Using OpenTelemetry to Provide Traceability for Non-Containerized Java Services#

#Overview

This solution will guide you on how to modify non-containerized Java services deployed on virtual machines or physical machines to view their invocation chains with containerized services on the platform. Please note that this solution only provides traceability functionality and does not support viewing logs.

#Prerequisites

• Your Java service is deployed on virtual or physical machines and requires traceability functionality.
• A service mesh has been created on the cluster.
• You have access to the control nodes of the Kubernetes cluster, and the kubectl tool is installed.

#Steps

#1. Download and Configure the OpenTelemetry Java Agent

First, you need to copy the OpenTelemetry Java Agent jar file to the ./agent directory on the control node of the cluster where the service mesh was created.

Select and execute the appropriate script based on the cluster's runtime component

• Containerd Runtime Component

  1. Install the nerdctl tool on the control node. Download it, extract the package, grant execution permission, and copy it to the /usr/local/bin directory:

     chmod +x nerdctl  
     cp ./nerdctl /usr/local/bin  

  2. Log in to the image repository used by the cluster, replacing <image_registry_address> with the actual address:

     nerdctl login <image_registry_address>  

  3. Run the following script to copy the Java Agent jar file from the image to the local system:

     #!/bin/sh  
     TAG=$(kubectl -n istio-system get cm otel-java-agent -oyaml | grep versions -A1 | grep -v versions | awk '{print substr($0, 7)}')  
     CONTAINERID=$(nerdctl run -d <image_registry_address>/asm/otel-java-instrumentation:$TAG sleep 9999)  
     echo "copy agent from $CONTAINERID"  
     mkdir -p agent  
     nerdctl cp $CONTAINERID:/opentelemetry-javaagent-ext.jar ./agent/opentelemetry-javaagent-ext.jar  
     nerdctl container stop $CONTAINERID  

• Docker Runtime Component

  1. Log in to the image repository used by the cluster:

     docker login <image_registry_address>

  2. Run the following script to copy the Java Agent jar file from the image to the local system:

     #!/bin/sh  
     TAG=$(kubectl -n istio-system get cm otel-java-agent -oyaml | grep versions -A1 | grep -v versions | awk '{print substr($0, 7)}')  
     CONTAINERID=$(docker run -d <image_registry_address>/asm/otel-java-instrumentation:$TAG sleep 9999)  
     echo "copy agent from $CONTAINERID"  
     mkdir -p agent  
     docker cp $CONTAINERID:/opentelemetry-javaagent-ext.jar ./agent/opentelemetry-javaagent-ext.jar  
     docker container stop $CONTAINERID  

#2. Distribute the Java Agent to Java Service Nodes

Copy the opentelemetry-javaagent-ext.jar obtained in step 1 to the ./agent directory on all nodes running Java services.

#3. Set Environment Variables

Configure the following environment variables on all Java service nodes:

#4. Modify the Java Service Startup Script

In the startup script of the Java service, add the following parameter:

-javaagent:{AGENT_PATH}/opentelemetry-javaagent-ext.jar

#5. Create a ConfigMap

In the namespace where you want to enable the traceability feature, create a ConfigMap to store the mapping between the addresses and names of non-containerized Java services. Example:

apiVersion: v1
data:
  vms: |-
    - host: 192.168.189.136
      port: 8081
      serviceName: otel-demo-consumer-vm
    - host: 192.168.189.136
      port: 9081
      serviceName: otel-demo-provider-vm
kind: ConfigMap
metadata:
  labels:
    asm.cpaas.io/vm-config-enabled: "true"
  name: virtualmachine-config

#6. Restart the Java Service

After applying the above configurations, restart the Java service to make the changes take effect.