Updates

Author: andytael

docs-source/site/docs/platform/eureka.md

@@ -80,6 +80,180 @@ server.features.eureka.client.fetch-registry=true
 server.features.eureka.instance.preferIpAddress=true
 ```
 
+## Testing and Debugging
+
+### Verify Eureka Server is Running
+
+Check that the Eureka server pod is running and healthy:
+
+```bash
+kubectl get pods -n eureka
+```
+
+Expected output:
+
+```text
+NAME                      READY   STATUS    RESTARTS   AGE
+eureka-7b8f9d5c4d-x9k2m   1/1     Running   0          5m
+```
+
+Check the Eureka service:
+
+```bash
+kubectl get svc -n eureka
+```
+
+Expected output:
+
+```text
+NAME     TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
+eureka   ClusterIP   10.96.123.456   <none>        8761/TCP   5m
+```
+
+### Test Service Registration
+
+After deploying an application configured to register with Eureka, verify it appears in the Eureka registry:
+
+**Option 1: Using the Eureka Web UI**
+
+1. Port-forward to Eureka:
+   ```bash
+   kubectl port-forward -n eureka svc/eureka 8761
+   ```
+
+2. Open [http://localhost:8761](http://localhost:8761) in your browser
+
+3. Check the "Instances currently registered with Eureka" section. Your application should appear under "Application" with its name in uppercase
+
+**Option 2: Using Eureka REST API**
+
+Query the Eureka REST API to see all registered services:
+
+```bash
+kubectl port-forward -n eureka svc/eureka 8761 &
+curl -s http://localhost:8761/eureka/apps | grep -i "<app>"
+```
+
+Or check a specific application:
+
+```bash
+curl -s http://localhost:8761/eureka/apps/YOUR-APPLICATION-NAME
+```
+
+### Common Issues and Debugging
+
+#### Services Not Appearing in Eureka
+
+**Check application logs for registration errors:**
+
+```bash
+kubectl logs -n <your-namespace> <your-pod-name> | grep -i eureka
+```
+
+**Common causes:**
+
+1. **Incorrect Eureka URL:** Verify the `eureka.client.service-url.defaultZone` property points to the correct Eureka service URL (typically `http://eureka.eureka:8761/eureka`)
+
+2. **Network connectivity:** Test connectivity from your application pod to Eureka:
+   ```bash
+   kubectl exec -n <your-namespace> <your-pod-name> -- curl -v http://eureka.eureka:8761/eureka/apps
+   ```
+
+3. **Missing dependencies:** Ensure the Eureka client dependency is included in your application
+
+4. **Registration disabled:** Check that `eureka.client.register-with-eureka` is set to `true`
+
+#### Service Registration Delays
+
+Eureka uses a heartbeat mechanism with default intervals:
+- **Registration delay:** Up to 30 seconds after application startup
+- **Discovery delay:** Up to 30 seconds for other services to discover the new instance
+- **Deregistration delay:** Up to 90 seconds after an instance goes down
+
+To reduce these delays for development/testing, add to your application configuration:
+
+```yaml
+eureka:
+  instance:
+    lease-renewal-interval-in-seconds: 5
+    lease-expiration-duration-in-seconds: 10
+  client:
+    registry-fetch-interval-seconds: 5
+```
+
+:::warning
+Do not use these shortened intervals in production as they increase network traffic and server load.
+:::
+
+#### Check Eureka Server Logs
+
+View Eureka server logs to diagnose registration or discovery issues:
+
+```bash
+kubectl logs -n eureka -l app=eureka --tail=100 -f
+```
+
+Look for:
+- Registration events: `Registered instance ... with status UP`
+- Heartbeat failures: `Lease expired for ...`
+- Replication errors (if running multiple Eureka servers)
+
+#### Verify Environment Variables
+
+Check that the Eureka environment variables are correctly injected into your application pod:
+
+```bash
+kubectl exec -n <your-namespace> <your-pod-name> -- env | grep -i eureka
+```
+
+Expected variables:
+```text
+EUREKA_SERVICE_URL=http://eureka.eureka:8761/eureka
+```
+
+#### Application Shows as DOWN in Eureka
+
+**Possible causes:**
+
+1. **Health check endpoint failing:** Verify your application's health endpoint is responding:
+   ```bash
+   kubectl exec -n <your-namespace> <your-pod-name> -- curl http://localhost:<port>/actuator/health
+   ```
+
+2. **Incorrect health check URL:** Check the `eureka.instance.health-check-url-path` configuration
+
+3. **Application startup incomplete:** The application may still be initializing
+
+#### Multiple Instances Not Load Balancing
+
+If you have multiple instances of a service but requests always go to the same instance:
+
+1. **Verify all instances are registered:**
+   ```bash
+   curl -s http://localhost:8761/eureka/apps/YOUR-SERVICE-NAME | grep instanceId
+   ```
+
+2. **Check load balancer configuration:** Ensure your client is using a load-balanced RestTemplate or WebClient (for Spring Boot)
+
+3. **Verify client-side load balancing:** Spring Cloud LoadBalancer should be on the classpath
+
+### Enable Debug Logging
+
+To get more detailed Eureka logs in your application, add to your `application.yaml`:
+
+```yaml
+logging:
+  level:
+    com.netflix.discovery: DEBUG
+    com.netflix.eureka: DEBUG
+```
+
+For the Eureka server, edit the deployment and add environment variables:
+
+```bash
+kubectl set env deployment/eureka -n eureka LOGGING_LEVEL_COM_NETFLIX_EUREKA=DEBUG
+```
+
 ## Getting Help
 
 - [#oracle-db-microservices Slack channel](https://oracledevs.slack.com/archives/C06L9CDGR6Z) in the Oracle Developers slack workspace.