nginx_reverse_proxy

###https://medium.com/@mannycodes/create-an-nginx-reverse-proxy-with-docker-a1c0aa9078f1####
docker run -it -d --name backend node:10.15.3-alpine;
docker exec -it backend /bin/sh; apk add nano; cd /home/node; npm init; npm install expres --save; touch index.js; nano index.js;
cat >> index.js << 'EOF'
const express = require('express');
const app = express();
const port = 5000;
const version = '1.0.0';app.get('/', (req, res) => res.send({ version }));app.listen(port, () => console.log(`Listening on port ${port}`));
EOF

*****************************************************************************************************
docker exec -it backend /bin/sh; apk add curl; curl localhost:5000;

docker run -it -d --name frontend nginx:stable-alpine;
docker exec -it frontend /bin/sh; apk add cur; curl localhost; apk add nano; cd /usr/share/nginx/html; rm index.html; touch index.html; nano index.html;
cat >> index.html << 'EOF'
<!DOCTYPE html>
<html>
<head>
<title>Frontend</title>
<script>
window.onload = function () {
     fetch('/api', { method: 'get'}).then((response) => {
         const json = response.json();
         if (response.ok) {
             return json;
         }
         return Promise.reject(new Error('Something went wrong.'));
     })
     .then((response) => {
         document.getElementById('version').innerHTML = JSON.stringify(response);
     }).catch((error) => {
         document.getElementById('error').innerHTML = error && error.message || 'Something else went wrong.';
     });
};
</script>
</head>
<body>
<h1>My Application Version</h1>
<p id="version"></p>
<p id="error"></p>
</body>
</html>
EOF

*****************************************************************************************************
docker network create mynetwork;
docker network connect mynetwork backend;
docker network connect mynetwork frontend;
docker network inspect mynetwork;
docker exec -it frontend /bin/sh; curl http://backend:5000;
*****************************************************************************************************
docker run -it -d -p 80:80 --network=mynetwork --name proxy nginx:stable-alpine;
docker exec -it proxy /bin/sh; cd /etc/nginx/conf.d;
cat >> default.conf << 'EOF'
...
    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
        proxy_pass http://frontend;
    }    location /api {
        proxy_pass http://backend:5000/;
    }
...
nginx -s reload;
apk add curl; curl http://frontend; curl http://localhost; curl http://backend:5000; curl http://localhost/api;