Using AmazonSimpleSystemsManagementClient GetParameters fails

Question

I have a Lambda in C# and I'm trying to access parameters stored in the ECQ Parameter Store. The parameters are stored as a String Value.

My Lambda is configured to use an existing role. In IAM, I've assigned the following policies to the role:

• AmazonRedshiftReadOnlyAccess
• AmazonKinesisReadOnlyAccess
• AmazonVPCFullAccess
• AWSLambdaExecute
• AmazonSSMReadOnlyAccess
• AWSLambdaVPCAccessExecutionRole

The Lambda runs inside of our VPC and if the parameter value is hard-coded it executes successfully.

My code to get the parameter is:

var client = new AmazonSimpleSystemsManagementClient(RegionEndpoint.APSoutheast2);
var request = new GetParametersRequest
{
   Names = new List<string>{ "ParameterName" }
};
var response = client.GetParametersAsync(request).Result;
var value = response.Parameters.Single().Value;

I have logging before and after the call to GetParametersAsync and it doesn't get to the logging after the call.

What do I need to do to be able to get the parameter value from the Lambda?

Answer 1

The issue was caused by the Lambda running inside of our VPC. Accessing SSM is done via the internet so I had to configure a NAT Gateway to give the Lambda access to the internet.

Once this was done, the Lambda could access the SSM parameters successfully.

Answer 2

You should have something similar to:

public async Task<Response> ProcessS3ImageResizeAsync(SimpleS3Event input)
{
   var response = await client.DoAsyncWork(input);
   return response;
}

In async call the response is not immediate, thus you need to wait before.

More information:

[1] http://docs.aws.amazon.com/lambda/latest/dg/dotnet-programming-model-handler-types.html#dot-net-async