Using a Middleware

The basics

To use a middleware in your lambda function, you need to add it using the function use in the constructor. For example, to add the SQSTracingMiddleware you need to follow the following steps:

1. Add the corresponding package:

   dotnet package add Voxel.MiddyNet.Tracing.SQSMiddleware
   

2. Add the corresponding using in your lambda function:

   using Voxel.MiddyNet.Tracing.SQSTracingMiddleware;
   

3. Add it to the engine in your constructor:

   public MySQSLambdaFunction()
   {
       // Your own initializations
       Use(new SQSTracingMiddleware());
   }
   

And that’s all. MiddyNet will execute this middleware before and after your function runs. In this particular case, the middleware only will do things in the before section.

Middleware configurations

Some middlewares can have configurations you might want to take advantage of. The configuration will usually be a parameter of the constructor, like in the SSM middleware:

public class MySQSLambdaFunction: MiddyNet<SQSEvent,int>
{
    private const string ClientIdName = "clientIdName";
    private const string ClientSecretName = "clientSecretName";

    public MySQSLambdaFunction()
    {
        var clientIdPath = Environment.GetEnvironmentVariable("clientIdPath");
        var clientSecretPath = Environment.GetEnvironmentVariable("clientSecretPath");

        Use(new SSMMiddleware<SNSEvent, int>(new SSMOptions
        {
            CacheExpiryInMillis = 60000,
            ParametersToGet = new List<SSMParameterToGet>
            {
                new SSMParameterToGet(ClientIdName, clientIdPath),
                new SSMParameterToGet(ClientSecretName, clientSecretPath)
            }
        }));

        Use(new SQSTracingMiddleware<SNSEvent, int>());
    }

    protected override async Task<int> Handle(SNSEvent lambdaEvent, MiddyNetContext context)
    {
        // Your business logic

        return await Task.FromResult(0);
    }
}