Labtainers in a Web desktop through noVNC X11 proxy, full docker containers

Here’s another recording of a demo I’ve made of our efforts on running Labtainers with a Web desktop.

This time, we’re using a modified version of DoroWu’s noVNC X11 wrapper container (“docker-ubuntu-vnc-desktop“), to provide an X11 Display to labtainers.

I initially adapted DoroWu’s container image by using Debian instead of Ubuntu, but it appeared that noVNC 1.0.0 was a bit too old in the Debian package. So I switched back to the same version as the one DoroWu chose, and this time no more disconnections.

Also, we’re now rebuilding the Labtainer master container from upstream’s Git repo. Fresh Labs every day 😉

Continue reading “Labtainers in a Web desktop through noVNC X11 proxy, full docker containers”

Two demos of programming inside the Web browser with Theia for Java and PHP, using Docker

Theia is a Web IDE that can be used to offer a development environment displayed in a Web browser.

I’ve recorded 2 screencasts of running Theia inside Docker containers, to develop Java and PHP applications, respectively using Maven and Composer (the latter is a Symfony application).
Continue reading “Two demos of programming inside the Web browser with Theia for Java and PHP, using Docker”

Demo of displaying labtainers labs in a Web browser through Guacamole

Here’s a first report on trying to add Guacamole to Labtainers in order to allow running Labtainers in a headless way, without an X display, in containers, and accessing the GUI in a Web browser, through the use of VNC and Guacamole.

We’ve casted a demo of it :

Labtainer + Guacamole demo on Vimeo.

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Virtualized lab demonstration using a tweaked Labtainers running in a container

I’ve recorded a screencast: Labtainers in docker demonstration (embedded below) demonstrating how I’ve tweaked Labtainers so as to run it inside its own Docker container.

I’m currently very much excited by the Labtainers framework for delivering virtual labs, for instance in the context of MOOCs.

Labtainers is quite interesting as it allows isolating a lab in several containers running in their own dedicated virtual network, which helps distributing a lab without needing to install anything locally.

My tweak allows to run what I called the “master” container which contains the labtainers scripts, instead of having to install labtainers on a Linux host. This should help installation and distribution of labtainers, as well as deploying it on cloud platforms, some day soon. In the meantime Labtainer containers of the labs run with privileges so it’s advised to be careful, and running the whole of these containers in a VM may be safer. Maybe Labtainers will evolve in the future to integrate a containerization of its scripts. My patches are pending, but the upstream authors are currently focused on some other priorities.

Another interesting property of labtainers that is shown in the demo is the auto-grading feature that uses traces of what was performed inside the lab environment by the student, to evaluate the activities. Here, the telnetlab that I’ve shown, is evaluated by looking at text input on the command line or messages appearing on the stdout or in logs : the student launched both telnet or ssh, some failed login appeared, etc.

However, the demo is a bit confusing, in that I recorded a second lab execution whereas I had previously attempted a first try at the same telnetlab. In labtainers, traces of execution can accumulate : the student wil make a first attempt, and restart later, before sending it all to the professor (unless a redo.py is issued). This explanes that the  grading appears to give a different result than what I performed in the screencast.

Stay tuned for more news about my Labtainers adventures.

P.S. thanks to labtainers authors, and obs-studio folks for the screencast recording tool 🙂

Implementing an example Todo-Backend REST API with Symfony 4 and api-platform

Todo-Backend lists many implementations of the same REST API with different backend-oriented Web development frameworks.

I’ve proposed my own version using Symfony 4 in PHP, and the api-platform project which helps implementing REST APIs.

I’ve documented the way I did it in the project’s documentation in details, for those curious about Symfony development of a very simple REST API (JSON based). See its README file (of course redacted with the mandatory org-mode ;).

You can find the rest of the code here : https://gitlab.com/olberger/todobackend-symfony4.

AFAICS api-platform offers a great set of features for Linked-Data/REST development with Symfony in general. However, some tweaks were necessary to conform the TodoBackend specs, mainly because TodoBackend is JSON only and doesn’t support JSON-LD…

Oh, and the hardest part was deploying on Heroku, making sure that the CORS headers would work as expected :-/