Setup AutoLab

4 minute read

In an effort to improve efficiency and to provide more detailed feedback to student, we are looking into implementation and deployment of autograders. In this post, I describe the process of configuring and deploying a test instance of Carnegie Mellon University’s Autolab.

The target operating system is Ubuntu 18.04. Initially, I tried Autolab’s OneClick option. However, there are various errors happened along the way, and using OneClick doesn’t help with the debugging process. In the end, I decided to follow the manual installation guide.

Installing AutoLab

The following commands are embedded in Autolab’s script. However, with Ubuntu 18.04, it is better to manually run these commands so that you have more control over what is being done.

 $ sudo apt-get -y -qq update
 $ sudo apt-get -y -qq upgrade
 $ sudo apt-get -y install aptitude
 $ sudo aptitude -y install build-essential git libffi-dev zlib1g-dev autoconf bison libssl1.0-dev libyaml-dev libreadline6-dev libncurses5-dev libgdbm5 libgdbm-dev libmysqlclient-dev curl

Note: Comparing to the original script, libssl-dev is changed to libssl1.0-dev, and libgdbm3 is changed to libgdbm5. To help with the potential dependency issues, I used aptitude instead of apt-get.

In the original documentation, we have

$ AUTOLAB_SCRIPT=`mktemp` && \curl -sSL > $AUTOLAB_SCRIPT && \bash $AUTOLAB_SCRIPT

We will need to make several changes the script. We start by running:

$ AUTOLAB_SCRIPT=`mktemp` && \curl -sSL > $AUTOLAB_SCRIPT

Next, run


Comment out line 105. Also, on lines 138, inside ruby_setup(), insert

echo "2.3.0" > $AUTOLAB_PATH/.ruby-version

After save and quit from vim, run:


After the successful installation of Autolab, you will receive the following messages:

Autolab installation is now complete. When you start a new login-shell, you may run the following command to start up Autolab server at Port 3000:
                         cd ~/Autolab && bundle exec rails s -p 3000 --binding=

Top things to do after installation:

- Try out Tango (, the back-end service for Autolab, and fill in relevant parameters in ./config/autogradeConfig.rb
- Sign up for our mailing list to learn about new features and bug fixes:
- Change MySQL root password (the password we generated is not strong enough for serious use.)
- Change MySQL password for `lngo`, and update it in ./config/database.yml (default password is '<password>')
- Contact us if you have any questions!

Thank you for trying out Autolab! For questions and comments, email us at

As a final reminder, your MySQL root password is: OTE4YjcwZjQ2MTA3YjU2Y2UyNTdlMTE5.

Let’s hold off on starting Autolab until a bit later.

Installing Tango

Install and run Redis:

$ cd ~
$ wget
$ tar xvzf redis-stable.tar.gz
$ cd redis-stable
$ make
$ sudo aptitude install tcl tk
$ make test
$ sudo make install
$ redis-server --daemonize yes

Install and run Docker

$ sudo aptitude install -y apt-transport-https ca-certificates curl software-properties-common
$ curl -fsSL | sudo apt-key add -
$ sudo add-apt-repository "deb [arch=amd64] $(lsb_release -cs) stable"
$ sudo apt-get update
$ sudo apt-get install -y docker-ce
$ sudo usermod -aG docker $USER

At this point, log out and log backin to enable group modification so that the user account can runs docker (See Linux Postintallation).

Next, we clone Tango and create the default configuration file.

$ git clone
$ cd Tango
$ cp
$ mkdir courselabs

We will use Docker to build a default autograder VM for Tango:

$ cd path/to/Tango
$ docker build -t autograding_image vmms/
$ docker images autograding_image    # Check if image built

Confirm that the VMMS_NAME option in is set to localDocker as follows:

# in
VMMS_NAME = "localDocker"

Next, we setup the Python virtual environment for Tango.

$ sudo aptitude install virtualenv
$ virtualenv .
$ source bin/activate
$ pip install -r requirements.txt
$ mkdir volumes

Run the following command to start the server (producer). If no port is given, the server will run on the port specified in (default: 3000):

$ python restful-tango/ <port>

Open another terminal window and start the job manager (consumer):

$ cd Tango
$ source bin/activate
$ python

In yet another terminal, you can test that Tango is running:

$ curl localhost:<port>
# Hello, world! RESTful Tango here!

Running Autolab.

Now you can configure Autolab to use Tango. Go to your Autolab directory and enter the following commands:

$ cp config/autogradeConfig.rb.template config/autogradeConfig.rb

You can edit the autogradeConfig.rb file so that it points to your Tango deployment. In this case, we are hosting Tango in the same location as the Autolab web server.

# Hostname for Tango RESTful API
RESTFUL_HOST = "localhost"

# Port for Tango RESTful API

# Key for Tango RESTful API
RESTFUL_KEY = "test"

Now you can start Autolab:

$ cd ~/Autolab && bundle exec rails s -p 3000 --binding=

If your host machine has a public IP address, you can open a browser and visit :3000. Otherwise, you can open an internal browser on your machine and visit `localhost:3000`. The login and password are and *adminfoobar*.