How to get Parameter Store Parameters by path when using Lambda Layer?

The AWS-Parameters-and-Secrets-Lambda-Extension layer does not have the capability to retrieve SSM parameters based on a path value. Instead, it expects a name parameter in the query string, so you can retrieve only one record at a time based on the SSM parameter name.

If you want to retrieve SSM parameters based on a path value, then you can use the following NuGet package, which enables you to retrieve multiple configuration values simultaneously from the SSM parameter store.

Amazon.Extensions.Configuration.SystemsManager

The mentioned Amazon Systems Manager NuGet package utilizes the .NET ConfigurationBuilder to process the configuration values from the SSM parameter store. In order to access the ConfigurationBuilder, you also need to include the following NuGet packages in your lambda function.

Microsoft.Extensions.Configuration
Microsoft.Extensions.Options.ConfigurationExtensions

Here is a sample code snippet that shows how to retrieve configuration values from the SSM parameter store based on the path value:

public class FunctionHandler
{
    private readonly AppConfig _appConfig;
    
    public FunctionHandler()
    {
        var configurations = new ConfigurationBuilder()
            .AddSystemsManager(cs =>
            {
                cs.Path = "/service1/prod";
                cs.ReloadAfter = TimeSpan.FromMinutes(10);
            })
            .Build();
        // Define AppConfig to match your SSM path hierarchy  
        var config = configurations.Get<AppConfig>();
    }

    public string Handle(string input, ILambdaContext context)
    {
        return JsonConvert.SerializeObject(_appConfig);
    }

p.s. To retrieve configuration values by the path in your Lambda function, you should grant the following IAM role permission: ssm:GetParametersByPath