DAF allows you to outsource parts of a NodeJS app to FaaS

In addition to existing tools, it supports:

• Dependencies: (install)
• Importing other files and functions (require)
• Global variables (vars)

Install

npm i -g daf # install globally

Usage

Add annotations in your Monolith code:

// l     
var a = 1;
// lend 

Run DAF via Terminal (Not recommended):

$ daf OPTIONS... 

Options:

• --fpath PATH: The path to the .js file in which you want to faasify code
• --linenum NUM: The line number of the // l ... Annotation. Beware, it's 0-indexed.
• --outpath PATH: The path where the generated FaaS functions will be put (outpath/lambdas/...).
• [--commentout]: If specified, the faasified section will be replaced with an Lambda API call. Don't forget to specify //l name(...)!

Run DAF via Editor Extension:

Upcoming: https://github.com/qngapparat/daf-vscode

Output

The tool creates an equivalent Lambda function of that section in [--output]/lambdas/[name]:

└── lambdas
    └── 28723n2398jfs9f87239uhfe9
        ├── index.js
        └── package.json 

You can deploy this function directly to AWS Lambda. One file can have multiple // l ... // lend sections, that can be converted separately.

Annotations

//l can be followed by any combination of these space-separated directives.

name

You can give your Lambda a name to better keep track of it:

// l name(mylamb)
 var a = 1
// lend

└── lambdas
    └── mylamb
       └── ....
    

vars

Your code might rely on global variables. You can denote them with vars():

var a = 1
// l vars(a)
a++
// lend

They will be added to the scope inside the Lambda.

require

Your code might rely on functions from other files. You can declare that using require():

// l require(./foo.js as foo)
foo()
// lend

A portable version of foo.js is then included in the deployment package, and it is added to the scope inside the Lambda.

└── lambdas
    └── myfunc
       └── foo.js  // <---
       └── ...

If foo in turn depends on other functions or dependencies, they are bundled as well (recursively) using webpack.

install

Your code might depend on NPM packages. You can specify them with install(). They will be included in your deployment package.

// l install(opencv2)
....
// lend

You probably want to import it as well:

// l install(opencv2) require(opencv2)
   opencv2.detectFaces(...)
// lend

return

Your monolith code may have no return statement. To receive something back from the lambda, use return()

// l return(a)  
  var a = 1
  var b = 2
// lend

Useful hints

Multiple parameters

With most // l expressions, you can provide a comma-separated list too:

// l vars(a, b, c)
...

Aliasing

You can rename functions and packages, when import them:

// l require(opencv2 as cv)
  cv.detectFaces(...)
// lend

This is obligatory if you import local functions.

Versioning

You can specify the exact versions of the NPM packages to install:

// l install(pkg1@latest, pkg2^1.0.0, pkg3>=1.2.3)
...
// lend

The syntax follows this official schema: https://docs.npmjs.com/misc/semver