Aws-sdk-net: Support setting region with Environment variables

[imkheong]

Problem:
To use .NET Core AWS SDK on Linux and Docker, I want to set the Region using environement variable instead of relying on credential file.

Expected:
When Region is not set in AWSOptions, it will fall back to use 'AWS_REGION' environment variable to set the region.

Actual:
Amazon.Extensions.NETCore.Setup.ClientFactory.CreateClient would throw an exception "Amazon.Runtime.AmazonClientException: No RegionEndpoint or ServiceURL configured.".

Steps to reproduce:

1. Remove Region property from appsettings.json.
2. Initiate any of the service client, e.g. AwsEcsService using default constructor.

Source of problem:

1. ClientFactory.cs Line 158
   config.RegionEndpoint = options.Region;
   This effectively sets RegionEndpoint to null, at the same time, ClientConfig.cs's probeForRegionEndpoint is set to false, which disables probing from environment variable.

Workaround:

1. Create AWSOptions object manually (do not use the one in appsettings). Read the Region environment variable and set it to RegionEndpoint.

var region = Environment.GetEnvironmentVariable(EnvironmentVariableAWSRegion.ENVIRONMENT_VARIABLE_REGION);
if (string.IsNullOrEmpty(region))
    throw new ArgumentNullException($"Cannot read '{EnvironmentVariableAWSRegion.ENVIRONMENT_VARIABLE_REGION}' from environment variable.", nameof(region));
services.AddDefaultAWSOptions(new AWSOptions
{
    Region = RegionEndpoint.GetBySystemName(region)
});

Suggestion:
It will be nice to simply set new AWSOptions() without having to read it manually from environment variable like

services.AddDefaultAWSOptions(new AWSOptions());

[normj]

Thanks for letting us know about the issue. I just pushed version 3.3.0.2 of AWSSDK.Extensions.NETCore.Setup that fixes the issue so that clients can pick up the region by the environment variable.

[tonholis]

Hi,

I'm still getting the exception below when my class tries to resolve the service IAmazonRekognition via DI.

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Amazon.Runtime.AmazonClientException: No RegionEndpoint or ServiceURL configured
   at Amazon.Runtime.ClientConfig.Validate() in D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Core\Amazon.Runtime\ClientConfig.cs:line 472
   at Amazon.Runtime.AmazonServiceClient..ctor(AWSCredentials credentials, ClientConfig config) in D:\JenkinsWorkspaces\trebuchet-stage-release\AWSDotNetPublic\sdk\src\Core\Amazon.Runtime\AmazonServiceClient.cs:line 154
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Amazon.Extensions.NETCore.Setup.ClientFactory.CreateClient(Type serviceInterfaceType, AWSCredentials credentials, ClientConfig config) in E:\JenkinsWorkspaces\v3-trebuchet-release\AWSDotNetPublic\extensions\src\AWSSDK.Extensions.NETCore.Setup\ClientFactory.cs:line 103
   at Amazon.Extensions.NETCore.Setup.ClientFactory.CreateServiceClient(ILogger logger, Type serviceInterfaceType, AWSOptions options) in E:\JenkinsWorkspaces\v3-trebuchet-release\AWSDotNetPublic\extensions\src\AWSSDK.Extensions.NETCore.Setup\ClientFactory.cs:line 90

I'm using the following nuget packages:

• AWSSDK.Rekognition 3.3.15.6
• AWSSDK.Extensions.NETCore.Setup 3.3.6

I also have set the environment variables as stated in the docs:

• AWS_DEFAULT_REGION
• AWS_ACCESS_KEY_ID
• AWS_SECRET_ACCESS_KEY

The @imkheong 's workaround is working ;)

[corin123]

Also ran into this issue recently. I was able to fix it by setting the AWS_REGION along with AWS_DEFAULT_REGION environment variable as well.