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"
}