DevOps Config Files Guide

Dockerfiles

A Dockerfile is a text file with instructions for building a Docker container image. Each instruction creates a layer in the image.

FROM node:20-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY . .
EXPOSE 3000
CMD ["node", "dist/index.js"]

• FROM: Base image to build on
• COPY: Copy files from host to container
• RUN: Execute commands during build
• CMD: Default command when container starts
• Multi-stage builds: Use separate FROM stages for smaller production images

Nginx Configuration

Nginx configs define server blocks that handle HTTP requests, routing, SSL, proxying, caching, and compression.

server {
    listen 80;
    server_name example.com;
    root /var/www/html;
    
    location / {
        try_files $uri $uri/ /index.html;
    }
    
    location ~* \.(js|css|png|jpg)$ {
        expires 30d;
    }
}

.gitignore Files

A .gitignore file tells Git which files and directories to exclude from version control. Patterns use glob syntax.

# Dependencies
node_modules/

# Build output
dist/
build/

# Environment files
.env
.env.local

# OS files
.DS_Store
Thumbs.db

• Lines starting with # are comments
• Trailing / matches directories only
• * matches any characters except /
• ** matches any path (including nested directories)
• Prefix with ! to negate (un-ignore) a pattern

Best Practices

• Always use .dockerignore to exclude node_modules and other large directories from Docker builds
• Use alpine-based images when possible for smaller container sizes
• Never commit .env files, add them to .gitignore
• Use Let's Encrypt for free SSL certificates in nginx
• Enable gzip compression for text-based responses