Previously, we have simply deployed the web application under development on Heroku. Now our application will use the MongoDB database. How can we deploy a MongoDB connection in the cloud?

Further, our ultimate goal is to connect different databases in production and development environments. This article will describe the whole process.

Register MongoLab Account

We will use MongoLab here. First of all, we need to register our account. See the relevant documents. Here

Create a new database

After landing, follow these steps

Select single node, sandbox. Note that only a specific area has a single node to choose from. You need to try which one is feasible manually.

Create successful results

If you don't succeed in creating it, most of it is database name conflict. Just try a few more.

Click Name to enter the database, prompt to create a user to use the database, then we switch to the Users tab, click add database user

Configure Mongolab database connection string to heroku configuration file

$ heroku config:set MONGOLAB_URI=mongodb://<dbuser>:<dbpassword>@ds127958.mlab.com:27958/congyh
Setting MONGOLAB_URI and restarting ⬢ sheltered-everglades-85543... done, v10
...

Synchronize test data from local development database to Mongolab

$ mkdir -p ~/tmp/mongodump

$ mongodump -h localhost:27017 -d Loc8r -o ~/tmp/mongodump

$ mongorestore -h ds127958.mlab.com:27958 -d congyh -u <username> -p <password> ~/tmp/mongodump/Loc8r
...
2016-12-11T12:40:06.685+0800    finished restoring congyh.locations (3 documents)
2016-12-11T12:40:06.685+0800    done

First connect to the remote database using the mongo shell

$ mongo ds127958.mlab.com:27958/congyh -u <username> -p <password>
MongoDB shell version v3.4.0
connecting to: mongodb://ds127958.mlab.com:27958/congyh
MongoDB server version: 3.2.11
WARNING: shell and server versions do not match
rs-ds127958:PRIMARY>

List data

> show collections
> db.locations.find()

Allow applications to automatically select connected databases based on their environment

After the above operations, we have obtained a cloud database synchronized with the local development database. Because our application is developed locally and deployed Heroku at the same time, it is necessary to connect the application to the correct database automatically according to the environment.

First, you need to switch the application deployed on heroku to the production environment (note: to execute instructions in the application root directory).

$ heroku config:set NODE_ENV=production
Setting NODE_ENV and restarting ⬢ sheltered-everglades-85543... done, v11
NODE_ENV: production

var dbURI = 'mongodb://localhost/Loc8r';
if (process.env.NODE_ENV === 'production') {
    dbURI = process.env.MONGOLAB_URI;
}
mongoose.connect(dbURI);

First test connecting to the local development database

$ nodemon
Mongoose connected to mongodb://localhost/Loc8r

Then test connecting to the Mongolab database

$  NODE_ENV=production MONGOLAB_URI=mongodb://<dbuser>:<dbpassword>@ds127958.mlab.com:27958/congyh nodemon
Mongoose connected to mongodb:///<dbuser>:<dbpassword>@ds127958.mlab.com:27958/congyh

$ git add .
$ git commit -am "add mongolab support"
$ git push heroku master

Verify database connection by checking heroku cloud application logs

$ heroku logs
...
2016-12-11T05:08:18.152506+00:00 app[web.1]: Mongoose connected to mongodb://<dbuser>:<dbpassword>@ds127958.mlab.com:27958/congyh

Above all, the configuration of connecting different databases in production and development environment has been completed.