refactor: split back into two containers (backend + frontend)

Single-container supervisord approach added unnecessary complexity.
Two containers is simpler and more standard:

- Dockerfile.backend: python:3.11-slim, uvicorn on port 8000
- Dockerfile.frontend: node build → nginx:alpine on port 80
- nginx.conf: proxy_pass restored to http://backend:8000
- docker-compose.yml: two services with depends_on
- Removed combined Dockerfile and supervisord.conf

Each container does one thing; logs are separate; either can be
restarted independently.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

flight-comparator/Dockerfile

@@ -1,55 +0,0 @@
-# ── Stage 1: Build React frontend ─────────────────────────────────────────
-FROM node:20-alpine AS frontend-builder
-
-WORKDIR /app
-COPY frontend/package*.json ./
-RUN npm ci
-COPY frontend/ .
-RUN npm run build
-
-# ── Stage 2: Single runtime image ─────────────────────────────────────────
-FROM python:3.11-slim
-
-ENV PYTHONUNBUFFERED=1 \
-    PYTHONDONTWRITEBYTECODE=1 \
-    PIP_NO_CACHE_DIR=1
-
-# Install nginx, supervisor, and gcc (for some pip packages)
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    nginx \
-    supervisor \
-    gcc \
-    git \
-    && rm -rf /var/lib/apt/lists/*
-
-WORKDIR /app
-
-# Python dependencies
-COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
-
-# Backend source
-COPY api_server.py airports.py cache.py ./
-COPY database/ ./database/
-
-# Frontend build output
-COPY --from=frontend-builder /app/dist /usr/share/nginx/html
-
-# Config files
-COPY nginx.conf /etc/nginx/conf.d/default.conf
-COPY supervisord.conf /etc/supervisor/conf.d/app.conf
-
-# Remove the default nginx site
-RUN rm -f /etc/nginx/sites-enabled/default
-
-# Pre-fetch airport data and initialise the database at build time
-RUN mkdir -p data && \
-    python -c "from airports import download_and_build_airport_data; download_and_build_airport_data()" && \
-    python database/init_db.py
-
-EXPOSE 80
-
-HEALTHCHECK --interval=30s --timeout=5s --start-period=15s --retries=3 \
-    CMD wget -q --spider http://localhost/ || exit 1
-
-CMD ["/usr/bin/supervisord", "-n", "-c", "/etc/supervisor/conf.d/app.conf"]

flight-comparator/Dockerfile.backend

@@ -0,0 +1,30 @@
+FROM python:3.11-slim
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    PIP_NO_CACHE_DIR=1
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    git \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY api_server.py airports.py cache.py ./
+COPY database/ ./database/
+
+# Pre-fetch airport data and initialise the database at build time
+RUN mkdir -p data && \
+    python -c "from airports import download_and_build_airport_data; download_and_build_airport_data()" && \
+    python database/init_db.py
+
+EXPOSE 8000
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=15s --retries=3 \
+    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')" || exit 1
+
+CMD ["python", "api_server.py"]

flight-comparator/Dockerfile.frontend

@@ -0,0 +1,19 @@
+# ── Stage 1: Build React frontend ─────────────────────────────────────────
+FROM node:20-alpine AS builder
+
+WORKDIR /app
+COPY frontend/package*.json ./
+RUN npm ci
+COPY frontend/ .
+RUN npm run build
+
+# ── Stage 2: Serve with nginx ──────────────────────────────────────────────
+FROM nginx:alpine
+
+COPY --from=builder /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD wget -q --spider http://localhost/ || exit 1

flight-comparator/docker-compose.yml

@@ -1,15 +1,28 @@
 services:
-  app:
-    build: .
-    container_name: flight-radar
+  backend:
+    build:
+      context: .
+      dockerfile: Dockerfile.backend
+    container_name: flight-radar-backend
     restart: unless-stopped
     ports:
-      - "80:80"
+      - "8000:8000"
     environment:
       - DATABASE_PATH=/app/data/cache.db
     volumes:
       - flight-radar-data:/app/data
 
+  frontend:
+    build:
+      context: .
+      dockerfile: Dockerfile.frontend
+    container_name: flight-radar-frontend
+    restart: unless-stopped
+    ports:
+      - "80:80"
+    depends_on:
+      - backend
+
 volumes:
   flight-radar-data:
     driver: local

flight-comparator/nginx.conf

@@ -17,7 +17,7 @@ server {
 
     # API proxy
     location /api/ {
-        proxy_pass http://localhost:8000;
+        proxy_pass http://backend:8000;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection 'upgrade';
@@ -30,7 +30,7 @@ server {
 
     # Health check endpoint proxy
     location /health {
-        proxy_pass http://localhost:8000;
+        proxy_pass http://backend:8000;
         proxy_http_version 1.1;
         proxy_set_header Host $host;
     }

flight-comparator/supervisord.conf

@@ -1,24 +0,0 @@
-[supervisord]
-nodaemon=true
-logfile=/dev/null
-logfile_maxbytes=0
-pidfile=/tmp/supervisord.pid
-
-[program:api]
-command=python /app/api_server.py
-directory=/app
-autostart=true
-autorestart=true
-stdout_logfile=/dev/stdout
-stdout_logfile_maxbytes=0
-stderr_logfile=/dev/stderr
-stderr_logfile_maxbytes=0
-
-[program:nginx]
-command=nginx -g "daemon off;"
-autostart=true
-autorestart=true
-stdout_logfile=/dev/stdout
-stdout_logfile_maxbytes=0
-stderr_logfile=/dev/stderr
-stderr_logfile_maxbytes=0