cljs-lambda

AWS Lambda is a service whichallows named functions to be directly invoked (via a client API), have theirexecution triggered by a variety of AWS events (S3 upload, DynamoDB activity,etc.) or to serve as HTTP endpoints (via APIGateway).

This README serves to document a Leiningenplugin(lein-cljs-lambda), template (cljs-lambda) and smalllibrary (cljs-lambda) to facilitate thewriting, deployment & invocation of Clojurescript Lambda functions.

The plugin can deploy functions itself, or theexcellent Serverless framework can be used,viaserverless-cljs-plugin.

Benefits

• Low instance warmup penalty
• Use promises, or asynchronous channels for deferred completion
• :optimizations :advanced support, for smaller zip files*
• Utilities for testing Lambda entrypoints off of EC2
• Function publishing/versioning
• Serverless integration

N.B. If using advanced compilation alongside Node's standard library,something likecljs-nodejs-externswill be required

Status

This collection of projects is used extensively in production, for importantpieces of infrastructure. While efforts are made to ensure backwardcompatibility in the Leiningen plugin, the cljs-lambda API is subject tobreaking changes.

Recent Changes

• io.nervous/lein-cljs-lambda 0.6.0 defaults the runtime of deployed functionsto nodejs4.3, unless this is overriden with :runtime in the fn-spec or onthe command-line. While your functions will be backwards compatible, your AWSCLI installation may require updating to support this change.

Coordinates

Plugin

Library

Get Started

$ lein new cljs-lambda my-lambda-project
$ cd my-lambda-project
$ lein cljs-lambda default-iam-role
$ lein cljs-lambda deploy
### 500ms delay via a promise (try also "delay-channel" and "delay-fail")
$ lein cljs-lambda invoke work-magic \
  '{"spell": "delay-promise", "msecs": 500, "magic-word": "my-lambda-project-token"}'
... {:waited 500}
### Get environment varibles
$ lein cljs-lambda invoke work-magic \
  '{"spell": "echo-env", "magic-word": "my-lambda-project-token"}'
...
$ lein cljs-lambda update-config work-magic :memory-size 256 :timeout 66

Serverless

To generate a minimal project:

$ lein new serverless-cljs my-lambda-project

Documentation

• lein-cljs-lambda plugin README / reference
• cljs-lambda library API docs

Older

• Clojurescript/Node on AWS Lambda (blog post)
• Chasing Chemtrails w/ Clojurescript (blog post)

Other

• Example project (generated from template)

Function Examples

(Using promises)

(deflambda slowly-attack [{target :name} ctx]
  (p/delay 1000 {:to target :data "This is an attack"}))

AWS Integration With eulalie

(Using core.async)

This function retrieves the name it was invoked under, then attempts to invokeitself in order to recursively compute the factorial of its input:

(deflambda fac [n {:keys [function-name] :as ctx}]
  (go
    (if (<= n 1)
      n
      (let [[tag result] (<! (lambda/request! (creds/env) function-name (dec n)))]
        (* n result)))))

See theeulalie.lambda.utildocumentation for further details.

N.B. Functions interacting with AWS will require execution under roles with theappropriate permissions, and will not execute under the placeholder IAM rolecreated by the plugin's default-iam-role task.

Further Examples

Using SNS & SQS from Clojurescript Lambda functions is covered in this workingexample,and the blogpostwhich discusses it.

Invoking

CLI

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

Programmatically

If you're interested in programmatically invoking Lambda functions fromClojure/Clojurescript, it's pretty easy witheulalie:

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

License

cljs-lambda is free and unencumbered public domain software. For moreinformation, see http://unlicense.org/ or the accompanying UNLICENSEfile.