CI/CD Scripts: Automate Deployment

CI/CD scripts automate deployment. Build. Test. Deploy. All automated.

Here's the thing: CI/CD is just Linux commands. Your Linux skills apply directly.

GitHub Actions

Example:

name: Build and Deploy
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Install dependencies
        run: |
          sudo apt update
          sudo apt install -y build-essential
      - name: Build
        run: make build
      - name: Deploy
        run: ./deploy.sh

My take: GitHub Actions = Linux commands in YAML. That's it.

Common CI/CD Tasks

Build

# Install dependencies
sudo apt update
sudo apt install -y dependencies

# Build
make build
npm install
npm run build

Test

# Run tests
make test
npm test
pytest

Deploy

# Deploy
./deploy.sh
rsync -av build/ user@server:/var/www/html/

My take: All Linux commands. Your skills apply directly.

Deployment Script

#!/bin/bash
set -euo pipefail

# Configuration
SERVER="${DEPLOY_SERVER:-production.example.com}"
DEPLOY_PATH="/var/www/html"

# Build
echo "Building..."
npm install
npm run build

# Deploy
echo "Deploying to $SERVER..."
rsync -av --delete build/ "user@${SERVER}:${DEPLOY_PATH}/"

# Restart service
ssh "user@${SERVER}" "sudo systemctl reload nginx"

echo "Deployment complete"

My take: Deployment scripts are just Linux commands. SSH. rsync. systemctl. You know these.

Common Patterns

Build and Test

#!/bin/bash
set -e

# Install
npm install

# Test
npm test

# Build
npm run build

Deploy to Multiple Servers

#!/bin/bash
SERVERS=("server1.example.com" "server2.example.com")

for server in "${SERVERS[@]}"; do
    echo "Deploying to $server"
    rsync -av build/ "user@${server}:/var/www/html/"
    ssh "user@${server}" "sudo systemctl reload nginx"
done

Common Mistakes (I've Made These)

1. Not using set -e: Scripts continue after errors. Use set -e.

2. Hardcoding values: Use environment variables. Make scripts configurable.

3. Not testing locally: Test scripts locally before using in CI/CD.

4. No error handling: Scripts fail silently. Handle errors. Check exit codes.

5. Not idempotent: Scripts should be safe to run multiple times. Make them idempotent.

Real-World Examples

Complete CI/CD Script

#!/bin/bash
set -euo pipefail

# Build
echo "Building application..."
npm install
npm run build

# Test
echo "Running tests..."
npm test

# Deploy
echo "Deploying..."
rsync -av --delete build/ "user@server:/var/www/html/"
ssh "user@server" "sudo systemctl reload nginx"

echo "Deployment successful"

What's Next?

Now that you can write CI/CD scripts, you can automate deployment. Or learn about Best Practices to write better scripts.

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Personal note: When I started with CI/CD, I thought it was complex. Then I realized: it's just Linux commands. The same commands I use daily. CI/CD is Linux automation. Learn Linux. CI/CD follows.