External Adapter Example

This example originated from this Medium post that explains how to set up a Go function using AWS Lambda.

This repository should serve as an example for making external adapters available for the ChainLink network. At a minimum, developers should provide basic instructions for installing the external adapter. Additional information, like what is contained in the headings listed below, will further help developers and users of the external adapter. The installation instructions below are far more verbose than necessary in order to get someone who isn't familiar with AWS Lambda set up in a way that can be followed step-by-step.

API Resource

To use this adapter, you will need to create an account with The Movie DB.

You can then get your API key by going to your Settings, then click on API (or follow that link when logged in).

Take note of the "API Key (v3 auth)" as that is what we'll use in this adapter.

Build & Package

First, clone this repository, then enter into the directory

cd ExternalAdapterExample

Build the binary

GOOS=linux go build -o bin/main src/main.go

Zip the binary

zip deployment.zip bin/main

Testing

Export the API key to the local environment variable API_KEY

export API_KEY=12345123451234512345123451234512

Then run the test command

go test ./...

Installation (AWS Lambda)

This walkthrough doesn't take any consideration to security. Setting up your AWS Lambda function this way will allow anyone to invoke the function.

The deployment.zip file can be added to AWS Lambda either through the command line, as shown below, or through the GUI.

For the command-line, run this (after change the name and role), then go to the Environment Variables step

aws lambda create-function \
 --region us-east-1 \
 --function-name ExternalAdapterExample \
 --zip-file fileb://./deployment.zip \
 --runtime go1.x \
 --role arn:aws:iam::<account-id>:role/ExternalAdapterRole \
 --handler main

For adding the deployment.zip file via the GUI, navigate to Services > Lambda and click Create function

Use the following settings, but again, change the names appropriately:

Author from scratch
Name: ExternalAdapterExample
Runtime: Go 1.x
Role: Create new role from template(s)
Role name: ExternalAdapterRole
Policy Templates: Basic Edge Lambda permissions

Click the Create function button

Once the Configuration page loads, under Function Code, change the Handler name to main and click the Upload button

Under the Environment Variables, enter API_KEY for the key, and your API key for the value.

Scroll up to the top and click the Save button. The function can now be tested within AWS Lambda. Click the Test button.

Empty the JSON out to look like it does below and click Create.

Now click the Test button again and the execution result should have succeeded.

Click API Gateway on the left-hand panel under the "Add triggers" label. Under "Configure triggers" click on the link to Amazon API Gateway console.

Click the Create API button and use the following settings, changing the Name and Description for your purpose:

New API
API Name: ExternalAdapterAPI
Description: This is an example API for AWS
Endpoint Type: Edge optimized

Click Create API and when brought to the next screen, click the Actions drop-down and choose Create Resource.

For the New Child Resource page, use the following configuration, changing the name to your choice:

Configure as proxy resource: Unchecked
Resource Name: ExternalAdapterExample
Resource Path: leave as default
Enable API Gateway CORS: Unchecked

Click Create Resource

With the /externaladapterexample path selected, click the Actions drop-down and choose Create Method.

In the drop-down that appears, choose GET and click the check button.

Configure the action with the following setting, but change the Lambda Region to your choice:

Integration type: Lambda Function
Use Lambda Proxy integration: Unchecked
Lambda Region: us-west-2
Lambda Function: ExternalAdapterExample
Use Default Timeout: Checked

Click Save and click OK on the prompt that appears for giving API Gateway permissions to invoke your Lambda function.

Finally, click the Actions drop-down again, and choose Deploy API.

For the Deploy API dialog, use the following configuration, change name if desired:

Deployment stage: [New Stage]
Stage name: adapters

Click the Deploy button and you should be brought to the Stages page.

Now you can go back to the ExternalAdapterExample function configuration (you may need to refresh), click the configured API Gateway

The ExternalAdapterAPI should already be configured with the GET method.

Expand out the information and navigate to the Invoke URL in a new tab, or you can use curl to test via the command-line.