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DBZ-2862 Installation and configuration of OpenTelemetry to enable tr…
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vidourem authored and jpechane committed Oct 26, 2023
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2 changes: 1 addition & 1 deletion documentation/modules/ROOT/nav.adoc
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** xref:integrations/serdes.adoc[Change Event SerDes]
** xref:integrations/outbox.adoc[Outbox Quarkus Extension]
** xref:integrations/cloudevents.adoc[CloudEvents]
** xref:integrations/tracing.adoc[OpenTracing]
** xref:integrations/tracing.adoc[OpenTelemetry]
** xref:integrations/testcontainers.adoc[Integration Testing with Testcontainers]
* Operations
** xref:operations/debezium-server.adoc[Debezium Server]
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5 changes: 1 addition & 4 deletions documentation/modules/ROOT/pages/integrations/outbox.adoc
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|===

=== Distributed tracing
[NOTE]
====
This feature is currently in incubating state, i.e. exact semantics, configuration options etc. may change in future revisions, based on the feedback we receive. Specifically, Distributed Tracing support will be replaced with support for the Open Telemetry specification in a future release.
====

The extension has support for the distributed tracing.
See link:/documentation/reference/integrations/tracing[tracing documentation] for more details.
138 changes: 115 additions & 23 deletions documentation/modules/ROOT/pages/integrations/tracing.adoc
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toc::[]

[IMPORTANT]
====
*THIS DOCUMENTATION IS OBSOLETE.*
OpenTracing project is discontinued and OpenTelemetry is its successor.
As of Debezium 2.4.0.Alpha2, Debezium has switched from OpenTracing to OpenTelemetry framework.
However, we unfortunately haven't managed to update the documentation before the release.
We applogize for this dire situation and hope we will fix it ASAP.
====

== Overview

Observability is an important aspect of microservice-oriented applications.
One of the key ingredients for observability is https://microservices.io/patterns/observability/distributed-tracing.html[distributed tracing].

It is necessary to provide additional precautions when an application writes a record to a database that is later processed by Debezium.
The active trace is effectively demarcated by the write to the database.
If we want Debezium to join the larger scope application tracer we need to pass the trace metadata to Debezium.
If you want to include {prodname} data in your application tracer, you must pass the trace metadata to {prodname}.

You can add tracing support to {prodname} through the https://opentelemetry.io/docs/specs/otel/[OpenTelemetry specification].

== Installation

To enable traceability in {prodname}, you must install the required OpenTelemetry API packages on your Kafka Connect cluster, together with the OpenTelemetry SDK.

There are three main methods for installing OpenTelemetry on Kafka Connect, each having its advantages:

xref:open-telemetry-manual-installation[Manual installation]:: Offers more control and customization.
xref:open-telemetry-docker-installation[Docker installation]:: Provides easier integration.
xref:open-telemetry-strimzi-installation[Strimzi installation]:: Presents a ready-to-use solution on Kubernetes that includes all of the necessary OpenTelemetry components.

The tracing support is added to Debezium through the https://opentracing.io/[OpenTracing] specification.
It is also necessary to provide a client implementing the specification.
Debezium was tested with https://www.jaegertracing.io/[Jaeger] implementation.
[id="open-telemetry-manual-installation"]
=== Manual installation of OpenTelemetry

[WARNING]
A manual installation provides greater control and customization.

==== Installing the OpenTelemetry API

Install the following packages to the Kafka Connect classpath:

* https://mvnrepository.com/artifact/io.opentelemetry/opentelemetry-api/[opentelemetry-api]
* https://mvnrepository.com/artifact/io.opentelemetry/opentelemetry-context/[opentelemetry-context]
* https://mvnrepository.com/artifact/io.opentelemetry/opentelemetry-semconv/[opentelemetry-semconv]
* https://mvnrepository.com/artifact/io.opentelemetry.instrumentation/opentelemetry-instrumentation-api/[opentelemetry-instrumentation-api]
* https://mvnrepository.com/artifact/io.opentelemetry.instrumentation/opentelemetry-instrumentation-api-semconv/[opentelemetry-instrumentation-api-semconv]
* https://mvnrepository.com/artifact/io.opentelemetry.instrumentation/opentelemetry-kafka-clients-2.6/[opentelemetry-kafka-clients-2.6]
* https://mvnrepository.com/artifact/io.opentelemetry.instrumentation/opentelemetry-kafka-clients-common/[opentelemetry-kafka-clients-common]


You can download the OpenTelemetry packages directly from the Maven repository, or retrieve the packages by using the Maven dependency plugin to ensure version compatibility.

===== Using the Maven Dependency Plugin

1. Create a POM file similar to the one in the following example.
In your version of the file, specify the version of the OpenTelemetry package that you want to use.
+
[source,xml]
----
<?xml version="1.0"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>group.id</groupId>
<artifactId>artifact-id</artifactId>
<version>0.0.1</version>
<properties>
<version.opentelemetry.api>1.23.1</version.opentelemetry.api>
<version.opentelemetry.kafka.clients.2.6>1.23.0-alpha</version.opentelemetry.kafka.clients.2.6>
</properties>
<dependencies>
<dependency>
<groupId>io.opentelemetry</groupId>
<artifactId>opentelemetry-api</artifactId>
<version>${version.opentelemetry.api}</version>
</dependency>
<dependency>
<groupId>io.opentelemetry.instrumentation</groupId>
<artifactId>opentelemetry-kafka-clients-2.6</artifactId>
<version>${version.opentelemetry.kafka.clients.2.6}</version>
</dependency>
</dependencies>
</project>
----
+
2. In the directory that contains the `pom.xml` file, run the following command to download all dependencies (including transitives) to a specified directory (for example, `./lib`)
+
[source,bash]
----
mvn dependency:copy-dependencies -DoutputDirectory=./lib
----


==== Installing the OpenTelemetry SDK
After you install the API, install the OpenTelemetry SDK.
Install the OpenTelemetry SDK on your Kafka connect cluster by using the https://opentelemetry.io/docs/instrumentation/java/automatic/[Java agent] for automatic instrumentation.

[id="open-telemetry-docker-installation"]
=== Using Docker to install OpenTelemetry
Prefer this installation method if you want to use Docker for local development or testing.

The OpenTelemetry API dependencies are installed in the https://quay.io/repository/debezium/connect[{prodname} Kafka Connect] container image.
The JAR files are downloaded to a separate directory.
By default, the JAR files are not added to the class path.
To add the JAR files to the class path, set the environment variable `ENABLE_OTEL` to `true`.
You must also install the https://opentelemetry.io/docs/instrumentation/java/automatic/[OpenTelemetry Java agent].

[id="open-telemetry-strimzi-installation"]
=== Using Strimzi to install Open Telemetry
https://strimzi.io/[Strimzi] provides a way to deploy an Apache Kafka cluster on Kubernetes.

The Strimzi Kafka image includes all of the necessary OpenTelemetry components.

If you want to view the OpenTelemetry components that are available in the Strimzi image, examine the compose file that is provided in the https://github.com/debezium/debezium-examples/tree/main/outbox[{prodname} Outbox example].

=== Configuring OpenTelemetry

For information about how to configure OpenTelemetry, see the https://opentelemetry.io/docs/instrumentation/java/automatic/agent-config/[OpenTelemetry documentation].

[NOTE]
====
Neither the specification JAR files nor the Jaeger client are part of the Debezium Kafka Connect container image.
The user either needs to extend the image with them or can use the https://strimzi.io/[Strimzi] Kafka image.
In that case, the tracing of Kafka producer and consumer is also available.
{prodname} was tested with a {prodname} Kafka Connect image, and a Strimzi distribution that included the following configuration settings:
* `otel.traces.exporter=otlp`
* `otel.propagators=tracecontext`
See compose file of https://github.com/debezium/debezium-examples/tree/main/outbox[Outbox example].
====

== ActivateTracingSpan SMT
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=== Kafka Producer tracing

Optionally it is possible to enable tracing at the Kafka producer level.
If enabled then when the message is being written to the Kafka broker the producer will extract Debezium's processing span context from the Kafka message headers, create a new child span and record information about the write to the broker.
If you enable tracing in the Kafka producer, when messages are written to the Kafka broker, the producer extracts the {prodname} processing span context from the Kafka message headers, creates a new child span, and then records information about the write operation to the broker.
Then it injects the new span into the message headers so a consumer of the message can restore the trace and resume end-to-end tracing.

The interceptor cannot propagate the traceability context if the Kafka instrumentation is enabled.
The interceptor simply propagates the traceability context before delegating the instrumentation to the OpenTelemetry SDK.

==== Enabling end-to-end traceability

1. Download and install the https://mvnrepository.com/artifact/io.debezium/debezium-interceptor/[debezium-interceptor] to the Kafka Connect classpath.
2. Disable the automatic OpenTelemetry instrumentation at the Kafka producer and consumer by setting the value of `otel.instrumentation.common.default-enabled` to `false`.

=== Configuration options

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* inject the span context into that `java.util.Properties` instance that is serialized into the `tracingspancontext` column
* write the record into the database

The tracing integration in the outbox extension is automatically enabled if also the `smallrye-opentracing` Quarkus extension is present.
If you want to disable tracing support for the outbox extension despite the `smallrye-opentracing` Quarkus extension being is present,
you can disable it by setting an option `quarkus.debezium-outbox.tracing.enabled=false` in the Quarkus `application.properties` file.
The tracing integration in the outbox extension is automatically enabled if the `quarkus-opentelemetry` extension is present.
If you want to disable tracing support for the outbox extension despite the presence of the `quarkus-opentelemetry` extension,
set the option `quarkus.debezium-outbox.tracing.enabled=false` in the Quarkus `application.properties` file.

== Event Router SMT

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