Single Call Security iControl LX REST API Lab > Class 1 - Single Call Security iControl LX REST API Lab > Module 4 - Installing the HelloWorld extension Source | Edit on

Lab 4.1 - Creating the HelloWorld iControl LX Extension¶

iControl LX Extensions are distributed as RPMs (RedHat Package Management system) when you want to leverage something existing. However when you start from scratch, you’ll need to create your extension and then build a RPM that you can distribute accordingly.

Task 1 - Create our iControl LX Extension on BIG-IP¶

iControl LX Extensions can be installed on either the BIG-IP or iWorkflow platform. For this lab, we will use BIG-IP.

Perform the following steps to complete this task:

Connect to your BIG-IP via SSH/PuTTY(10.1.1.245).
iControl LX Extensions reside in /var/config/rest/iapps/. This is where you need to create your iControl LX Extension. Usually you will create:
- A folder that is the name of your app: HelloWorld
Note

This folder name is important since this is what will be used as the RPM name when we will create our package later.
- Inside the app folder, another folder called nodejs that will contain your extension
Let’s create our directory tree. On your BIG-IP execute the following:

mkdir -p /var/config/rest/iapps/HelloWorld/nodejs/
Now that we have our directory, we need to create our extension. Use your preferred text editor and create a file named hello_world.js in /var/config/rest/iapps/HelloWorld/nodejs/:

For example, using nano the command would be nano /var/config/rest/iapps/HelloWorld/nodejs/hello_world.js

Note

If you have not used nano before: After you paste in the contents below, you will type CTRL-X to exit the editor. You will then be prompted to save the file, type Y to confirm.

Copy/Paste the following content into your file:

/**
* A simple iControl LX Extension that handles only HTTP GET
*/
function HelloWorld() {}

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

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

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

module.exports = HelloWorld;

Save the changes (CTRL-X, Y if you use nano, ESC ESC :wq if you use vi).
Once our extension is created, we need to load it into restnoded. When an extension is loaded from an RPM, it is done automatically. However in this case we will need to do it ourselves.

Use the following command on the BIG-IP to make restnoded aware of our extension:

restcurl shared/nodejs/loader-path-config -d '{"workerPath": "/var/config/rest/iapps/HelloWorld"}'

Note

restcurl is a utility that allows you to communicate with iControl REST via the CLI.

The output should look like this:
```
$ restcurl shared/nodejs/loader-path-config -d '{"workerPath": "/var/config/rest/iapps/HelloWorld"}'
{
  "id": "ad130c79-59a0-49c7-a7e7-ff39efe956b5",
  "workerPath": "/var/config/rest/iapps/HelloWorld",
  "generation": 1,
  "lastUpdateMicros": 1508242306312732,
  "kind": "shared:nodejs:loader-path-config:loaderpathstate",
  "selfLink": "https://localhost/mgmt/shared/nodejs/loader-path-config/ad130c79-59a0-49c7-a7e7-ff39efe956b5"
}
```

The logfile /var/log/restnoded/restnoded.0.log will give you the ability to track whether your extension is loaded as expected. Run the following command to ensure everything went smoothly:

grep HelloWorld /var/log/restnoded/restnoded.log

The output should look like this:

Tue, 17 Oct 2017 12:11:46 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld
Tue, 17 Oct 2017 12:11:46 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs
Tue, 17 Oct 2017 12:11:46 GMT - finest: [LoaderWorker] triggered at path:  /var/config/rest/iapps/HelloWorld/nodejs/hello_world.js
Tue, 17 Oct 2017 12:11:46 GMT - config: [RestWorker] /ilxe_lab/hello_world has started. Name:HelloWorld

Task 2 - Check our iControl LX Extension is Working¶

Perform the following steps to complete this task:

In your web browser, navigate to https://10.1.1.245/mgmt/ilxe_lab/hello_world.
You should see something like this:
You could also use curl from a command line (from the BIG-IP CLI for example):

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

Or a REST client like Postman.
Another test is to connect to our /example uri. Navigate with your browser to https://10.1.1.245/mgmt/ilxe_lab/hello_world/example.
You should see something like this:
You can use curl from a command line for this as well:

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

Note

You may not want to use admin privileges to leverage an extension. In many situations an extension may only be needed by specific users, in which case you would be able to enforce RBAC (Role-Based Access Control) policies. BIG-IP version 13.1 and later provides this capability.

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