The hastexo XBlock is an Open edX API that integrates realistic lab environments into distributed computing courses. The hastexo XBlock allows students to access an OpenStack environment within an edX course.

The hastexo XBlock orchestrates a virtual environment (a "stack") that runs on an OpenStack private or public cloud using the OpenStack Heat orchestration engine. It provides a Secure Shell session directly within the courseware.

Stack creation is idempotent, so a fresh stack will be spun up only if it does not already exist. An idle stack will auto-suspend after a configurable time period, which is two minutes by default. The stack will resume automatically when the student returns to the lab environment.

Since public cloud environments typically charge by the minute to run virtual machines, the hastexo XBlock makes lab environments cost effective to deploy. The hastexo XBlock can run a fully distributed virtual lab environment for a course in Ceph, OpenStack, Open vSwitch or fleet for approximately $25 per month on a public cloud (assuming students use the environment for 1 hour per day).

Course authors can fully define and customize the lab environment. It is only limited by the feature set of OpenStack Heat.

The easiest way for platform administrators to deploy the hastexo XBlock and its dependencies to an Open edX installation is to pip install it to the edxapp virtualenv, and then to use the gateone role included in hastexo's fork of edx/configuration.

To deploy the hastexo XBlock:

1. Install it via pip:

   $ sudo /edx/bin/pip.edxapp install -e git+https://github.com/hastexo/hastexo-xblock.git@master#egg=hastexo-xblock
   

2. Add it to the ADDL_INSTALLED_APPS of your LMS environment, by editing /edx/app/edxapp/lms.env.json and adding:

   "ADDL_INSTALLED_APPS": [
       "hastexo"
   ],
   

3. Now install gateone by cloning the hastexo fork of edx/configuration and assigning that role to the machine:

   $ git clone -b hastexo/master/base https://github.com/hastexo/edx-configuration.git
   $ cd edx-configuration/playbooks
   $ ansible-playbook -c local -i "localhost," run_role.yml -e role=gateone
   

4. Finally, restart edxapp and its workers:

   sudo /edx/bin/supervisorctl restart edxapp:
   sudo /edx/bin/supervisorctl restart edxapp_worker:
   

5. In your course, go to the advanced settings and add the hastexo module to the "Advanced Module List" like so:

   [
    "annotatable",
    "videoalpha",
    "openassessment",
    "hastexo"
   ]
   

To use the hastexo XBlock upload a Heat template to the content store. There are some limitations to the configuration of the Heat template (detailed below), but otherwise you can customize your training environment as you like. A sample template is provided under heat-templates/hot/openstack-sample.yaml.

To ensure your Heat template has the required configuration:

1. Upload a Heat template to the content store and make a note of its static asset file name.

2. Configure the Heat template to generate an SSH key pair dynamically and save the private key. For example:

   training_key:
     type: OS::Nova::KeyPair
     properties:
       name: { get_param: 'OS::stack_name' }
       save_private_key: true
   

3. Configure the Heat template to have an instance that is publicly accessible on the internet via floating_ip_address.

4. Provide the above two items as outputs, with the following names:

   outputs:
     public_ip:
       description: Floating IP address of deploy in public network
       value: { get_attr: [ deploy_floating_ip, floating_ip_address ] }
     private_key:
       description: Training private key
       value: { get_attr: [ training_key, private_key ] }
   

To create a stack for a student and display a terminal window where invoked, you need to define the hastexo tag in your course content with the following information:

• The credentials for the public or private OpenStack cloud
• The static asset path to markdown lab instructions
• The static asset path to a Heat template
• The name of the user that the Xblock will use to connect to the environment via SSH.

<vertical url_name="lab_introduction">
  <hastexo
    url_name="lab_introduction"
    instructions_path="markdown_lab.md"
    stack_template_path="hot_lab.yaml"
    stack_user_name="training"
    os_auth_url="https://os.auth.url:5000/v2.0"
    os_tenant_name="example.com"
    os_username="demo@example.com"
    os_password="foobarfoobarfoofoo" />
</vertical>

Important: Do this only once per section. Defining it more that once per section has undefined behavior.

In order to add the Hastexo Xblock through Studio, open the (sub)unit where you want it to appear. Add a new component and select Advanced, then select the Lab component. This adds the XBlock. Edit the Settings to add the various OpenStack variables.

When students navigate to a unit with a hastexo XBlock in it, a new Heat stack will be created (or resumed) for them. The Heat stack will be as defined in the uploaded Heat template. It is unique per student and per course run. If the same tag appears on a different course, or different run of the same course, the student will get a different stack.

The stack will suspend if the student does not navigate to the hastexo unit in that section within two minutes. When the student gets to the hastexo unit, the stack will be resumed and they will be connected automatically and securely. They will not need a username, password, or host prompts to their personal lab environment. This happens transparently in the browser.

The student can work at their own pace in their environment. However, when a student closes the browser where the hastexo unit is displayed, or if they put their computer to sleep, a countdown is started. If the student does not reopen the environment within two minutes their stack will be suspended. When a student comes back to the lab environment to finish the exercise, their stack is resumed automatically. They are connected to the same training environment they were working with before, in the same state they left it in.

For now, one must run the provided unit tests (which are currently limited to tasks) from the edxapp virtualenv, as deployed by fullstack. Thus, on such a box:

$ sudo /edx/bin/python.edxapp -m unittest hastexo.tests.unit.test_tasks

Or,

$ cd /edx/app/edxapp/hastexo-xblock
$ /edx/app/edxapp/venvs/edxapp/bin/nosetests hastexo/tests -v

This XBlock is licensed under the Affero GPL; see LICENSE for details.