (main) camel-quarkus-examples-... started in 1.163s. Listening on: http://0.0.0.0:8080

Native mode

Important

Native mode requires having GraalVM and other tools installed. Please check the Prerequisites section of Camel Quarkus User guide.

To prepare a native executable using GraalVM, run the following command:

$ mvn clean package -Pnative
$ ./target/*-runner
...
[io.quarkus] (main) camel-quarkus-examples-... started in 0.013s. Listening on: http://0.0.0.0:8080
...

Feedback

Please report bugs and propose improvements via GitHub issues of Camel Quarkus project.