Handle connection errors

Handling connection errors is crucial when designing and implementing native applications using Microsoft Azure Cosmos DB. Connection errors occur when there is a disruption in communication between your application and the Azure Cosmos DB service. In this article, we will explore different strategies to handle connection errors effectively.

Types of Connection Errors

Before diving into the strategies, it’s important to understand the types of connection errors that can occur:

1. Transient Errors: These errors are temporary and can be caused by network glitches, server overload, or maintenance activities. Transient errors can be resolved by retrying the operation after a short delay.
2. Permanent Errors: These errors are persistent and require corrective actions such as fixing the code or configuration issues. Permanent errors may arise due to authentication failures or misconfigurations.

1. Retry Policies

Implementing retry policies helps your application automatically handle transient errors. Azure Cosmos DB SDKs provide built-in retry policies that can be configured to retry the failed operations with an exponential backoff strategy. By specifying the maximum number of retries and the wait duration between retries, you can ensure that your application doesn’t give up easily when encountering transient errors.

Here’s an example of configuring a retry policy using the Azure Cosmos DB SDK for .NET:

ConnectionPolicy connectionPolicy = new ConnectionPolicy
{
RetryOptions = new RetryOptions()
{
MaxRetryAttemptsOnThrottledRequests = 3,
MaxRetryWaitTimeInSeconds = 60
}
};

2. Circuit Breaker Pattern

The circuit breaker pattern is a design pattern that can be used to handle connection failures gracefully. It helps in preventing repeated unsuccessful attempts to connect to Azure Cosmos DB during an outage.

By implementing a circuit breaker, you can reduce the load on your application and avoid unnecessary retries. When a connection error occurs, the circuit breaker opens and subsequent requests are not attempted. After a specified timeout period, the circuit breaker closes and allows subsequent requests to be executed.

Here’s an example of implementing a circuit breaker using the Polly library in C#:

CircuitBreakerPolicy circuitBreakerPolicy = Policy
.Handle()
.CircuitBreaker(3, TimeSpan.FromSeconds(30));

3. Monitoring and Logging

Monitoring and logging are essential for tracking connection errors and diagnosing their root causes. Azure Cosmos DB provides diagnostic logs that can be configured to capture connection-related events. By analyzing these logs, you can identify patterns, troubleshoot connectivity issues, and optimize your application’s behavior.

Additionally, Azure Application Insights can be used to monitor the performance and availability of your Azure Cosmos DB resources. It provides real-time monitoring, proactive detection of issues, and insights into the health of your application.

Here’s an example of using Azure Application Insights to track connection errors:

Make sure to replace YOUR_INSTRUMENTATION_KEY with the actual instrumentation key provided by Azure Application Insights.

By implementing retry policies, circuit breakers, and monitoring/logging mechanisms, you can enhance the resilience and stability of your native applications using Azure Cosmos DB. These strategies ensure that your application can handle connection errors efficiently and provide a smooth user experience.

Remember to consult the Microsoft Azure Cosmos DB documentation for your specific SDK and programming language to ensure accurate implementation and utilization of the provided features and functionalities.