Resilience .NETCore

A simple POC using Polly to deal with resilience.

Timeout
Retry
Circuit Breaker
Fallback

Running without API

With Powershell run dotnet run into ResilienceSample folder.

Now listening on: http://localhost:5001

Request http://localhost:5001/api/values on browser and look at the logs on Powershell. It will try to connect on http://localhost:5880/api/products/:productId

It will try 3 request with an interval of 2 seconds each before open the circuit and will return fallback result.

Logs:

11:58:52 - Error: [ProductClient.GetAsync]: No connection could be made because the target machine actively refused it
11:58:52 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 1
11:58:54 - Error: [ProductClient.GetAsync]: No connection could be made because the target machine actively refused it
11:58:54 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 2
11:58:56 - Error: [ProductClient.GetAsync]: No connection could be made because the target machine actively refused it
11:58:56 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 3
11:58:56 - Failed! Circuit open, waiting: 00:00:30
11:58:56 - Fallback method used due to: The circuit is now open and is not allowing calls.

Until 30 seconds, if you request again the logs will be the same and the service will not call the WebApi http://localhost:5880/api/products/:productId
After 30 seconds, if you request again, the circuit state will be half open and will try to request again

Logs:

12:36:02 - Circuit is half open.
12:36:04 - Error: [ProductClient.GetAsync]: No connection could be made because the target machine actively refused it
12:36:04 - Failed! Circuit open, waiting: 00:00:30
12:36:04 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 1
12:36:06 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 1
12:36:08 - Request failed. Waiting 00:00:02 before next retry. Retry attempt 1
12:36:10 - Fallback method used due to: The circuit is now open and is not allowing calls.

When WebApi is back, the circuit is reseted and the service works properly and return expected result

Logs:

12:40:10 - Circuit is reset.

Running with API

With Powershell run dotnet run into WebApi folder.

Now listening on: http://localhost:5880
Application started. Press Ctrl+C to shut down.

Using a new instance of Powershell, run dotnet run into ResilienceSample folder.

Now listening on: http://localhost:5001

Request http://localhost:5001/api/values on browser and it will return the expect result from http://localhost:5880/api/products/:productId

{
    "id": 123456,
    "name": "Product"
}