A simple example of implementing AWS lambda like functionality with Node.js and Docker containers.

Build the lambda daemon image using:

cd daemon
docker build -t lambda .

Then, from a different location, you can create your own lambda functions,

lambda.js

exports.handler = function(input, context) {
  context.succeed({abc:123});
};

Dockerfile

FROM lambda
COPY lambda.js /usr/src/app/lambda/
EXPOSE 8080

docker build -t lambda-example .

To run:

docker run -p=8080:8080 lambda-example

• Your lambda function will be running at http://{dockerhost}:8080/
• Your lambda function accepts JSON or url-encoded form input.
• Your lambda function can provide a Passport Authentication Strategy.
• You can do a HTTP GET to http://{dockerhost}:8080/info to view basic statistics.

Program model

The context object has the following methods:

• succeed(body) - call to indicate that the function is complete and successful. The body will be passed to JSON.stringify and returned.
• fail(error) - call to indicate that the function has failed. The error will be passed to JSON.stringify and returned. If the error object has a status property, it will be set as the HTTP Response status code (e.g. error.status = 400)
• cancel() - call to indicate that the function has been aborted/canceled. An empty response will be returned
• done(error,body) - alternative to succeed and fail that uses the typical Node.js callback pattern.
• getRemainingTimeInMillis() - returns the approximate remaining time before the function times out. The default timeout is 10 seconds (which means the function will be automatically aborted if it does not return a result within 10 seconds). The default can be overriden using the LAMBDA_TIMEOUT environment variable.

The context object has the following properties:

• id - unique UUID for the request
• ts - Unix timestamp indicating when the request was receieved
• ip - The client IP address
• name - The name of the lambda function. The name can be set using the LAMBDA_NAME environment variable
• lenient - true if the lambda function should be run in lenient mode. Defaults to false. This is requested by the client using the HTTP Prefer header (Prefer: handling=lenient) in the request. Lenient mode would indicate that the function should be more tolerant of possible failure conditions.

(note, these properties are different than what you see in Amazon's API. The intent here was to provide an example of similar functionality, not to fully duplicate it)

Lambda functions must be written to be as ephemeral as possible, maintaining no state of their own. Each invocation should be entirely self-contained.

Your lambda functions can require other modules but those need to be installed using the Dockerfile. A future iteration of this demo may try to automate the installation process a bit more for lambda function dependencies.