How to read in an environment variable on Netlify using a lambda function.

forecast.js

/**
 * This was a proof of concept for me to be able to 
 * retrieve an API key using a Netlify environment variable
 * using this lambda function. I spent a lot of time looking
 * for a complete example like this--without any luck.
 *
 * So, here's a step-by-step of what I did.
 * 
 * 1) For this function to work, define the env variable in
 * Netlify > Site > Build & Deploy > Environment > Edit Variables
 * 
 * 2) Place this function in your /functions directory. Add
 * ./functions to your Site > Functions > Edit Settings
 *
 * 3) To find out how to call this, the lambda functions endpoint
 * will follow this pattern.
 *
 * https://yourapp.netlify.com/.netlify/functions/yourfunction
 *
 * 4) You can verify this in your Site > Functions tab.
 *
 * For my proof of concept, the endpoint was
 * https://myapp.netlify.com/.netlify/functions/forecast?longitude=40.7720232&latitude=-73.9732319
 *
 * 5) I invoked this endpoint in my app.js code that looked like this.
 * Notice that I hardcoded the coordinates. I just needed to know if 
 * this would work. And, it did. I stopped here once I proved it worked.
 *
 * function getForecastFromNetwork(coords) {
 *   return fetch(`/.netlify/functions/forecast?longitude=40.7720232&latitude=-73.9732319`)
 *     .then((response) => {
 *       return response.json();
 *     })
 *     .catch(() => {
 *       return null;
 *     });
 * }
 *
 * 6) I added `npm install` to my site's build command.
 */
const fetch = require('node-fetch');
/* Can do this too. See further below.
const { DARKSKY_API_KEY } = process.env;
*/

exports.handler = async (event, context) => {
  try{
    const latitude  = event.queryStringParameters.latitude;
    const longitude = event.queryStringParameters.longitude;
    
    /** 
     * This lambda (aws) function has access to Netlify build env variables. 
     * That's how process.env.DARKSKY_API_KEY can work. There's no need to
     * use dotenv or write a .env file to disk.
     */
    const response = await fetch(`https://api.darksky.net/forecast/${process.env.DARKSKY_API_KEY}/${latitude},${longitude}`);
    const data     = await response.json();
    return {
      statusCode: 200,
      body: JSON.stringify(data)
    };
  } catch (err) {
    return {
      statusCode: 500,
      body: err.toString()
    };
  }
};

Thanks for describing the process.

Hi @mdestafadilah,

Thanks for your comment. I don't have any plans on making a video out of this. I worked on this so long ago, and I've never needed to do it again. I created this gist only to document my proof of concept.

If I make a screencast of this process, I will let you know! :-)

mark

nice here come tobe true ... thanks for your process it.

Thanks for describing the process.

You're welcome @gurdeepsinghsaini :-)