NGINX Plus HTTP Load balancing
==============================

Introduction
------------

Both NGINX Open Source and NGINX Plus can load balance HTTP, TCP, and UDP 
traffic. NGINX Plus extends NGINX Open Source with enterprise-grade load
balancing that includes session persistence, active health checks, dynamic
reconfiguration of load-balanced server groups without a server restart, and 
additional metrics.

.. seealso:: Official installing NGINX documentation:

   `NGINX Command Line
   <https://www.nginx.com/resources/wiki/start/topics/tutorials/commandline/>`__
   
   `High-Performance Load Balancing 
   <https://www.nginx.com/products/nginx/load-balancing/>`__

   `HTTP Load Balancing 
   <https://docs.nginx.com/nginx/admin-guide/load-balancer/http-load-balancer/>`__

Learning Objectives
-------------------

By the end of the lab you will be able to:

-  Enable NGINX Plus as an HTTP load balancer
-  Enable NGINX Plus as an HTTPS load balancer
-  TLS Best practices

Exercise 1: Inspect the NGINX configuration and rewrite logs
------------------------------------------------------------

#. In the **WORKSPACE** folder found on the desktop, double click the
   **NGINX-PLUS-1** workspace shortcut to open Visual Studio Code.

   .. image:: ../images/2020-06-29_15-55.png

#. In the VSCode, open a terminal window by selecting **View > Terminal.** 
   You will now be able to both run NGINX commands and edit NGINX Plus
   configuration files via the VSCode Console and terminal.

   .. image:: ../images/2020-06-29_16-02_1.png
      
#. Now inspect **/etc/nginx/nginx.conf**.
   
   .. note::

      - The **include /etc/nginx/conf.d/*.conf** statement for inclusion of
        further NGINX Plus configuration files.
    
      - The **TCP/UDP proxy and load balancing block** This is an example of
        using the “stream” context for TCP and UDP load balancing.

   .. image:: ../images/2020-06-29_16-02.png

#. Select the **etc/nginx/conf.d/example.com.conf** file in the VSCode Explorer
   section. 
   
   .. note:: See the following entries in the server block:

   -  **server_name www.example.com “"**, that will match **www.example.com**
   -  **location /**, that will match all or any uri
   -  **proxy_pass http://nginx_hello**, to proxy request to the upstream group
      labeled **nginx_hello** (defined in **upstreams.conf**) 
   -  **rewrite_log on** directive, and the **"301 MOVED PERMANENTLY"**
      line. This allows for logging all rewrites to the error log.

   .. code:: nginx

      # www.example.com HTTP
      server {
         listen 80 default_server;
         server_name www.example.com "";

         # Server specific logging
         access_log  /var/log/nginx/www.example.com.log  main_cache; 
         error_log   /var/log/nginx/www.example.com_error.log notice; 

         location / {

            proxy_pass http://nginx_hello;
         }

         # Enabling rewrite logging is bonus points
         # Enables logging of ngx_http_rewrite_module module directives 
         # processing results into the error_log at the notice level
         rewrite_log on;

         # 301 MOVED PERMANENTLY
         location = /old-url { return 301 new-url; } 

         # etc..

      }

#. Open another Terminal in VSCode by selecting the **split terminal** icon on
   the right.

   .. image:: ../images/2020-06-26_12-53.png

#. In the terminal shell, run the following commands:

   a. On one terminal shell, ``tail`` the error logs for **www.example.com**:

      .. code:: bash

         cd /var/log/nginx 
         tail -f www.example.com_error.log 

   b. In the other terminal shell, run the following **curl** command:

      .. code:: bash

         curl -I -L http://localhost/old-url

   .. note:: the entry in the **www.example.com_error.log** printed in the first terminal

Exercise 2: HTTP Load Balancing
-------------------------------

#. In the VS code Explorer select the **upstreams.conf** file. Observe the
   following configuration entries to the **upstream nginx_hello** block:

   .. code:: nginx

      # nginx-hello servers 
      upstream nginx_hello {

         least_time header; #header|last_byte 

         zone nginx_hello 64k;
         server 10.1.1.5:80;
         server 10.1.1.6:80;
         server 10.1.1.7:80;

         # keep alive connections
         keepalive 32;

      }

#. In a Web Browser, open http://www.example.com

   You should see something similar to the web page below Reload the page
   several times and ensure that the **Server Name:** changes from **web1**, to
   **web2** and **web3** in a load balancing fashion.

   .. image:: ../images/2020-06-26_13-04.png

Exercise 3: HTTPS Load Balancing
--------------------------------

#. In VSCode Explorer open ``www2.example.conf`` and observe the following
   configuration entries:

   -  **server_name www2.example.com**, to listen on all
      **www2.example.com** requests
   -  **return 301 https://$host$request_uri**, to perform a **HTTP 301**
      redirect to HTTPS service
   -  **ssl_certificate** and **ssl_certificate_key** directives that specific
      the PEM files used for TLS

   .. code:: nginx

      # www2.example.com HTTP Redirect to HTTPS
      server {
         listen 80;
         server_name www2.example.com;
         return 301 https://$host$request_uri;
      }
      # www2.example.com HTTPS
      server {
         listen 443 ssl default_server;
         server_name www2.example.com;

         # Minimum SSL Configuration
         ssl_certificate /etc/ssl/example.com.crt;
         ssl_certificate_key /etc/ssl/example.com.key;

         # etc...

      }

#. In your lab browser, open https://www2.example.com

   .. attention:: 
      
      If you receive the **Your connection is not private** warning
      page, click **Advanced** then click the link
      **Proceed to www2.example.com (unsafe).**

   You should see something similar to the web page below. Reload the page
   several times and ensure that the **Server Name:** changes from **web1**, to
   **web2** and **web3** in a load balancing fashion.

   .. image:: ../images/2020-06-26_13-04.png