Observability for Legacy Spring Apps - No Code Changes Required

apiVersion: v1
kind: ConfigMap
metadata:
  name: otel-java-agent-config
data:
  agent.properties: |
    otel.instrumentation.jdbc.enabled=true
    otel.instrumentation.spring-webmvc.enabled=true

  # Optional: customize logback configuration
  logback.xml: |
    <configuration>
        <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
            <encoder>
                <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
            </encoder>
        </appender>

        <root level="INFO">
            <appender-ref ref="STDOUT" />
        </root>
    </configuration>

# omitted    for brevity

      # volumes
      volumes:
        - name: otel-agent
          emptyDir: {} # or { medium: Memory } for tmpfs
        - name: otel-agent-config        # optional
          configMap:
            name: otel-java-agent-config
            items:
              - key: agent.properties
                path: agent.properties
              - key: logback.xml
                path: logback.xml
      initContainers:
        # omitted for brevity. See previous section for details.

      containers:
        - name: app
          image: credemol/postgresql-example:0.1.0
          ports:
            - containerPort: 8080
              name: http
              protocol: TCP
            # Metrics endpoint for Target Allocator to scrape
            - containerPort: 9464
              name: metrics
              protocol: TCP
          #
          volumeMounts:
            - name: otel-agent
              mountPath: /otel/agent
              readOnly: true
            - name: otel-agent-config      # optional
              mountPath: /otel/config
              readOnly: true
          env:
            # 1) Inject the javaagent
            - name: JAVA_TOOL_OPTIONS
              value: "-javaagent:/otel/agent/opentelemetry-javaagent.jar"
            - name: OTEL_JAVAAGENT_EXTENSIONS
              value: "/otel/agent/nsa2-otel-extension-1.0-all.jar"

            # 2) Core OTel config
            - name: OTEL_SERVICE_NAME
              value: "postgresql-example"
            - name: OTEL_EXPORTER_OTLP_ENDPOINT
              value: "http://otel-collector.o11y.svc.cluster.local:4317"
            - name: OTEL_EXPORTER_OTLP_PROTOCOL
              value: "grpc"
            - name: OTEL_METRICS_EXPORTER
              value: "prometheus"

            # (Optional) add metadata & sampling
            - name: OTEL_RESOURCE_ATTRIBUTES
              value: "service.namespace=default,service.version=1.0.0,env=dev"
            - name: OTEL_TRACES_SAMPLER
              value: "parentbased_traceidratio"
            - name: OTEL_TRACES_SAMPLER_ARG
              value: "1.0"  # 100% sampling for troubleshooting

            # (Optional) point agent to a properties file
            - name: OTEL_JAVAAGENT_CONFIGURATION_FILE
              value: "/otel/config/agent.properties"

          envFrom:
            - configMapRef:
                name: postgresql-example-configmap
                optional: true
            - secretRef:
                name: postgresql-example-secret
                optional: true
          resources:
            requests: { cpu: "100m", memory: "256Mi" }
            limits:   { cpu: "1000m", memory: "1024Mi" }