Application Gateway Troubleshooting

Application Gateway Troubleshooting

Overview

This runbook helps troubleshoot common Application Gateway issues including 502 Bad Gateway errors.

Prerequisites

• kubectl access to the cluster
• Ability to view pod logs

Troubleshooting Steps

Step 1: Find the Application Gateway Pod Status

Use kubectl to check if the Application Gateway pod is running:

kubectl get pods -n <namespace> | grep application-gateway

Step 2: Check Application Gateway error Logs

Review the Application Gateway error logs for any issues:

kubectl logs <application-gateway-pod> -n <namespace> --tail=100 | grep -i error

Step 3: Verify Upstream Services

Check if the upstream services that Application Gateway proxies to are healthy:

kubectl get pods -n <application-gateway-pod> -l app=upstream-service

Step 4: Check Application Gateway Configuration

Verify the Application Gateway configuration is valid:

kubectl exec <application-gateway-pod> -n <namespace> -- appg -t

Step 5: Review Service Endpoints

Ensure the Application Gateway has healthy endpoints:

kubectl get endpoints -n <namespace>

Resolution Steps

Based on findings:

• If upstream is down: Restart upstream services
• If config invalid: Fix configuration and reload
• If no endpoints: Check service selectors