Understanding Heroku bcrypt errors in log when deploying Nodejs app - node.js

Question

I am trying to deploy my node.js app to Heroku. It works perfectly fine locally, but when I try to deploy it I keep getting this:
2017-12-12T17:32:18.220591+00:00 app[web.1]: > ev#1.0.0 start /app
2017-12-12T17:32:18.220592+00:00 app[web.1]: > node app.js
2017-12-12T17:32:18.220592+00:00 app[web.1]:
2017-12-12T17:32:18.898850+00:00 heroku[web.1]: Process exited with status 1
2017-12-12T17:32:18.910740+00:00 heroku[web.1]: State changed from starting to crashed
2017-12-12T17:32:18.819322+00:00 app[web.1]: module.js:664
2017-12-12T17:32:18.819338+00:00 app[web.1]: return process.dlopen(module, path._makeLong(filename));
2017-12-12T17:32:18.819339+00:00 app[web.1]: ^
2017-12-12T17:32:18.819339+00:00 app[web.1]:
2017-12-12T17:32:18.819340+00:00 app[web.1]: Error: /app/node_modules/bcrypt/lib/binding/bcrypt_lib.node: invalid ELF header
2017-12-12T17:32:18.819341+00:00 app[web.1]: at Object.Module._extensions..node (module.js:664:18)
2017-12-12T17:32:18.819342+00:00 app[web.1]: at Module.load (module.js:554:32)
2017-12-12T17:32:18.819342+00:00 app[web.1]: at tryModuleLoad (module.js:497:12)
2017-12-12T17:32:18.819343+00:00 app[web.1]: at Function.Module._load (module.js:489:3)
2017-12-12T17:32:18.819343+00:00 app[web.1]: at Module.require (module.js:579:17)
2017-12-12T17:32:18.819344+00:00 app[web.1]: at require (internal/module.js:11:18)
2017-12-12T17:32:18.819344+00:00 app[web.1]: at Object.<anonymous> (/app/node_modules/bcrypt/bcrypt.js:6:16)
2017-12-12T17:32:18.819345+00:00 app[web.1]: at Module._compile (module.js:635:30)
2017-12-12T17:32:18.819345+00:00 app[web.1]: at Object.Module._extensions..js (module.js:646:10)
2017-12-12T17:32:18.819345+00:00 app[web.1]: at Module.load (module.js:554:32)
2017-12-12T17:32:18.819346+00:00 app[web.1]: at tryModuleLoad (module.js:497:12)
2017-12-12T17:32:18.819346+00:00 app[web.1]: at Function.Module._load (module.js:489:3)
2017-12-12T17:32:18.819346+00:00 app[web.1]: at Module.require (module.js:579:17)
2017-12-12T17:32:18.819347+00:00 app[web.1]: at require (internal/module.js:11:18)
2017-12-12T17:32:18.819347+00:00 app[web.1]: at Object.<anonymous> (/app/models/users.js:3:14)
2017-12-12T17:32:18.819347+00:00 app[web.1]: at Module._compile (module.js:635:30)
2017-12-12T17:32:18.827094+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2017-12-12T17:32:18.827465+00:00 app[web.1]: npm ERR! errno 1
2017-12-12T17:32:18.828807+00:00 app[web.1]: npm ERR! ev#1.0.0 start: `node app.js`
2017-12-12T17:32:18.828992+00:00 app[web.1]: npm ERR! Exit status 1
2017-12-12T17:32:18.829148+00:00 app[web.1]: npm ERR!
2017-12-12T17:32:18.829260+00:00 app[web.1]: npm ERR! Failed at the ev#1.0.0 start script.
2017-12-12T17:32:18.829357+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2017-12-12T17:32:18.834511+00:00 app[web.1]:
2017-12-12T17:32:18.834634+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2017-12-12T17:32:18.834782+00:00 app[web.1]: npm ERR! /app/.npm/_logs/2017-12-12T17_32_18_830Z-debug.log
I have done npm install and npm install bcrypt again but the error persists. From my understanding of the log I think it is clear the error relates to bcrypt?
Here is my package.json file:
{
"name": "ev",
"version": "1.0.0",
"description": "search",
"main": "app.js",
"scripts": {
"start": "node app.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
"dependencies": {
"bcrypt": "^1.0.3",
"body-parser": "*",
"express": "*",
"jsonwebtoken": "^8.1.0",
"mongoose": "*"
},
"author": "My Name",
"license": "ISC"

Answer 1

You can use a pure JS version of bcrypt library.
Something like this
https://github.com/dcodeIO/bcrypt.js
This doesnt have any native dependency and should work perfectly.
We faced a lot difficulties in deploying apps with native dependencies to heroku and other cloud platform and we had to swap some of the libraries like bcrypt with pure js versions.