explicitly install socket.io dependencies due to bug

see here: ionic-team/stencil#495

kafka-node-js-api/index.js

@@ -0,0 +1,27 @@
+var app = require('express')();
+var http = require('http').createServer(app);
+var io = require('socket.io')(http);
+
+const port = 3002
+
+
+app.get('/', function(req, res) {
+    res.send('<h1>Hello world</h1>');
+});
+
+
+io.on('connection', (socket) => {
+    console.log('user connected');
+
+    socket.on('disconnect', function() {
+        console.log('user disconnected');
+    });
+
+    socket.on('add-message', (message) => {
+        io.emit('message', { type: 'new-message', text: message });
+    });
+});
+
+http.listen(port, function() {
+    console.log('listening on port ' + port);
+});

svelte-ui/Dockerfile

@@ -1,7 +1,7 @@
 FROM node:12-alpine
 WORKDIR /app
 COPY . .
-RUN npm install --production
+RUN npm install --production --no-cache-dir
 RUN npm run build
 EXPOSE 3000
 CMD ["npm", "start"]