Chainlink NodeJS External Adapter Template

This template provides a basic framework for developing Chainlink external adapters in NodeJS. Comments are included to assist with development and testing of the external adapter. Once the API-specific values (like query parameters and API key authentication) have been added to the adapter, it is very easy to add some tests to verify that the data will be correctly formatted when returned to the Chainlink node. There is no need to use any additional frameworks or to run a Chainlink node in order to test the adapter.

Creating your own adapter from this template

Clone this repo and change "ExternalAdapterProject" below to the name of your project

git clone https://github.com/thodges-gh/CL-EA-NodeJS-Template.git ExternalAdapterProject

Enter into the newly-created directory

cd ExternalAdapterProject

You can remove the existing git history by running:

rm -rf .git

See Install Locally for a quickstart

Input Params

• base, from, or coin: The symbol of the currency to query
• quote, to, or market: The symbol of the currency to convert to

Output

{
 "jobRunID": "278c97ffadb54a5bbb93cfec5f7b5503",
 "data": {
  "USD": 164.02,
  "result": 164.02
 },
 "statusCode": 200
}

Install Locally

Install dependencies:

yarn

Test

Run the local tests:

yarn test

Natively run the application (defaults to port 8080):

Run

yarn start

Call the external adapter/API server

curl -X POST -H "content-type:application/json" "http://localhost:8080/" --data '{ "id": 0, "data": { "from": "ETH", "to": "USD" } }'

Docker

If you wish to use Docker to run the adapter, you can build the image by running the following command:

docker build . -t external-adapter

Then run it with:

docker run -p 8080:8080 -it external-adapter:latest

Serverless hosts

After installing locally:

Create the zip

zip -r external-adapter.zip .

Install to AWS Lambda

• In Lambda Functions, create function
• On the Create function page:
  • Give the function a name
  • Use Node.js 12.x for the runtime
  • Choose an existing role or create a new one
  • Click Create Function
• Under Function code, select "Upload a .zip file" from the Code entry type drop-down
• Click Upload and select the external-adapter.zip file
• Handler:
  • index.handler for REST API Gateways
  • index.handlerv2 for HTTP API Gateways
• Add the environment variable (repeat for all environment variables):
  • Key: API_KEY
  • Value: Your_API_key
• Save

To Set Up an API Gateway (HTTP API)

If using a HTTP API Gateway, Lambda's built-in Test will fail, but you will be able to externally call the function successfully.

• Click Add Trigger
• Select API Gateway in Trigger configuration
• Under API, click Create an API
• Choose HTTP API
• Select the security for the API
• Click Add

To Set Up an API Gateway (REST API)

If using a REST API Gateway, you will need to disable the Lambda proxy integration for Lambda-based adapter to function.

• Click Add Trigger
• Select API Gateway in Trigger configuration
• Under API, click Create an API
• Choose REST API
• Select the security for the API
• Click Add
• Click the API Gateway trigger
• Click the name of the trigger (this is a link, a new window opens)
• Click Integration Request
• Uncheck Use Lamba Proxy integration
• Click OK on the two dialogs
• Return to your function
• Remove the API Gateway and Save
• Click Add Trigger and use the same API Gateway
• Select the deployment stage and security
• Click Add

Install to GCP

• In Functions, create a new function, choose to ZIP upload
• Click Browse and select the external-adapter.zip file
• Select a Storage Bucket to keep the zip in
• Function to execute: gcpservice
• Click More, Add variable (repeat for all environment variables)
  • NAME: API_KEY
  • VALUE: Your_API_key