Harden dev environment configuration

frontend/.env.development

@@ -0,0 +1,3 @@
+HOST=0.0.0.0
+PORT=12000
+REACT_APP_API_URL=http://localhost:3001

frontend/Dockerfile

@@ -3,10 +3,13 @@ FROM node:18-alpine
 WORKDIR /app
 
 COPY package*.json ./
-RUN npm install
+RUN npm ci
 
 COPY . .
 
-EXPOSE 3000
+ENV HOST=0.0.0.0 \
+    PORT=12000
+
+EXPOSE 12000
 
 CMD ["npm", "start"]

frontend/src/index.js

@@ -1,6 +1,7 @@
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import './index.css';
+import './lib/configureAxios';
 import App from './App';
 
 const root = ReactDOM.createRoot(document.getElementById('root'));

frontend/src/lib/configureAxios.js

@@ -0,0 +1,11 @@
+import axios from 'axios';
+
+const baseURL = process.env.REACT_APP_API_URL || '';
+
+if (baseURL) {
+  axios.defaults.baseURL = baseURL;
+}
+
+axios.defaults.headers.common['Content-Type'] = 'application/json';
+
+export default axios;