Better doc. Custom error message from keys.js.

Dockerfile

@@ -1,6 +1,7 @@
 FROM node:10
 
 COPY . /app
+COPY /etc/keys.js /app/keys.js
 WORKDIR /app
 RUN yarn install
 

README.md

@@ -13,6 +13,9 @@ Inspired by:
 
 ## API usage
 
+!!! This fork REQUIRE an api key for each request with a parameter ?key=APIKEYGOESHERE
+Rename existing keys_example.js file, place it in your /etc/keys.js and store properly hashed (sha256 hex format) keys inside the file !!!
+
 The service has a very simple API. Just post your latitude-longitude pairs as a JSON array to the service and receive an array of elevations as response. Maximum post payload is by default 700 KB (which fits roughly 10,000 points).
 
 ```bash

index.js

@@ -31,13 +31,13 @@ async function handlePOST(req, res) {
 
   if (!apiKey) {
     return send(res, 400, {
-      error: apiMessage('Missing'),
+      error: keys.message('Missing'),
     }); 
   }
 
   if (verifyKey(apiKey) < 0) {
     return send(res, 400, {
-      error: apiMessage('Invalid'),
+      error: keys.message('Invalid'),
     }); 
   }
 
@@ -65,13 +65,13 @@ async function handleGET(req, res) {
   const apiKey = reqQuery.key;
   if (!apiKey) {
     return send(res, 400, {
-      error: apiMessage('Missing'),
+      error: keys.message('Missing'),
     }); 
   }
 
   if (verifyKey(apiKey) < 0) {
     return send(res, 400, {
-      error: apiMessage('Invalid'),
+      error: keys.message('Invalid'),
     }); 
   }
 
@@ -115,16 +115,13 @@ async function handler(req, res) {
   }
 }
 
+// This function verify if the hash of the api key passed by the user
+// request matches a key stored inside keys.js file
 function verifyKey(key) {
   const shasum = crypto.createHash('sha256');
   shasum.update(key);
   const digest = shasum.digest('hex');
   return allKeys.indexOf(digest);
 }
 
-function apiMessage(wrong) {
-  return wrong + ' API key. Please email Téo or Julien at [email protected] or [email protected].'
-}
-
-
 module.exports = cors(handler);

keys_example.js

@@ -0,0 +1,12 @@
+// This file should be renamed as keys.js
+// It is aimed to store an array of hashed keys to be compared against the hashed api key
+// received from the user request.
+// A custom message can be returned in case of 'Missing' or 'Invalid' api key.
+module.exports = {
+	get : function() {
+		return ['first-hashed-key-goes-here', 'second-hashed-key-goes-here'];
+	},
+	message : function(wrong) {
+  		return wrong + ' API key. Custom message... Wrong is either invalid or missing';
+	},
+}