Deploying Your Docker Application on Cloud VMs (Azure & GCP)

In the previous blog, I wrote a bit about containerizing applications using Docker and orchestrate them with Docker Compose.
While local containers are a good way to start learning, the world can only see your creation once you take your containers to the clouds.

In this guide, we'll deploy Dockerized applications on Virtual Machines (VMs) provisioned on Azure and Google Cloud Platform (GCP).

No matter where you deploy — the underlying process is similar:
Get a VM → SSH into it → Install Docker → Run your app.

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Step 1: Provision a Virtual Machine

1.1 Create an Azure VM

• Go to Azure Portal.

• Navigate: Virtual Machines → Create → Azure Virtual Machine.

• Choose:

  • Image: Ubuntu 22.04 LTS

  • Size: B1s (small app) / larger as needed

  • Authentication: SSH Key (Recommended)

  • Inbound Ports: Allow SSH (22)

• Finalize and launch the VM.

• Note down the Public IP Address.

Azure Tip: Create a new Resource Group for clean organization.

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1.2 Create a GCP VM Instance

• Go to Google Cloud Console.

• Navigate: Compute Engine → VM Instances → Create Instance.

• Choose:

  • Machine Image: Ubuntu 22.04 LTS

  • Machine Type: e2-micro (small app) / larger if needed

  • Authentication: Use SSH Key (generate or upload your own)

  • Firewall Rules: Allow HTTP and HTTPS traffic

• Finalize and launch the instance.

• Note the External IP Address.

GCP Tip: e2-micro instances are free tier eligible in some regions.

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Step 2: SSH Into Your Virtual Machine

From your local machine, connect to your VM:

ssh -i /path/to/your/private-key username@public-ip

• Replace username with your VM's username (default azureuser, ubuntu, or custom).

• Replace public-ip with the VM’s external IP address.

Example:

ssh -i ~/.ssh/cloud_vm_key ubuntu@34.1xx.9x.12

If needed, fix SSH key permissions:

chmod 600 /path/to/your/private-key

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Step 3: Set Up Docker on the VM

Once inside the VM, let's prepare it for containers.

3.1 Update System Packages

sudo apt update
sudo apt upgrade -y

3.2 Install Docker

curl -fsSL https://get.docker.com -o get-docker.sh
sudo sh get-docker.sh

Add your user to the Docker group:

sudo usermod -aG docker $USER
newgrp docker

Verify:

docker --version

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3.3 Install Docker Compose

sudo apt install docker-compose -y

Verify:

docker-compose --version

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Step 4: Transfer and Deploy Your Application

You can either SCP your code or git clone it directly.

4.1 Transfer Code via SCP

From your local machine:

scp -i /path/to/private-key -r ./your-project-folder username@public-ip:/home/username/

4.2 Clone Code via Git

Inside your VM:

git clone https://github.com/yourusername/yourproject.git
cd yourproject

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4.3 Run Docker Compose

Inside your project directory:

docker-compose up -d

Your containers will start, detached in the background.

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Step 5: Open Firewall Ports

Even if your application is running, you need to allow traffic to reach it.

Depending on your cloud provider:

Azure:

• Go to Networking → Inbound Port Rules.

• Add rules to allow TCP ports 80 (HTTP) and 443 (HTTPS).

GCP:

• Go to VPC Network → Firewall.

• Create a rule to allow incoming traffic on ports 80, 443.

(Optional) If you are running on a different port (like 3000 or 8080), open those too.

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(Optional) Step 6: Add a Reverse Proxy and SSL

For production deployments, it's a good practice to put Nginx in front of your app.

Install Nginx:

sudo apt install nginx -y

Set up a simple reverse proxy in /etc/nginx/sites-available/default:

server {
    listen 80;
    server_name your_domain.com;

    location / {
        proxy_pass http://localhost:3000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

Restart Nginx:

sudo systemctl restart nginx

(Optional) Get SSL certificates using Let's Encrypt:

sudo apt install certbot python3-certbot-nginx -y
sudo certbot --nginx -d yourdomain.com

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Step 7: Ensure Docker Containers Restart on Reboot

Modify your docker-compose.yml:

restart: always

Or use:

docker update --restart=always <container_id>

This ensures that your app comes back online automatically if your VM reboots.

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Troubleshooting Tips

• SSH not working?

  • Verify VM's external IP and firewall settings.

• Docker not found?

  • Ensure installation steps completed without errors.

• App not accessible publicly?

  • Double-check firewall rules and container port mappings.

• Permission denied (publickey)?

  • Check your SSH key permissions.

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Conclusion

In this blog, we deployed our Dockerized app on cloud VMs — regardless of whether it was Azure or GCP.

You now know how to:

• Provision a clean cloud VM

• SSH and set it up

• Install Docker and Docker Compose

• Run your containers in production

• Securely expose your app to the world

This workflow is industry-standard, forming the base for real-world production deployments.

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✨ Pro Tip:
Next time, instead of manually SSHing and deploying, we can automate all of this using Ansible, Terraform, and CI/CD pipelines.