lambdahttp

Do you yearn for the days of listening on port 80(80) for web traffic? Does this new serverless world scare you and make you wonder if you'll have to refactor your existing code? Or maybe you have a crusty old binary lying around, have lost the source code and are desperate to make it work on AWS Lambda?

If so, lambdahttp is for you.

How do I use it?

• Grab the latest zip from the Releases tab on GitHub.
• Add your app to the zip file.
• Upload the zip to S3.
• Create a Lambda function from that zip file. Configure it to use the provided runtime and specify a shell command as the "handler", e.g. ./myprogram listen --port 8080.
• Do the API Gateway / Application Load Balancer dance.
• Swim in the savings of serverless.

If you app doesn't listen on port 8080, you can specify a different one using the PORT environment variable.

Additionally, lambdahttp has no real way of knowing when your app is ready to start serving traffic. For this reason, it will continuously make requests to /ping until that endpoint returns a 200 OK - this is how it knows you are good to go. If that path doesn't work for you, specify a different one in the HEALTHCHECK_PATH environment variable.

How does it work?

Let me explain through the only kind of diagram I know: a sequence diagram.

lambdahttp communicates with the Lambda service using the Lambda runtime interface and converts these requests into regular HTTP over TCP. It converts the responses back to the format expected by Lambda and voilà. Nothing new you need to learn.

What bonus functionality exists?

Glad you asked. Since Lambda doesn't have the same level of support for Secrets Manager and Parameter Store that ECS has, lambdahttp fills in the gaps. If you set an environment variable named EXAMPLE to value {aws-ssm}/path/to/param, then lambdahttp will retrieve the value at /path/to/param and populate EXAMPLE with that value.

Likewise, EXAMPLE={aws-sm}secretNameOrArn will cause lambdahttp to replace the value with the JSON secret in secretNameOrArn. lambdahttp also recognises {aws-sm}secretNameOrArn::password syntax, in which case it will retrieve the secret and populate EXAMPLE with only the value in the password key.