This post is an ported, edited version of the original
Purpose
This post shows you how to run PureScript 0.12 on AWS Lambda, using Express on the Serverless platform.
Setup
The final output of this article is also a repo
Prerequisites.
You should have nodejs (i.e. nvm, npm) setup on your machine, preferably 8.10. AWS Lambda uses 8.10. I’m new to nodejs land but I’m guessing that higher minor versions should be ok.
Software Setup
npm install -g purescript
npm install -g pulp bower
npm install -g serverless
AWS Credentials
If you haven’t already, generate an AWS key and secret. This user must have AdministratorAccess permissions. Here are the docs or a slightly outdated video. For the video, follow on to 1:40 and ignore the Serverless Dashboard instructions(around 0:58 to 1:00), we are going to do that on the command line.
serverless config credentials --provider aws --key your-aws-key --secret your-aws-secret
Project Setup
mkdir hello-purescript-serverless
cd hello-purescript-serverless
npm init # fill in as directed
pulp init
pulp build
If all goes well, you should see something like below:
* Building project in /Users/rabraham/Documents/dev/purescript/hello-purescript-serverless
Compiling Data.Symbol
Compiling Type.Data.RowList
...
Compiling Main
Compiling PSCI.Support
Compiling Effect.Class.Console
* Build successful.
Now let’s install our project specific packages.
bower install --save purescript-aws-lambda-express purescript-express
npm install --save aws-serverless-express express
npm install serverless-offline --save-dev
purescript-express is a wrapper on express while purescript-aws-lambda-express provides the wrapper for AWS Lambda. serverless-offline allows us to test the code locally before deploying it to AWS Lambda.
At time of writing, purescript-express has an issue where we have to install the following two packages too. Try a pulp build right now and if that fails, run the following commands
bower install --save purescript-test-unit
bower install --save purescript-aff
Let’s build it
pulp build
You should see some warnings but at the end, you should see * Build successful.
Main Course
In your src/Main.purs, delete the previous code and paste the following:
module Main where
import Node.Express.App (App, get)
import Node.Express.Handler (Handler)
import Node.Express.Response (sendJson)
import Network.AWS.Lambda.Express as Lambda
-- Define an Express web app
indexHandler :: Handler
indexHandler = do
sendJson { status: "ok" }
app :: App
app = do
get "/" indexHandler
-- Define the AWS Lambda handler
handler :: Lambda.HttpHandler
handler =
Lambda.makeHandler app
Build Your App
pulp build
Serverless Setup
In the root of your project, create the file serverless.yml and paste the following:
service: purescript-aws-lambda-express-test
provider:
name: aws
runtime: nodejs8.10
memorySize: 128
# stage: ${opt:stage dev}
region: us-east-1
functions:
lambda:
handler: output/Main/index.handler
events:
- http:
path: / # this matches the base path
method: ANY
- http:
path: /{any+}
method: ANY
plugins:
- serverless-offline
Let’s test this locally: On one terminal.
serverless offline start
Open another terminal and do:
curl http://localhost:3000
You should see {"status":"ok"}
Deploy
Once it works locally, let’s deploy to AWS.
serverless deploy -v
Output should look like something below. Note, your endpoint will be different:
Serverless: Packaging service
...
Service Information
service: purescript-aws-lambda-express-test
stage: dev
region: us-east-1
...
Stack Outputs
...
ServiceEndpoint: https://l4qajv7v95.execute-api.us-east-1.amazonaws.com/dev
....
Copy the link shown as ServiceEndpoint and you know what to do!
curl https://l4qajv7v95.execute-api.us-east-1.amazonaws.com/dev
Output:
{"status":"ok"}%
Undeploy
serverless remove -v
I hope this enables you to make PureScript web applications! Thanks to purescript-express and purescript-aws-lambda-express for making this possible.
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