How to set credentials on AWS SDK on NET Core?

Maybe this is too late for you but if you are using docker or have some other environment/setup where it's not possible/easy to use AWS profiles then you can still use environment vars. Eg:

var awsOptions = Configuration.GetAWSOptions();
awsOptions.Credentials = new EnvironmentVariablesAWSCredentials();
services.AddDefaultAWSOptions(awsOptions);
services.AddAWSService<IAmazonS3>();

Then set AWS_ACCESS_KEY_ID & AWS_SECRET_ACCESS_KEY & AWS_REGION in your environment.

It seems that Amazon have made this harder to find in the docs than it needs to be.

Running in AWS for reals is ok because you should be using a role but if your using docker for dev then setting up a profile in the container is a PITA.

AWS SDK for .NET uses following order to load credentials:

1. AWSOptions.Credentials property

AWSOptions awsOptions = new AWSOptions
{
    Credentials = new BasicAWSCredentials("yourAccessKey", "yourAccessSecret")
};
builder.Services.AddDefaultAWSOptions(awsOptions);

2. AWSOptions.Profile property

AWSOptions awsOptions = new AWSOptions
{
    Profile = "custom",
    ProfilesLocation = @"c:\temp\credentials"
};
builder.Services.AddDefaultAWSOptions(awsOptions);

If the profile location is not specified, it will look at the default location C:\Users\.aws\credentials.

3. Credential Profile Store Chain

If both AWSOptions.Credentials and AWSOptions.Profile are not supplied or AWSOptions object itself is null. In this case, credential profile name will be loaded from the environment variable AWS_PROFILE.

• Profile Name: If there is no such AWS_PROFILE environment variable, then default will be used as a profile name.
• Profile Location: C:\Users\.aws\credentials

4. Environment Variables AWS Credentials

If SDK still hasn't got the credentials, then it checks for the following environment variables to load the AWS credentials.

ENVIRONMENT_VARIABLE_ACCESSKEY = "AWS_ACCESS_KEY_ID";     
ENVIRONMENT_VARIABLE_SECRETKEY = "AWS_SECRET_ACCESS_KEY";        
ENVIRONMENT_VARIABLE_SESSION_TOKEN = "AWS_SESSION_TOKEN";

5. EC2 Instance Profile / ECS Task Profile

Finally, this is the most important place where the SDK looks for the credentials. This would be the best place for the applications that are running in the AWS environment. In this case, SDK loads the AWS credentials from the EC2 instance profile or ECS task role.

I have also written a blog on the same topic, you can checkout that from here - Understanding Credential Loading in AWS SDK for .NET

This helps to avoid getting credentials from environment using the appsettings for development purpose

var awsOption = Configuration.GetAWSOptions();
    awsOption.Credentials = new BasicAWSCredentials(Configuration["AWS:AccessKey"], Configuration["AWS:SecretKey"]);
    services.AddDefaultAWSOptions(awsOption);

Same documentation also includes a section for setting up the credentials. Check it out here http://docs.aws.amazon.com/sdk-for-net/v3/developer-guide/net-dg-config-creds.html

It doesn't give an example of setting up the credentials using the appSettings.json file because they don't think it's the right (secure) way to do it.

Here is from the introduction part of the section about setting up the credentials:

Don't put literal access keys in your application, including the project's App.config or Web.config file. If you do, you create a risk of accidentally exposing your credentials if, for example, you upload the project to a public repository.