cljs-lambda

A Lein plugin, template and small Clojurescript library for exposing functions via AWS Lambda.

• Low instance warmup penalty
• Specify execution roles and resource limits in project definition
• Use core.async for deferred completion
• Smaller zip files with :optimizations :advanced support
• Blog post/tutorial

Examples

Get Started

$ lein new cljs-lambda my-lambda-project
$ cd my-lambda-project
$ lein cljs-lambda default-iam-role
$ lein cljs-lambda deploy
$ lein cljs-lambda invoke work-magic '{"variety": "black"}'

The above requires a recent Node runtime, and a properly-configured (aws configure) AWS CLI installation >= 1.7.31. Please run pip install --upgrade awscli if you're using an older version (aws --version).

Or, put:

In your Clojurescript project's :plugins vector.

A Simple Function

(ns cljs-lambda-example.cat
  (:require [cljs-lambda.util :refer [async-lambda-fn]]))

(def ^:export meow
  (async-lambda-fn
   (fn [{meow-target :name} context]
     (go
       (<! (async/timeout 1000))
       {:from "the-cat"
        :to meow-target
        :message "I'm  meowing at you"}))))

And its associated project.clj

The Plugin

project.clj Excerpt

See the example project:

{:cljs-lambda
 {:cljs-build-id "cljs-lambda-example"
  :aws-profile "XYZ"
  :defaults
  {:role    "arn:aws:iam::151963828411:role/lambda_basic_execution"}
  :functions
  [{:name   "dog-bark"
    :invoke cljs-lambda-example.dog/bark}
   {:name   "cat-meow"
    :invoke cljs-lambda-example.cat/meow}]}}

If :aws-profile is present, the value will be passed as --profile to all invocations of the AWS CLI, otherwise the CLI's default profile will be used.

Function Configuration

The following keys are valid for entries in [:cljs-lambda :functions]. The optional keys are listed at the end, alongside their defaults:

{:name "the-lambda-function-name"
 :invoke my-cljs-namespace.module/fn
 :role "arn:..."
 [:description "I don't think this field sees much action"
  :create true
  :timeout 3 ;; seconds
  :memory-size 128]} ;; MB

Values in [:cljs-lambda :defaults] will be merged into each function map. These values are written to Lambda on deploy. Alternatively:

$ lein cljs-lambda update-config

Will update the remote (Lambda) configuration of all of the functions listed in the project file. The :create key, defaulting to true, determines whether a create-function Lambda command will be issued if an attempt is made to deploy a not-yet-existing Lambda function.

cljsbuild

The plugin depends on cljsbuild, and assumes there is a :cljsbuild section in your project.clj. A deployment or build via cljs-lambda invokes cljsbuild - it'll run either the first build in the :builds vector, or the one identified by [:cljs-lambda :cljs-build-id].

• Source map support will be enabled if the :source-map key of the active build is true.
• If :optimizations is set to :advanced on the active build, the zip output will be structured accordingly (i.e. it'll only contain index.js and the single compiler output file).
• With :advanced, *main-cli-fn* is required to be set (i.e. (set! *main-cli-fn* identity))

Limitations

• deploy means "deploy all functions in this project". It could be changed pretty easily.
• I guess we ought to use the docstring for :description, if none is supplied.
• PR's welcome.

The Library

It's pretty tiny - please see the example project, or the project generated by lein new cljs-lambda.

Invoking

CLI

$ lein cljs-lambda invoke my-lambda-fn '{"arg1": "value" ...}'

Programmatically

If you're interested in programmatically invoking Lambda functions from Clojure/Clojurescript, it's pretty easy with eulalie:

(eulalie.lambda.util/invoke!
 {:access-key ... :secret-key ... [:token :region etc.]}
 "my-lambda-fn"
 :request-response
 {:arg1 "value" :arg2 ["value"]})

License

cljs-lambda is free and unencumbered public domain software. For more information, see http://unlicense.org/ or the accompanying UNLICENSE file.