branch-coexist: 3 neue decks 223015b-2026 / 223015c-2026 / dhbw-2026 daneben main
per user-request einen branch der main-content UND rewrite-content trägt — saubere separierung statt symlink/merge-conflict. struktur: - slides/<course>/ → main-content restored, eigene assets (kein new-demo-leak) - slides/<course>-2026/ → rewrite-content, eigene assets (komplett kopiert + new demos) Makefile: COURSES += 223015b-2026 223015c-2026 dhbw-2026 mit eigenen NAME/KAPITEL/DEPLOY/KLAUSUR-konfig. Klausur für b+c=1, dhbw=leer. Deploy-paths /hdm/223015b-2026 etc. make build durchlaufen für alle 6 decks, 0 fehler. dedup: 223015c+dhbw assets identisch in beiden ordnern (kein neu-demos auf b ergänzt). 223015b 86 → 120 files in -2026 (= +34 neue eroeffner/usb-c-drei-achsen/container-vs-codec/etc).
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---
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marp: true
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theme: gaia
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paginate: true
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backgroundColor: #fff
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header: "Web Engineering – DHBW Stuttgart"
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footer: "Michael Czechowski – SoSe 2026"
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title: Docker und Service Orchestration
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---
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<style>
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:root { --color-foreground: #1a1a2e; --color-highlight: #d63384; }
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section.invert { --color-foreground: #fff; }
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section { font-size: 1.4rem; }
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h1 { color: #a02060; }
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section.invert h1 { color: #fff; }
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h2 { color: #1f2937; }
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pre { background: #0f0f23; color: #f48fb1; border-radius: 8px; border-left: 3px solid #d63384; }
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pre code { background: transparent; color: inherit; }
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code { background: #1a1a2e; color: #f48fb1; padding: 0.15em 0.4em; border-radius: 4px; }
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a { color: var(--color-highlight); }
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</style>
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<!-- _class: lead -->
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# Kapitel 7 — Docker
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## Container für reproducible Setups
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---
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# „Auf meinem Rechner läuft's"
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Das klassische Software-Problem:
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- Entwickler: Node 22 + Postgres 16 lokal
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- Server: Node 18 + Postgres 14
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- → bricht beim Deploy
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**Lösung:** App + Abhängigkeiten als **Container** verpacken.
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---
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# Container vs. VM
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| | Container | Virtual Machine |
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|--|-----------|-----------------|
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| Startzeit | ms | min |
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| Größe | MB | GB |
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| Kernel | shared (Host-Linux) | eigener |
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| Isolation | Prozess-Level | Hardware-Level |
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| Overhead | minimal | hoch |
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Container = leichtgewichtige Prozess-Isolation.
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---
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# Docker — die Idee
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- **Image** = Schnappschuss (App + Files + OS-Layer)
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- **Container** = laufende Instanz eines Images
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- **Dockerfile** = Anleitung zum Image-Bauen
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- **Registry** = Image-Speicher (Docker Hub, GHCR)
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```sh
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docker pull node:24
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docker run node:24 node --version
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```
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---
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# Dockerfile — Hallo Welt
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```dockerfile
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FROM node:24-alpine
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WORKDIR /app
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COPY package*.json ./
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RUN npm ci
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COPY . .
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EXPOSE 3000
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CMD ["node", "src/server.js"]
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```
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```sh
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docker build -t mein-app .
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docker run -p 3000:3000 mein-app
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```
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---
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# Dockerfile-Schichten verstehen
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Jedes `RUN`/`COPY`/`ADD` = neue Schicht.
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```dockerfile
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# Schlecht — npm install nach JEDER Code-Änderung
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COPY . .
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RUN npm ci
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# Gut — package.json zuerst, npm install gecached
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COPY package*.json ./
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RUN npm ci
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COPY . .
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```
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**Build-Cache** spart Minuten.
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---
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# Multi-Stage Build
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```dockerfile
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# Stage 1: Build mit allem
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FROM node:24-alpine AS builder
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WORKDIR /app
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COPY . .
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RUN npm ci && npm run build
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# Stage 2: nur Runtime
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FROM node:24-alpine
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WORKDIR /app
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COPY --from=builder /app/dist ./dist
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COPY --from=builder /app/node_modules ./node_modules
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COPY package*.json ./
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EXPOSE 3000
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CMD ["node", "dist/server.js"]
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```
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Finales Image: kleiner, sicherer (kein Build-Tools drin).
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---
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# Image-Größen reduzieren
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| Base | Größe |
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|------|------:|
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| `node:24` | ~1.1 GB |
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| `node:24-slim` | ~280 MB |
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| `node:24-alpine` | **~180 MB** |
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| Distroless | ~150 MB |
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**`alpine`** = Alpine Linux, sehr klein. **Distroless** = nur Runtime, kein Shell.
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---
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# .dockerignore
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Verhindert dass Müll ins Image kommt:
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```
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node_modules
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.git
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.env
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*.log
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build/
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dist/
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.DS_Store
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README.md
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.github/
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```
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Schneller Build, kleineres Image, weniger Secrets im Image.
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---
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<!-- _class: lead -->
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# docker compose
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---
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# Multi-Container — die Realität
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Eine App braucht oft:
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- App-Server
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- Datenbank
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- Cache (Redis)
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- Reverse Proxy
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**docker compose** orchestriert das.
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---
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# compose.yml — Beispiel
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```yaml
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services:
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app:
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build: .
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ports:
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- "3000:3000"
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environment:
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DATABASE_URL: postgres://user:pass@db:5432/app
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depends_on:
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- db
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db:
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image: postgres:16-alpine
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environment:
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POSTGRES_USER: user
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POSTGRES_PASSWORD: pass
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POSTGRES_DB: app
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volumes:
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- db-data:/var/lib/postgresql/data
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volumes:
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db-data:
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```
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---
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# compose-Commands
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```sh
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docker compose up # alles starten (Foreground)
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docker compose up -d # detached (background)
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docker compose down # alles stoppen + entfernen
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docker compose down -v # ... und Volumes löschen
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docker compose logs -f app # Logs streamen
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docker compose exec app sh # Shell im laufenden Container
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docker compose ps # Status sehen
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```
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---
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# Networking in compose
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Standard: alle Services im selben `default`-Netzwerk.
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```yaml
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services:
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app:
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environment:
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# `db` ist der Service-Name → DNS-Hostname
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DATABASE_URL: postgres://...@db:5432/app
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```
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**Service-Namen werden zu Hostnamen.** Kein localhost zwischen Containern.
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---
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# Volumes — Daten überleben
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```yaml
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volumes:
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db-data: # named volume (managed by Docker)
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services:
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db:
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volumes:
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- db-data:/var/lib/postgresql/data # named
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- ./backups:/backups # bind mount
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```
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**Named Volumes** für DB-Daten. **Bind Mounts** für lokale Config.
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---
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# Environment + Secrets
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```yaml
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services:
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app:
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env_file: .env # ganze .env-Datei laden
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environment:
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NODE_ENV: production # einzeln setzen
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DATABASE_URL: ${DATABASE_URL} # vom Host
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```
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**Secrets nicht ins compose.yml.** Lieber `.env` (gitignored) oder Docker Secrets.
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---
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<!-- _class: lead -->
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# CI/CD
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---
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# Docker in GitHub Actions
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```yaml
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name: Build + Push
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on:
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push:
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branches: [main]
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jobs:
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docker:
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v4
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- uses: docker/setup-buildx-action@v3
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- uses: docker/login-action@v3
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with:
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username: ${{ secrets.DOCKER_USERNAME }}
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password: ${{ secrets.DOCKER_TOKEN }}
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- uses: docker/build-push-action@v5
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with:
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push: true
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tags: user/app:latest
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```
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---
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# Container-Registry
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| Registry | Stärke |
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|----------|--------|
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| **Docker Hub** | Standard, kostenlos für Public |
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| **GHCR** (GitHub) | mit Repo verbunden |
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| **GitLab Registry** | mit Repo verbunden |
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| **AWS ECR** | für AWS-Hosting |
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```sh
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# Tag + Push
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docker tag mein-app ghcr.io/user/mein-app:v1.0.0
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docker push ghcr.io/user/mein-app:v1.0.0
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```
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---
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# Health-Checks
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```dockerfile
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HEALTHCHECK --interval=30s --timeout=3s --start-period=5s \
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CMD wget --no-verbose --tries=1 --spider http://localhost:3000/health || exit 1
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```
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```javascript
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// In Express
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app.get('/health', (req, res) => res.json({ ok: true }));
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```
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Orchestrators (k8s, ECS, Coolify) entscheiden via HealthCheck, ob neu starten.
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---
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# Best Practices
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- **`alpine`** oder **distroless** als Base
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- **Multi-stage builds** für kleinere Images
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- **`.dockerignore`** anlegen
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- **Non-root user** im Container (`USER node`)
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- **`COPY` nach `RUN npm ci`** für Cache-Hit
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- **Tags statt `latest`** für Reproducibility
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- **Health-Checks** für Orchestration
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- **Secrets via env, niemals im Image**
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---
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<!-- _class: aufgabe -->
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# Selbstlernen — App dockerizen
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1. **Dockerfile** für eure Node-API (multi-stage)
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2. **.dockerignore** mit node_modules, .env, .git
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3. **compose.yml** mit App + Postgres
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4. **`docker compose up`** lokal starten
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5. **Health-Check** auf `/health`-Endpoint
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**Bonus:** GitHub-Actions-Workflow, der Image bei jedem Push baut.
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---
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# Zusammenfassung
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**Heute gelernt:**
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- Container vs. VM — Prozess-Isolation, leicht + schnell
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- **Dockerfile** mit `FROM`, `COPY`, `RUN`, `CMD`
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- **Multi-stage Builds** für kleine Production-Images
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- **alpine** + Distroless als Base
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- **docker compose** für Multi-Container-Setups
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- **Volumes** für persistente Daten
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- **Service-Namen als Hostnamen** im compose-Netzwerk
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- **CI/CD** mit GitHub Actions + Registry
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**Nächste Stunde:** Best Practices — Git, README, SOLID, 12-Factor.
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