establishing a connection to database using environment variables - mysql

Question

I'm creating an API for my app that fetches some data from my amazon db.
I have added environment variables to a custom.sh file in profile.d on my server. The weird thing is, I can print out those variables from my api, but the only variable that works when creating the connection is the user variable.
When I hard code the database credentials in the connection string it works just fine.
here is my custom.sh where I declare the environment variables
#custom environment variables, with the actual values removed
export DB_HOST=value1;
export DB_PASS=value2;
export DB_USER=value3;
export DB_NAME=value4;
here is my nodejs expressjs api file
var express = require('express');
var app = express();
var mysql = require('mysql');
var DB_HOST = formatEnvironmentVariable(process.env.DB_HOST);
var DB_USER = formatEnvironmentVariable(process.env.DB_USER);
var DB_PASS = formatEnvironmentVariable(process.env.DB_PASS);
var DB_NAME = "'"+process.env.DB_NAME+"'";
function formatEnvironmentVariable(env) {
env = "'"+env+"'";
return env
}
var pool = mysql.createPool({
host : DB_HOST,
user : DB_USER,
password : DB_PASS,
database : DB_NAME,
connectionLimit: 100,
debug: false
})
function QueryTheDatabase(req, res, querystring) {
pool.getConnection(function(err,connection){
if (err) {
connection.release();
res.json({"code" : 100, "status" : "Error in connection database"});
return;
}
console.log('connected as id ' + connection.threadId);
connection.query(querystring,function(err,rows){
connection.release();
console.log("error? "+err);
if(!err) {
res.json(rows);
}
});
connection.on('error', function(err) {
console.log("error");
res.json({"code" : 100, "status" : "Error in connection database"});
return;
});
});
}
app.get('theurl', function(req, res) {
QueryTheDatabase(req, res, "the query that works fine");
});
var server = app.listen(3000, function () {
var host = server.address().address;
var host = server.address().port;
});

Answer 1

I'm not exactly sure why only the DB_USER variable is set properly (it may be that some other process is sending that information). If you're running your shell script as such:
$ ./custom.sh
It won't work. It's essentially creating a sub-shell and the exported variables are local to that shell (they won't affect the parent)
The only way to make environment variables accessible to your node process would be to source the file first.
$ source ./custom.sh

Answer 2

I got it to work finally, turns out I didnt need to add ' ' with my format function.
instead of
var DB_HOST = formatEnvironmentVariable(process.env.DB_HOST);
var DB_USER = formatEnvironmentVariable(process.env.DB_USER);
var DB_PASS = formatEnvironmentVariable(process.env.DB_PASS);
var DB_NAME = "'"+process.env.DB_NAME+"'";
I wrote
var DB_HOST = process.env.DB_HOST;
var DB_USER = process.env.DB_USER;
var DB_PASS = process.env.DB_PASS;
var DB_NAME = process.env.DB_NAME;

Answer 3

For this I'll suggest To use
config npm
https://www.npmjs.com/package/config