How to specify AWS credentials in C# .NET core console program

I am trying to test a .NET core console program to publish a message to SNS. As I had issues trying to get it to work in Lambda, I want to try it in a non-Lambda environment. In Lambda, security is covered by the role, but in a console program, I presume that I have to specify my access key and secret somehow.

I've read this page: http://docs.aws.amazon.com/sdk-for-net/v3/developer-guide/net-dg-config-creds.html#net-dg-config-creds-sdk-store, but still totally confused.

I'm running on my local development computer, not an EC2 instance. No intent to go to production with this, just trying to test some code.

I'm on Visual Studio 2015, .NET Core 1.0. I've used Nuget to get the following: "AWSSDK.Extensions.NETCore.Setup": "3.3.3", "AWSSDK.SimpleNotificationService": "3.3.0.23",

Based on the answer to How to set credentials on AWS SDK on NET Core? I created the /user/.aws/credentials file (assuming credentials was the file name and not the directory name).

But that question/answer doesn't address how to actually use this file. The code I'm running is below.

    public static void Main(string[] args)
    {
        Console.WriteLine("Started");
        //var awsCredentials = new Amazon.Runtime.AWSCredentials()
        var client = new Amazon.SimpleNotificationService.AmazonSimpleNotificationServiceClient(Amazon.RegionEndpoint.EUWest2);
        //var client = new Amazon.SimpleNotificationService.AmazonSimpleNotificationServiceClient(awsCredentials, Amazon.RegionEndpoint.EUWest2);
        //Amazon.SimpleNotificationService.Model.PublishResponse publishResp = null;
        SendMessage(client).Wait();
        Console.WriteLine("Completed call to SendMessage: Press enter to end:");
        Console.ReadLine(); 
    }

The error I'm getting on the new client is:

An unhandled exception of type 'Amazon.Runtime.AmazonServiceException' occurred in AWSSDK.Core.dll

Additional information: Unable to find credentials

I see there is a way to pass an AWSCredentials object to that constructor, but I don't understand how to build it. Amazon.Runtime.AWSCredentials is an abstract class, so I can't use it in a "new" statement.

Solution

Based on Dan Pantry's answer, here is a simple short answer with code highlighted (note the region enum in the second line):

var awsCredentials = new Amazon.Runtime.BasicAWSCredentials("myaccesskey", "mysecretkey"); 
var client = new Amazon.SimpleNotificationService.AmazonSimpleNotificationSer‌viceClient(
                              awsCreden‌tials, Amazon.RegionEndpoint.EUWest2);

Use a role if possible, but above works when needed. Then the question is where to store the access key/secret key; could be environment variable, config file, prompt the user, or any of the usual suspects.

AWS-CLI and Python use credentials from here: c:\Users\username\.aws\credentials, so the C# could just read that file so as not to put the codes in the C# program itself. But then each user/developer that runs the program would need to set their credentials there.

There is also now a concept of running Lambda on your local machine, but I haven't tried it yet: https://dzone.com/articles/run-aws-lambda-functions-locally-on-windows-machin#:~:text=Step%201%3A%20Download%20SAM%20local,version%20with%20the%20command%20below.&text=Step%203%3A%20Write%20your%20lambda,yaml%20on%20the%20root%20level. So the point is that if you are going to do Lambda, but you need to test locally first, this would probably be worth trying.