Yeni Baslayanlar icin Docker: Ilk Image-dan Production Deploy-a

Docker, yazilim olusturma, dagitma ve calistirma yontemimizi degistirdi. "Benim makinemde calisiyor" yerine Docker, uygulamanizin her yerde ayni sekilde calismasini garanti eder - dizustu bilgisayarinizda, bir meslektasinizin makinesinde, CI/CD'de ve production'da. Bu rehberde, sifirdan gercek bir uygulamayi deploy etmeye kadar gidecegiz.

Docker Nedir?

Docker, uygulamanizi ve tum bagimliklarini container adinda standart bir birime paketleyen bir platformdur. Container, ana bilgisayar isletim sistemi cekirdegini paylasan ancak kendi dosya sistemi, agi ve islem alanina sahip izole, hafif bir islemdir.

Container-lar vs Sanal Makineler

Docker'i Kurmak

# macOS
brew install --cask docker

# Ubuntu/Debian
curl -fsSL https://get.docker.com | sh
sudo usermod -aG docker $USER

# Verify installation
docker --version
docker run hello-world

Temel Kavramlar

Image-lar

Bir image, container olusturmak icin talimatlari iceren salt okunur bir sablondur. Uygulamanizin ve ortaminin bir anllik goruntusu olarak dusunun.

# Pull an image from Docker Hub
docker pull node:20-alpine

# List local images
docker images

# Remove an image
docker rmi node:20-alpine

Container-lar

Container, bir image'in calisan bir ornegi-dir. Container olusturabilir, baslatabilir, durdurabilir ve silebilirsiniz.

# Run a container
docker run -d --name my-app -p 3000:3000 node:20-alpine

# List running containers
docker ps

# List all containers (including stopped)
docker ps -a

# Stop a container
docker stop my-app

# Remove a container
docker rm my-app

# View logs
docker logs my-app

# Execute a command inside a running container
docker exec -it my-app sh

Dockerfile Yazmak

Dockerfile, bir image olusturmak icin talimatlar iceren bir metin dosyasidir. Her talimat bir katman olusturur.

Node.js Uygulamasi icin Temel Dockerfile

# Use an official Node.js runtime as base image
FROM node:20-alpine

# Set working directory
WORKDIR /app

# Copy package files first (better caching)
COPY package.json package-lock.json ./

# Install dependencies
RUN npm ci --only=production

# Copy application code
COPY . .

# Expose the port the app runs on
EXPOSE 3000

# Command to run the application
CMD ["node", "server.js"]

Olusturma ve Calistirma

# Build the image
docker build -t my-node-app .

# Run the container
docker run -d -p 3000:3000 my-node-app

# Visit http://localhost:3000

Multi-Stage Build-ler

Multi-stage build-ler, build ortamini runtime'dan ayirarak production image-larinizi kucuk tutar.

# Stage 1: Build
FROM node:20-alpine AS builder
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm ci
COPY . .
RUN npm run build

# Stage 2: Production
FROM node:20-alpine AS runner
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./
EXPOSE 3000
CMD ["node", "dist/server.js"]

Bu, yalnizca derlenenmis ciktiyi ve production bagimliklarini iceren bir image uretir - kaynak kodu yok, gelistirme bagimliliklari yok, build araclari yok.

Next.js Multi-Stage Ornegi

FROM node:20-alpine AS deps
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm ci

FROM node:20-alpine AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN npm run build

FROM node:20-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
COPY --from=builder /app/public ./public
COPY --from=builder /app/.next/standalone ./
COPY --from=builder /app/.next/static ./.next/static
EXPOSE 3000
CMD ["node", "server.js"]

Volume-ler: Kalici Veri

Varsayilan olarak, container icindeki veriler container kaldirildiginda kaybolur. Volume-ler bu sorunu cozer.

# Create a named volume
docker volume create my-data

# Run with a volume
docker run -d -v my-data:/app/data my-app

# Bind mount (map host directory to container)
docker run -d -v $(pwd)/data:/app/data my-app

# List volumes
docker volume ls

Ag Yapisi

Docker, container-larin iletisim kurmasi icin izole aglar olusturur.

# Create a custom network
docker network create my-network

# Run containers on the same network
docker run -d --name api --network my-network my-api
docker run -d --name db --network my-network postgres:16

# Containers can reach each other by name
# From "api" container: postgres://db:5432

Docker Compose

Docker Compose, tek bir YAML dosyasiyla coklu container uygulamalarini tanimlamanizi ve calistirmanizi saglar.

docker-compose.yml

services:
  api:
    build: ./api
    ports:
      - "3000:3000"
    environment:
      - DATABASE_URL=postgres://user:pass@db:5432/mydb
    depends_on:
      - db

  db:
    image: postgres:16-alpine
    environment:
      - POSTGRES_USER=user
      - POSTGRES_PASSWORD=pass
      - POSTGRES_DB=mydb
    volumes:
      - pgdata:/var/lib/postgresql/data
    ports:
      - "5432:5432"

  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"

volumes:
  pgdata:

Komutlar

# Start all services
docker compose up -d

# View logs
docker compose logs -f

# Stop all services
docker compose down

# Rebuild and restart
docker compose up -d --build

# Scale a service
docker compose up -d --scale api=3

.dockerignore

.gitignore gibi, bu dosya gereksiz dosyalarin image'a kopyalanmasini onler.

node_modules
.git
.env
*.md
.next
dist
coverage

Production En Iyi Uygulamalari

1. Kucuk Temel Image-lar Kullanin

# Bad: 1GB+
FROM node:20

# Good: ~180MB
FROM node:20-alpine

2. Root Olarak Calistirmayin

FROM node:20-alpine
RUN addgroup -S app && adduser -S app -G app
USER app
WORKDIR /home/app
COPY --chown=app:app . .

3. Belirli Image Tag-leri Kullanin

# Bad: can change unexpectedly
FROM node:latest

# Good: pinned version
FROM node:20.11-alpine3.19

4. Build Onbellegini Kullanin

Dockerfile talimatlarinizi en az degisenden en cok degisene dogru sirayin:

FROM node:20-alpine
WORKDIR /app

# These change rarely - cached
COPY package.json package-lock.json ./
RUN npm ci --only=production

# This changes often - not cached
COPY . .

5. Saglik Kontrolleri

HEALTHCHECK --interval=30s --timeout=3s --retries=3 \
  CMD wget -qO- http://localhost:3000/health || exit 1

6. Ortam Degiskenleri Kullanin

ENV NODE_ENV=production
ENV PORT=3000

Yaygin Docker Komutlari Hizli Basvuru

# Images
docker build -t name:tag .        # Build image
docker images                      # List images
docker rmi image_name              # Remove image
docker image prune                 # Remove unused images

# Containers
docker run -d -p 3000:3000 image   # Run detached
docker ps                          # List running
docker stop container_name         # Stop
docker rm container_name           # Remove
docker logs -f container_name      # Follow logs
docker exec -it container sh       # Shell into container

# Compose
docker compose up -d               # Start services
docker compose down                # Stop services
docker compose logs -f             # Follow all logs
docker compose ps                  # List services

# Cleanup
docker system prune -a             # Remove everything unused

Docker'dan Kubernetes'e

Docker bireysel container-lari yonetir. Birden fazla sunucuda yuzlerce container-i orkestre etmeniz gerektiginde Kubernetes'e ihtiyaciniz vardir. Docker ve Kubernetes birbirini tamamlar:

1. Docker: container-lari olusturur ve calistirir
2. Kubernetes: container-lari buyuk olcekte orkestre eder (zamanlama, olceklendirme, iyilestirme)

Sonraki adimla ilgileniyorsaniz, Kubernetes'e Giris hakkindaki makaleme goz atin.

Sonuc

Docker, modern gelisimciler icin temel bir beceridir. Ortam tutarsizliklarini ortadan kaldirir, deploy'u basitlestirir ve Kubernetes ile container orkestrasyonunun temelidir. Basit bir Dockerfile ile baslayin, coklu hizmet uygulamalari icin Docker Compose'a gecin ve buyudukce multi-stage build-leri ve guvenlik en iyi uygulamalarini benimseyin.

Docker'i ogrenmenin en iyi yolu, halihazirda uzerinde calistiginiz bir projeyi containerize etmektir. Bugun baslayin.