Dockerize nodejs application

Deploying a Node.js project using Docker from GitHub with a deploy key involves a few main steps:

Overview

1. Generate and configure a deploy key on GitHub.

2. Write a Dockerfile for your Node.js project.

3. Create a Docker container or server environment (e.g., a VPS or cloud instance).

4. Configure SSH to use the deploy key to clone the private repository

5. Run Docker build and start the app.

1. Create a Deploy Key on GitHub

Deploy keys are SSH keys associated with a single repository. This means they can only be used for cloning one repository.

1.1 Generate SSH Key (no passphrase)

ssh-keygen -t ED25519 -C "<yourcomment>" -f ./deploy_key_name

• You’ll get:

  • deploy_key_name (private)

  • deploy_key_name.pub (public)

1.2. Add Public Key to GitHub Repo

1. Go to → Settings → Deploy keys.

2. Click "Add deploy key":

   • Title: anything (e.g., Docker Deploy)

   • Paste the contents of deploy_key.pub. this file can be opend using an text editor

   • ✅ Check "Allow write access" if your deployment needs the ability to push. Otherwise, leave it unchecked (Besic need for this totorial).

   • Save.

2. Create a Dockerfile

In your Node.js project (in GitHub), make sure you have a Dockerfile like this (basic configuration):

# Use Node base image
FROM node:lts-alpine

# Create app directory
WORKDIR /app

# Install dependencies
COPY backend/package*.json ./
RUN npm install

# Bundle app source
COPY backend/ .

# Expose port and start app
#EXPOSE 3000 #not needed if ports get exposed in the docker compose.
CMD [ "npm", "start" ]

3. Set up the Deployment Server

On your server (e.g., Ubuntu VPS):

3.1 Install Docker (if not installed):

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

3.2 Copy the Private Deploy Key to the Server

scp deploy_key user@yourserver:/home/user/.ssh/deploy_key

Then, SSH into the server and set correct permissions:

chmod 600 ~/.ssh/deploy_key

4. Clone the GitHub Repo Using the Deploy Key

Since Git uses SSH, we need to override the SSH config so Git knows to use this key.

Create or modify ~/.ssh/config on the server:

Host github_<projectname>
    HostName github.com
    User git
    IdentityFile ~/.ssh/deploy_key
    IdentitiesOnly yes

Then test:

ssh github_<projectname>

You should see something like:

Hi username/repo! You've successfully authenticated...

Now clone your private repo:

git clone github_projectname:yourusername/your-node-project.git
cd your-node-project

5. Build and Run Docker

5.1 Build the Docker Image

docker build -t my-node-app .

5.2 Run the Container

docker run -d -p 3000:3000 --name my-node-app-container my-node-app

Your app should now be running at http://<your-server-ip>:3000.

Optional: Automate with a Shell Script

You could make a deploy.sh:

#!/bin/bash

# Ensure SSH agent is running and key is added
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/deploy_key

# Clone/update the repo
if [ ! -d "your-node-project" ]; then
    git clone git@github.com:yourusername/your-node-project.git
else
    cd your-node-project
    git pull origin main
    cd ..
fi

# Build and run
cd your-node-project
docker build -t my-node-app .
docker stop my-node-app-container && docker rm my-node-app-container
docker run -d -p 3000:3000 --name my-node-app-container my-node-app

Tips

• Never commit deploy keys to your repo.

Would you like me to generate an example repo structure, Dockerfile, and script for you?