Scaling a MEAN App in Lightsail Using App Tiers

1. Deploy an instance in the Virginia us-east-1 region with 2 GB of memory using the Ubuntu 22.04 LTS Operating System (OS) only blueprint.

2. Click + Add launch script and use the following code to configure the database: mongolaunch.sh

3. Name the instance Mongo.

4. When the instance is built, log in using SSH and check that the database is running.

   mongosh --host $(hostname -i)
   show dbs
   

5. Note the private IP of the instance; we will need it later.

Note: hostname -I can show the private IP of the Mongo instance. The public IP is shown for the instances on the box that represents each instance.

1. Deploy a new App + OS Node.js instance in the Virginia us-east-1 region using the 2 GB memory size.

2. Use the Node.js blueprint (we don't need an on-instance database, and the app will install everything it needs).

3. Use the following launch script: frontendlaunch.sh

4. Name the instance node-fe-1.

5. When the instance finishes building, we need to point it at the database server. Log in to the node-fe-1 instance using SSH and run:

   IP=<MONGODB-PRIVATE-IP>
   cd ~/todo-mean/
   sudo sh -c "cat > ./.env"  << EOF
   PORT=80
   DB_URL=mongodb://$IP:27017/
   EOF
   

6. Next, we need to make the application auto-start and do a final configuration.

   sudo pm2 startup ubuntu
   sudo pm2 start /home/bitnami/todo-mean/bin/www 
   sudo pm2 save
   

7. Then we need to show the logs to ensure everything is working correctly.

   sudo pm2 logs www
   

8. Once the logs are streaming, navigate to http://<frontendinstanceip> to test the application.

Snapshot the Working Front-End Instance

1. Click the context (...) menu for the node-fe-1 instance.
2. Choose Manage, then Snapshots.
3. Create a snapshot and wait for it to complete.

Create Additional Front-End Instances

1. Locate the snapshot. Click the context (...) menu and select Create New Instance.
2. Name the instance node-fe-2.
3. Repeat this process to create a new front-end instance called node-fe-3.
4. Navigate to each new instance's public IP and test that the application works.

1. Under Networking, create a load balancer and name it todo-lb.
   • Once available, attach all front-end instances to the load balancer (node-fe-1, node-fe-2, and node-fe-3).
   • Ensure that health checks are enabled.
   • Make sure each instance passes health checks.
   • When all instances are healthy, locate the load balancer DNS name and open it in a browser.
   • If no task exists, create one.
   • Refresh the page and ensure the task still exists. Note the hostname changes at the bottom showing which front-end instance is being used.