AWS .NET Configuration Extension for Systems Manager

Amazon.Extensions.Configuration.SystemsManager simplifies using AWS SSM's Parameter Store as a source for configuration information for .NET Core applications. This project was contributed by @KenHundley.

The library introduces the following dependencies:

• AWSSDK.Extensions.NETCore.Setup
• AWSSDK.SimpleSystemsManagement
• Microsoft.Extensions.Configuration

Getting Started

Follow the examples below to see how the library can be integrated into your application. This extension adheres to the same practices and conventions of Configuration in ASP.NET Core.

ASP.NET Core Example

The most common use case for this library is to pull configuration from Parameter Store. You can easily add this functionality by adding 1 line of code:

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration(builder =>
            {
                builder.AddSystemsManager("/my-application/");
            })
            .UseStartup<Startup>();
}

HostBuilder Example

Microsoft introduced .NET Generic Host to de-couple HTTP pipeline from the Web Host API. The Generic Host library allows you to write non-HTTP services using configuration, dependency injection, and logging features. The sample code below shows you how to use the the AWS .NET Configuration Extension library:

namespace HostBuilderExample
{
    public static async Task Main(string[] args)
    {
        var host = new HostBuilder()
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                config.AddSystemsManager("/my-application/");
            })
            .ConfigureServices((sc) => { ... })
            .Build();

        await host.RunAsync();
    }
}

Samples

Custom ParameterProcessor Sample

Example of using a custom IParameterProcessor which provides a way to store and retreive null values. Since AWS Parameter Store params are string literals, there is no way to store a null value by default.

namespace CustomParameterProcessorExample
{
    public class CustomParameterProcessor : DefaultParameterProcessor
    {
        const string NULL_STRING_LITERAL = "NULL";
        
        public override string GetValue(Parameter parameter, string path)
        {
            string value = base.GetValue(parameter, path);
            return value == NULL_STRING_LITERAL ? null : value;
        }
    }
    
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration(builder =>
                {
                    builder.AddSystemsManager(config => {
                        config.Path = "/my-application/";
                        config.ParameterProcessor = new CustomParameterProcessor();
                    });
                })
                .UseStartup<Startup>();
    }
}

For more complete examples, take a look at sample projects available in samples directory.

Reloading in AWS Lambda

The reloadAfter parameter on AddSystemsManager() enables automatic reloading of configuration data from Parameter Store as a background task.

In AWS Lambda, background tasks are paused after processing a Lambda event. This could disrupt the provider from retrieving the latest configuration data from Parameter Store. To ensure the reload is performed within a Lambda event, we recommend calling the extension method WaitForSystemsManagerReloadToComplete from the IConfiguration object in your Lambda function. This method will immediately return unless a reload is currently being performed. The WaitForSystemsManagerReloadToComplete extension method to IConfiguration is available when you add the a using Amazon.Extensions.Configuration.SystemsManager statement. See the example below:

using Amazon.Extensions.Configuration.SystemsManager

...

var configurationBuilder = new ConfigurationBuilder();
configurationBuilder.AddSystemsManager(IntegTestFixture.ParameterPrefix, fixture.AWSOptions);
var configurations = configurationBuilder.Build();

...

configurations.WaitForSystemsManagerReloadToComplete(TimeSpan.FromSeconds(5));

Getting Help

We use the GitHub issues for tracking bugs and feature requests and have limited bandwidth to address them.

If you think you may have found a bug, please open an issue

Contributing

We welcome community contributions and pull requests. See CONTRIBUTING.md for information on how to set up a development environment and submit code.

Additional Resources

AWS .NET GitHub Home Page
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License

Libraries in this repository are licensed under the Apache 2.0 License.

See LICENSE and NOTICE for more information.