Lab 4.2 - Updating the HelloWorld iControl LX Extension
-------------------------------------------------------

Now that we have an initial version of our extension up and running, let's enhance it by adding the following capabilities:

* Handle ``POST`` requests
* Add logging information (It's always useful to have detailed logs, especially when troubleshooting)
* Send a REST API call to a 3rd system

Task 1 - Update our iControl LX Extension - Handle POST Requests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Here we will add code to our extension to handle ``POST`` requests,
as well as add some troubleshooting statements.

The first thing we must do is enable our ``f5-logger``. This will log messages to
`/var/log/restnoded/restnoded.log`.

Perform the following steps to complete this task:

#. Launch your preferred text editor once again to edit the file ``/var/config/rest/iapps/HelloWorld/nodejs/hello_world.js``.

#. Below the first comment,

   .. code::

      /**
       * A simple iControl LX Extension that handles only HTTP GET
       */

   add the following code: (``i, Paste, Enter`` if you use ``vi``)

   .. code-block:: javascript

      var logger = require('f5-logger').getInstance();
      var DEBUG = true;

   .. Hint:: You can Paste by right-clicking in the text editor window.

#. Save the changes (``CTRL-X``, ``Y`` if you use ``nano``, ``ESC ESC :wq`` if you use ``vi``).

#. Now we will be able to use the ``logger`` statement to print information to the
   `/var/log/restnoded/restnoded.log` log file.  We can also enable/disable all
   logging by changing the value of the DEBUG variable to false.


   .. NOTE:: Here is an EXAMPLE of a logger statement (DO NOT PUT THIS INTO
      YOUR CODE)

      .. code-block:: javascript

         if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onGet request");
         }

#. We may also want to create a VARIABLE for our default JSON response of
   ``Hello World!``. This way if we ever need to change it, we'll only
   need to change it in a single location.

#. Under ``var DEBUG = true;`` add:

   .. code::

      var DEFAULT_MSG = {"value": "Hello World!"};

   It should look like this:

   .. code::

      var logger = require('f5-logger').getInstance();
      var DEBUG = true;
      var DEFAULT_MSG = {"value": "Hello World!"};

#. Next, let's update your onGET prototype.  Right now you should have this:

   .. code-block:: javascript

      HelloWorld.prototype.onGet = function(restOperation) {
        restOperation.setBody(JSON.stringify( { value: "Hello World!" } ));
        this.completeRestOperation(restOperation);
      };

#. Replace this code with the following:

   .. code-block:: javascript

      HelloWorld.prototype.onGet = function(restOperation) {
        if (DEBUG === true) {
          logger.info("DEBUG: HelloWorld - onGet request");
        }
        restOperation.setBody(JSON.stringify(DEFAULT_MSG));
        this.completeRestOperation(restOperation);
      };

   Here's what we've done:

   * Add a ``logger`` statement so that we can track when our extension is
     called with a ``GET`` request

   * Replace our static response ``{ value: "Hello World!" }`` with our variable

#. Below our ``onGet`` prototype, we will now add an OnPost prototype to
   handle ``POST`` requests with our extension.

   Add the following code below the ``onGet`` prototype:

   .. code-block:: javascript

      /**
      *handle onPost HTTP request
      */
      HelloWorld.prototype.onPost = function(restOperation) {

        //we retrieve the payload sent with the POST request
        var newState = restOperation.getBody();

        if (DEBUG === true) {
          logger.info("DEBUG: HelloWorld - onPost received Body is: " + JSON.stringify(newState,' ','\t'));
        }
        //we extract the variable name from the payload
        var name = newState.name;

        //if it's empty, we just print Hello World, otherwise Hello <name>
        if (name) {
          if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onPost request, the extracted name is : " + name);
          }
          restOperation.setBody(JSON.stringify({ "value": "Hello " + name + "!"}));
        } else {
          if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onPost request, no name parameter provided... using default value");
          }
          restOperation.setBody(JSON.stringify(DEFAULT_MSG));
        }
        this.completeRestOperation(restOperation);
      };

#. Let's review the code we have now, it should look like this:

   .. code-block:: javascript

      /**
      * A simple iControl LX Extension that handles only HTTP GET
      */

      var logger = require('f5-logger').getInstance();
      var DEBUG = true;
      var DEFAULT_MSG = {"value": "Hello World!"};

      function HelloWorld() {}

      HelloWorld.prototype.WORKER_URI_PATH = "ilxe_lab/hello_world";
      HelloWorld.prototype.isPublic = true;

      /**
      * handle onGet HTTP request
      */
      HelloWorld.prototype.onGet = function(restOperation) {
        if (DEBUG === true) {
          logger.info("DEBUG: HelloWorld - onGet request");
        }
        restOperation.setBody(JSON.stringify(DEFAULT_MSG));
        this.completeRestOperation(restOperation);
      };

      /**
      *handle onPost HTTP request
      */
      HelloWorld.prototype.onPost = function(restOperation) {
        //we retrieve the payload sent with the POST request
       var newState = restOperation.getBody();

       if (DEBUG === true) {
          logger.info("DEBUG: HelloWorld - onPost received Body is: " + JSON.stringify(newState,' ','\t'));
        }
        //we extract the variable name from the payload
        var name = newState.name;

        //if it's empty, we just print Hello World, otherwise Hello <name>
        if (name) {
          if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onPost request, the extracted name is : " + name);
          }
          restOperation.setBody(JSON.stringify({ "value": "Hello " + name + "!"}));
        } else {
          if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onPost request, no name parameter provided... using default value");
          }
          restOperation.setBody(JSON.stringify(DEFAULT_MSG));
        }
        this.completeRestOperation(restOperation);
      };

      /**
      * handle /example HTTP request
      */
      HelloWorld.prototype.getExampleState = function () {
        return {
          "value": "your_string"
        };
      };

      module.exports = HelloWorld;

   * The lines starting with ``//`` are comments. It's always good to comment your code to help people read/understand your code... the
     more code there is, the more important it is to provide properly commented
     code.
   * ``var newState = restOperation.getBody();`` With this statement we
     retrieve the PAYLOAD that was sent in the POST request and we show this
     payload in the following logger command.
   * ``var name = newState.name;`` With this statement we assign the name parameter's
     value (sent with the POST request) to the name variable.
   * The following if/else statement determines whether the variable name is
     empty or not (if the POST payload didn't contain a name parameter) and
     depending on this will do the following:

     - If the variable name is not empty: reply to the ``POST`` request with
       Hello and the name of the user
     - If the variable name is empty: reply to the ``POST`` request with
       ``Hello World!``

#. Make sure you save your updated file.

#. Time to test our code!  Open another SSH session to the BIG-IP and run the following command:

   ``bigstart restart restnoded ; tail -f /var/log/restnoded/restnoded.log``

#. Review the logs to make sure there aren't any errors or issues with
   your updated file.

   .. NOTE::

    Keep this SSH session open to monitor your logs.
    It's easier to have one window for logs and a separate one for issuing commands. 

#. You should have something like this:

   .. code::

      Tue, 17 Oct 2017 13:11:19 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld
      Tue, 17 Oct 2017 13:11:19 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs
      Tue, 17 Oct 2017 13:11:19 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs/hello_world.js
      Tue, 17 Oct 2017 13:11:19 GMT - config: [RestWorker] /ilxe_lab/hello_world has started. Name:HelloWorld

#. You can now test your updated extension with the following commands:

   ``curl -k -u admin:admin https://10.1.1.245/mgmt/ilxe_lab/hello_world``

   The console output should look like this:

   ``{"value":"Hello World!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   ``Tue, 17 Oct 2017 13:33:45 GMT - info: DEBUG: HelloWorld - onGet request``

#. Run this command:

   ``curl -H "Content-Type: application/json" -k -u admin:admin -X POST -d '{"name":"iControl LX Lab"}' https://10.1.1.245/mgmt/ilxe_lab/hello_world``

#. The console output should look like this:

   ``{"value":"Hello iControl LX Lab!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   .. code::

      Tue, 17 Oct 2017 13:36:46 GMT - info: DEBUG: HelloWorld - onPost received Body is: {
      "name": "iControl LX Lab"
      }
      Tue, 17 Oct 2017 13:36:46 GMT - info: DEBUG: HelloWorld - onPost request, the extracted name is : iControl LX Lab

#. Run this command:

   ``curl -H "Content-Type: application/json" -k -u admin:admin -X POST -d '{"other":"iControl LX Lab"}' https://10.1.1.245/mgmt/ilxe_lab/hello_world``

#. The console output should look like this (the name parameter wasn't found in
   the POST payload):

   ``{"value":"Hello World!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   .. code::

      Tue, 17 Oct 2017 13:38:24 GMT - info: DEBUG: HelloWorld - onPost received Body is: {
      "other": "iControl LX Lab"
      }
      Tue, 17 Oct 2017 13:38:24 GMT - info: DEBUG: HelloWorld - onPost request, no name parameter provided... using default value

We now have an iControl LX Extension that is able to handle ``GET`` and ``POST``
requests as well as provide debugging information.

Task 2 - Update our iControl LX Extension - Perform a REST API Call
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Right now, our iControl LX Extension provides a default message that is set at
the beginning of our code. If this "content" is owned by someone else, it may
be inefficient to have it directly in the code. Let's see how we could leverage
an HTTP request to retrieve our default message.

For this task, we will do 3 things:

* Add the ``http`` module to our extension
* Add a new prototype ``onStart`` to our code
* Perform an HTTP request to GitHub to retrieve our default message

Perform the following steps to complete this task:

#. To add the http module to our extension, we'll need to add a bit of code. If your text editor has been closed, please reopen it. Below the line ``var DEFAULT_MSG = {"value": "Hello World!"};``

   add the following code:

   .. code-block:: javascript

      var http = require('http');

#. The prototype ``onStart`` is something you can leverage to do some
   processing when your iControl LX Extension is loaded in ``restnoded``. It
   is triggered only once, when your extension is loaded. It's a good prototype
   to leverage to retrieve our default message.

#. Under the line ``HelloWorld.prototype.isPublic = true;`` add the following
   code:

   .. code-block:: javascript

      /**
       * Perform worker start functions
       */

      HelloWorld.prototype.onStart = function(success, error) {

      if (DEBUG === true) {
        logger.info("DEBUG: HelloWorld - onStart request");
      }

      var options = {
        "method": "GET",
        "hostname": "s3-eu-west-1.amazonaws.com",
        "port": 80,
        "path": "/nicolas-labs/helloworld_resp.json",
        "headers": {
          "cache-control": "no-cache"
        }
      };

      var req = http.request(options, function (res) {

        var chunks = [];

        res.on("data", function (chunk) {
          chunks.push(chunk);
        });

        res.on("end", function () {
          var body = Buffer.concat(chunks);
          if (DEBUG === true) {
            logger.info("DEBUG: HelloWorld - onStart - the default message body is: " + body);
          }
          DEFAULT_MSG = JSON.parse(body);
        });
      });

      req.end();

      if (DEBUG === true) {
        logger.info("DEBUG: HelloWorld - onStart - the default message is: " + this.state);
      }
      success();
      };

#. The purpose of this code is to retrieve the file
   `helloworld_resp <http://s3-eu-west-1.amazonaws.com/nicolas-labs/helloworld_resp.json>`_. This file will give us the default payload we should return when we receive a request.

#. Make sure you save your updated code. Then run the following
   command:

   ``bigstart restart restnoded ; tail -f /var/log/restnoded/restnoded.log``

#. Review the logs to make sure there aren't any errors or issues with
   your updated file.

   You should have something like this:

   .. code::

      Wed, 18 Oct 2017 09:30:08 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs
      Wed, 18 Oct 2017 09:30:08 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs/hello_world.js
      Wed, 18 Oct 2017 09:30:08 GMT - info: DEBUG: HelloWorld - onStart request
      Wed, 18 Oct 2017 09:30:08 GMT - config: [RestWorker] /ilxe_lab/hello_world has started. Name:HelloWorld
      Wed, 18 Oct 2017 09:30:08 GMT - info: DEBUG: HelloWorld - onStart - the default message body is: { "value": "Congratulations on your lab!" }

#. You can now test your updated extension with the following command:

   ``curl -k -u admin:admin https://10.1.1.245/mgmt/ilxe_lab/hello_world``

#. The console output should look like this:

   ``{"value":"Congratulations on your lab!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   ``Tue, 17 Oct 2017 13:33:45 GMT - info: DEBUG: HelloWorld - onGet request``

#. Run this command:

   ``curl -H "Content-Type: application/json" -k -u admin:admin -X POST -d '{"name":"iControl LX Lab"}' https://10.1.1.245/mgmt/ilxe_lab/hello_world``

#. The console output should look like this:

   ``{"value":"Hello iControl LX Lab!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   .. code::

      Wed, 18 Oct 2017 09:32:40 GMT - info: DEBUG: HelloWorld - onPost received Body is: {
      "name": "iControl LX Lab"
      }
      Wed, 18 Oct 2017 09:32:40 GMT - info: DEBUG: HelloWorld - onPost request, the extracted name is : iControl LX Lab

#. Run this command:

   ``curl -H "Content-Type: application/json" -k -u admin:admin -X POST -d '{"other":"iControl LX Lab"}' https://10.1.1.245/mgmt/ilxe_lab/hello_world``

#. The console output should look like this (the name parameter wasn't found in
   the ``POST`` payload):

   ``{"value":"Congratulations on your lab!"}``

#. The ``/var/log/restnoded/restnoded.log`` output should look like this:

   .. code::

      Wed, 18 Oct 2017 09:33:38 GMT - info: DEBUG: HelloWorld - onPost received Body is: {
      "other": "iControl LX Lab"
      }
      Wed, 18 Oct 2017 09:33:38 GMT - info: DEBUG: HelloWorld - onPost request, no name parameter provided... using default value

Task 3 - Take a 5 minute break!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Congratulations!!!! You've just modified the behavior of the F5 iControl LX
Extension. Now take a moment to think about what workflows you could implement
to make life easier.