# Report on the Implementation of the Retry Pattern in FastAPI Server for Database Connections

## Introduction

In our current FastAPI server implementation, we have integrated the Retry Pattern as a key resilience mechanism for managing database connections. This pattern plays a crucial role in enhancing the stability and reliability of our server by addressing transient failures in database connectivity.

## Overview of the Retry Pattern

The Retry Pattern is a resilience strategy used in software systems to handle transient failures by automatically retrying a failed operation. This pattern is particularly effective for operations that have a high likelihood of success on subsequent attempts, such as temporary network glitches or brief database unavailability.

## Implementation in FastAPI

### Context

Our FastAPI server relies on consistent and reliable database connectivity to perform various operations. Given the nature of network communication and database interactions, transient failures are not uncommon. These failures, while temporary, can disrupt the user experience and affect the overall performance of the application.

### Application of the Retry Pattern

We have implemented the Retry Pattern in the following manner:

- Failure-Prone Operation: The primary operation where the Retry Pattern is applied is the database connection initiation process. Whenever our FastAPI server attempts to establish a connection with the database, this operation is considered potentially susceptible to transient failures.

- Retry Logic: The logic includes:
- Max Retries: We have configured a maximum of 5 retry attempts to prevent indefinite retrying.
- Backoff Strategy: The implementation uses an exponential backoff strategy with a base delay of 500 milliseconds. The delay increases with each retry attempt according to the formula: `50 * (2 ** retry_count) ms`.

- Error Handling: The system differentiates between transient and non-transient failures. Transient failures trigger the retry mechanism, while non-transient failures (like authentication errors) are handled differently to avoid unnecessary retries.

### Benefits Observed

Since the integration of the Retry Pattern, we have observed:
- Improved System Availability: The server maintains higher availability as it can recover from temporary database connectivity issues without manual intervention.
- Enhanced User Experience: Users experience fewer errors related to database connectivity, leading to a smoother interaction with our services.

## Conclusion

The implementation of the Retry Pattern for database connections in our FastAPI server has significantly contributed to the resilience and reliability of our application. It ensures that temporary issues do not disproportionately impact the user experience or the system's performance.