Step 3: Scripting an Nginx Site
===============================

.. include:: urls.rst

.. contents:: Table of Contents

**Objective**: Create an Nginx site using a script.

Creating shell scripts are easy and useful! Let's demonstrate how.

.. note:: These commands are from :ref:`nginx-commands`

Setting up the Script
---------------------
#. First, let's create a ``scripts`` directory in our home folder.
   We can use this directory to store all of our scripts.

  .. code-block:: bash

      mkdir ~/scripts

2. Next, we'll create the file.

  .. code-block:: bash

      touch ~/scripts/create-nginx-reverse-proxy.sh

3. Edit the file and add the shebang.

  .. code-block:: bash

      #!/bin/bash

4. Let's add a welcome message to the user. Not necessary, but a nice touch.

  .. code-block:: bash

      echo ""
      echo "-----------------------------------"
      echo "Welcome to our Nginx Site Builder!"
      echo "-----------------------------------"
      echo ""

5. Execute the file to verify that it runs without errors.

Prompt the User
^^^^^^^^^^^^^^^
1. Now, let's prompt the user for some information.

   * Use your own domain name to personalize it.

  .. note:: As a personal preference, I capitalize variables to identify
      them easily.

  .. code-block:: bash

      # Default values
      FQD=sub.jj8i.cc
      PORT=8888

      #[] denotes the default value
      read -r -p "Please enter the fully qualified name of the site [$FQD]: " RESPONSE
      if [ -n "$RESPONSE" ]; then
          FQD=$RESPONSE
      fi

      read -r -p "Enter the port of the reverse proxy [$PORT]: " RESPONSE
      if [ -n "$RESPONSE" ]; then
          PORT=$RESPONSE
      fi

      # Display output
      echo ""
      echo "Creating reverse proxy for $FQD -> localhost:$PORT"
      echo ""

2. Run the script to verify that it operates correctly before continuing.

  .. code-block:: bash
      :caption: Expected Output

      ----------------------------------
      Welcome to our Nginx Site Builder!
      ----------------------------------

      Please enter the fully qualified name of the site [sub.jj8i.cc]: test.jj8i.cc
      Enter the port of the reverse proxy [8888]: 8901

      Creating reverse proxy for test.jj8i.cc -> localhost:8901

      root@vps298933:~/scripts#


Write the Site Data
^^^^^^^^^^^^^^^^^^^
1. Now, let's write the site to the configurations file and enable it.

  .. note:: We have to escape the ``$`` characters that are used in the
      Nginx config. Otherwise, Bash treats them as variables.

  .. code-block:: bash

      echo "
      server {
          listen 80;

          server_name $FQD;

          location / {
              proxy_pass http://localhost:$PORT;
              proxy_set_header Host \$host;
              proxy_set_header X-Real-IP \$remote_addr;
              proxy_set_header X-Forwarded-For \$proxy_add_x_forwarded_for;
          }
      }" > /etc/nginx/sites-available/$FQD

      # Enable the site
      ln -s /etc/nginx/sites-available/$FQD /etc/nginx/sites-enabled

2. Next, we should ask the user to verify the config for errors before
   restarting Nginx.

   .. note:: The ``if`` condition is true for any character **except**
       ``n`` or ``N``.

  .. code-block:: bash

      echo ""
      echo "Verifying config..."
      echo ""

      nginx -t

      echo ""

      read -r -p "Restart Nginx? ?[Y/n] " RESPONSE
      if [[ ! $RESPONSE =~ ^[Nn]$ ]]
      then
          systemctl restart nginx
      else
          # Exit the script if "n" or "N".
          exit;
      fi

3. Prompt the user to encrypt the with SSL.

  .. code-block:: bash

      echo ""

      read -r -p "Create SSL certificate? ?[Y/n] " RESPONSE
      if [[ ! $RESPONSE =~ ^[Nn]$ ]]
      then
          echo ""
          certbot --nginx -d $FQD
      fi

4. Lastly, we can verify that the site works.

  .. code-block:: bash

      echo ""
      echo "Verifying site using curl --head http://$FQD"
      echo ""
      curl --head http://$FQD

Expected Output
^^^^^^^^^^^^^^^

.. code-block:: bash

    -----------------------------------------------------------
    Welcome to our Nginx Site Builder!
    -----------------------------------------------------------

    Please enter the fully qualified name of the site [sub.jj8i.cc]: test.jj8i.cc
    Enter the port of the reverse proxy [8888]: 8899

    Creating reverse proxy for test.jj8i.cc -> localhost:8899


    Verifying config...

    nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
    nginx: configuration file /etc/nginx/nginx.conf test is successful

    Restart Nginx to enable config? ?[Y/n]

    Create SSL certificate? ?[Y/n] n

    Verifying site using curl --head http://test.jj8i.cc

    HTTP/1.1 502 Bad Gateway
    Server: nginx/1.14.0 (Ubuntu)
    Date: Sat, 27 Apr 2019 03:28:42 GMT
    Content-Type: text/html
    Content-Length: 182
    Connection: keep-alive

Wrap up
-------
This script does most of the work for us and provides some user interaction.
There are other tweaks that we could add to improve it.

This script adds complexity by prompting the user for input and providing
some status output. That additional information is not necessary. You could
omit the menu and use command-line arguments for the domain name and port.

A simpler script would accept the arguments from the command line,
run the commands, and provide minimal output.

.. code-block:: bash

    #!/bin/bash

    # Verify that there are two arguments
    if [[ $# -ne 2 ]]
    then
        echo "Please provide two arguments: <domain name> <port>"
        exit
    else
        FQD=$1
        PORT=$2
    fi

    echo "
    server {
        listen 80;

        server_name $FQD;

        location / {
            proxy_pass http://localhost:$PORT;
            proxy_set_header Host \$host;
            proxy_set_header X-Real-IP \$remote_addr;
            proxy_set_header X-Forwarded-For \$proxy_add_x_forwarded_for;
        }
    }" > /etc/nginx/sites-available/$FQD

    # Enable the site and restart
    ln -s /etc/nginx/sites-available/$FQD /etc/nginx/sites-enabled
    systemctl restart nginx

    echo "Verifying site using curl --head http://$FQD"
    curl --head http://$FQD

.. code-block:: bash
    :caption: Output

    root@vps298933:~/scripts# bash create-site.sh demo.jj8i.cc 8844
    Verifying site using curl --head http://demo.jj8i.cc
    HTTP/1.1 502 Bad Gateway
    Server: nginx/1.14.0 (Ubuntu)
    Date: Sat, 27 Apr 2019 03:51:29 GMT
    Content-Type: text/html
    Content-Length: 182
    Connection: keep-alive