Overview of Troubleshooting
This guide provides steps and best practices for diagnosing and resolving common issues with Azure App Services. Understanding the underlying components and utilizing the available tools is crucial for efficient problem-solving.
Key areas to focus on include:
- Application errors
- Performance bottlenecks
- Deployment failures
- Networking connectivity
- Resource utilization
Common Issues and Solutions
Check application logs for unhandled exceptions. Ensure your application is correctly configured in the App Service settings (e.g., startup command, environment variables). Scale up your App Service Plan if resource constraints are suspected.
These often indicate server-side issues. Review the App Service diagnostics for HTTP error logs. Verify that your application code is deployed correctly and dependencies are met. For persistent errors, consider enabling detailed error logging for your application framework.
Analyze application performance metrics. Identify slow database queries or external API calls. Optimize your code for efficiency and consider enabling caching strategies. Scale out your App Service Plan or use autoscale rules.
Performance Tuning
Performance issues can stem from various factors. Here are common areas to investigate:
Monitor CPU and Memory usage in the Azure portal. If consistently high, identify resource-intensive parts of your application. Profiling tools can help pinpoint exact bottlenecks.
Consider upgrading your App Service Plan tier or scaling out instances.
Slow database queries are a frequent cause of poor application performance. Use database profiling tools and analyze query execution plans. Ensure proper indexing is in place.
Calls to external APIs or services can introduce latency. Implement timeouts, retries, and consider asynchronous patterns.
Deployment Errors
Deployment issues can prevent your application from running or updating correctly.
Always check the deployment logs in Azure DevOps or your CI/CD pipeline. These logs provide detailed information about build failures or deployment script errors.
Ensure that application settings, connection strings, and environment variables in Azure App Services match your local development environment and deployment configurations.
If deployment succeeds but the application fails to start, review the App Service logs (Kudu, Log Stream) for runtime exceptions. Common causes include missing dependencies, incorrect runtime versions, or misconfigured startup commands.
Networking Problems
Connectivity issues can affect access to your App Service or its dependencies.
Ensure that any network security groups (NSGs) or Azure Firewall rules allow traffic to and from your App Service, especially if it's integrated with a virtual network.
Verify that your App Service is accessible over the internet or through private endpoints as intended. Check access restrictions and custom domain configurations.
If using VNet integration, ensure the subnet is correctly configured and accessible. Check routes and DNS resolution within the virtual network.
Log Analysis
Effective log analysis is key to identifying the root cause of issues.
Enable application logging in your App Service. You can view logs in real-time using the "Log stream" feature in the Azure portal or download them for deeper analysis.
Common log locations:
/site/wwwroot/log(for file-based logs)- Application-specific logging outputs
These logs capture HTTP requests and responses, useful for diagnosing client-side issues or errors related to web server configuration.
Azure App Services provide comprehensive diagnostic logs, including request logs, error logs, and deployment logs.
Diagnostic Tools
Azure provides several built-in tools to aid in troubleshooting.
Navigate to your App Service in the Azure portal and select "Diagnose and solve problems". This tool can automatically detect and suggest solutions for common issues like availability, performance, and configuration problems.
Access the Kudu console (https://your-app-name.scm.azurewebsites.net) for advanced diagnostics. You can browse files, view environment variables, run commands, and access diagnostic tools.
For .NET, Java, Node.js, and Python applications, integrate Application Insights for deep performance monitoring, live metrics, failure analysis, and dependency tracking.
Example instrumentation key:
a1b2c3d4-e5f6-7890-1234-567890abcdef
Under "Advanced Tools" in the portal, you can find tools like the Process Explorer and Debugging tools to inspect running processes and debug live applications.