Query the canary tag of requests by using OpenTelemetry SDK for Java - Microservices Engine

The underlying logic of the end-to-end canary release feature provided by Microservices Engine (MSE) is to use Application Real-Time Monitoring Service (ARMS) to perform pass-through of traffic tags. This topic describes how to obtain the current canary tag of requests from the context.

Add dependencies

Add dependencies related to OpenTelemetry to the pom.xml file.

<dependencies>
    <dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-api</artifactId>
    </dependency>
    <dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-sdk-trace</artifactId>
    </dependency>
    <dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-sdk</artifactId>
    </dependency>
</dependencies>

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-bom</artifactId>
      <version>1.23.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

Use code

Use the following code:

String tagValue = Baggage.current().getEntryValue("__microservice_tag__");

Note

The tagValue is in the JSON format. Example: [{"name":"gray","tag":"gray","priority":-1}]. In this example, name is gray. This indicates that the current context belongs to the requests that have the gray tag.
To implement this feature, you must make sure that the version of the MSE agent is 4.0 or later.