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Autolab + Tango Docker Compose Installation

The Autolab Docker Compose installation is a fast and easy production-ready installation and deployment method. It uses a MySQL database for the Autolab deployment, and comes with TLS/SSL support. This is now the preferred way of installing Autolab.

If you are stuck or find issues with the installation process you can either file an issue on our Github repository, or join our Slack here and let us know and we will try our best to help. Also see the debugging section for tips on how to diagnose problems and check out the troubleshooting section if you run into any issues.


First ensure that you have Docker and Docker Compose installed on your machine. See the official Docker docs for the installation steps.

  1. Clone this repository and its Autolab and Tango submodules:

    git clone --recurse-submodules -j8 git:// autolab-docker
  2. Enter the project directory:

    cd autolab-docker
  3. Update our Autolab and Tango submodules to ensure that you are getting the latest versions:

    make update
  4. Create initial default configs:

  5. Build the Dockerfiles for both Autolab and Tango:

    docker-compose build
  6. Run the Docker containers:

    docker-compose up -d

    Note at this point Nginx will still be crash-looping in the Autolab container because TLS/SSL has not been configuired/disabled yet.

  7. Ensure that the newly created config files have the right permissions, as it may have been modified during the building process:

    make set-perms
  8. Perform database migrations for Autolab, which will initialize your database schema:

    make db-migrate
  9. Create administrative user for Autolab:

    make create-user

    This user has full permissions on Autolab and will be able to create other users and designate other admins.

  10. Change DOCKER_TANGO_HOST_VOLUME_PATH in docker-compose.yml to be the absolute path to the Tango volumes directory, i.e /<path-to-docker-compose-installation>/Tango/volumes. This is so that Tango knows where to put the output files of its autograded jobs.

    # in docker-compose.yml
    # Modify the below to be the path to volumes on your host machine
    - DOCKER_TANGO_HOST_VOLUME_PATH=/home/your-user/autolab-docker/Tango/volumes # example path
  11. Stop all containers, as we are going to setup/disable TLS:

    docker-compose stop
  12. If you intend to use TLS later, in nginx/app.conf, change instances of <REPLACE_WITH_YOUR_DOMAIN> to your real domain name. Otherwise, if you are not using TLS, in nginx/no-ssl-app.conf, change server_name to your real domain name.

  13. Continue with TLS setup as outlined in the next section

  14. Build the autograding image(s) that you want to use in Tango (see the docs for more information). For this setup we will stick to the default Ubuntu 18.04 autograding image:
    docker build -t autograding_image Tango/vmms/

Note that we can just run this directly on the host because we are mapping the Docker socket to the Tango container (i.e they are using the same Docker server).

  1. Start up everything:
    docker-compose up -d

Autolab should now be accessible on port 80 (and 443 if you configured TLS)!

Configuring TLS/SSL

Having TLS/SSL configured is important as it helps to ensure that sensitive information like user credentials and submission information are encrypted instead of being sent over in plaintext across the network when users are using Autolab. We have made setting up TLS as easy and pain-free as possible. Using TLS is strongly recommended if you are using Autolab in a production environment with real students and instructors.

There are three options for TLS: using Let's Encrypt (for free TLS certificates), using your own certificate, and not using TLS (suitable for local testing/development, but not recommended for production deployment).

Option 1: Let's Encrypt

  1. Ensure that your DNS record points towards the IP address of your server
  2. Ensure that port 443 is exposed on your server (i.e checking your firewall, AWS security group settings, etc)
  3. Get initial SSL setup script: make ssl
  4. In ssl/, change domains=( to the list of domains that your host is associated with, and change email to be your email address so that Let's Encrypt will be able to email you when your certificate is about to expire
  5. If necessary, change staging=0 to staging=1 to avoid being rate-limited by Let's Encrypt since there is a limit of 20 certificates/week. Setting this is helpful if you have an experimental setup.
  6. Run your modified script: sudo sh ./ssl/

Option 2: Using your own TLS certificate

  1. Copy your private key to ssl/privkey.pem
  2. Copy your certificate to ssl/fullchain.pem
  3. Generate your dhparams:

    openssl dhparam -out ssl/ssl-dhparams.pem 4096
  4. Uncomment the following lines in docker-compose.yml:

    # - ./ssl/fullchain.pem:/etc/letsencrypt/live/;
    # - ./ssl/privkey.pem:/etc/letsencrypt/live/;
    # - ./ssl/ssl-dhparams.pem:/etc/letsencrypt/ssl-dhparams.pem
  1. In docker-compose.yml (for all the subsequent steps), comment out the following:

    # Comment the below out to disable SSL (not recommended)
    - ./nginx/app.conf:/etc/nginx/sites-enabled/webapp.conf

    Also uncomment the following:

    # Uncomment the below to disable SSL (not recommended)
    # - ./nginx/no-ssl-app.conf:/etc/nginx/sites-enabled/webapp.conf

    Lastly set DOCKER_SSL=false:

    - DOCKER_SSL=true                         # set to false for no SSL (not recommended)

Updating Your Docker Compose Deployment

  1. Stop your running instances:

    docker-compose stop
  2. Update your Autolab and Tango repositories:

    make update
  3. Rebuild the images with the latest code:

    docker-compose build
  4. Re-deploy your containers:

    docker-compose up

Debugging your Deployment

In the (very likely) event that you run into problems during setup, hopefully these steps will help you to help identify and diagnose the issue. If you continue to face difficulties or believe you discovered issues with the setup process please join our Slack here and let us know and we will try our best to help.

Better logging output for Docker Compose

By default, docker-compose up -d runs in detached state and it is not easy to immediately see errors:

$ docker-compose up -d
Starting certbot ... done
Starting redis   ... done
Starting mysql   ... done
Starting tango     ... done
Recreating autolab ... done

Use docker-compose up instead to get output from all the containers in real time:

$ docker-compose up
Starting certbot ... done
Starting mysql   ... done
Starting redis   ... done
Starting tango   ... done
Starting autolab ... done
Attaching to redis, mysql, certbot, tango, autolab
mysql      | [Entrypoint] MySQL Docker Image 8.0.22-1.1.18
tango      | 2020-11-11 04:33:19,533 CRIT Supervisor running as root (no user in config file)
redis      | 1:C 11 Nov 2020 04:33:19.032 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
redis      | 1:C 11 Nov 2020 04:33:19.032 # Redis version=6.0.9, bits=64, commit=00000000, modified=0, pid=1, just started
redis      | 1:C 11 Nov 2020 04:33:19.032 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
mysql      | [Entrypoint] Starting MySQL 8.0.22-1.1.18
redis      | 1:M 11 Nov 2020 04:33:19.033 * Running mode=standalone, port=6379.
redis      | 1:M 11 Nov 2020 04:33:19.033 # Server initialized
tango      | 2020-11-11 04:33:19,539 INFO RPC interface 'supervisor' initialized
tango      | 2020-11-11 04:33:19,539 CRIT Server 'unix_http_server' running without any HTTP authentication checking
mysql      | 2020-11-11T04:33:19.476749Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.22) starting as process 22
--- output truncated ---

Checking Autolab logs

If the Autolab instance is not working properly, taking a look at both the application logs as well as the Nginx logs in the container will be helpful.

First, find the name of the container. This should be just autolab by default:

$ docker ps
CONTAINER ID        IMAGE                       COMMAND                  CREATED             STATUS                    PORTS                                      NAMES
765d35962f52        autolab-docker_autolab      "/sbin/my_init"          31 minutes ago      Up 22 minutes   >80/tcp,>443/tcp   autolab
a5b77b5267b1        autolab-docker_tango        "/usr/bin/supervisor…"   7 days ago          Up 22 minutes   >3000/tcp                     tango
438d8e9f73e2        redis:latest                "docker-entrypoint.s…"   7 days ago          Up 22 minutes             6379/tcp                                   redis
da86acc5a4c3        mysql/mysql-server:latest   "/ mysq…"   7 days ago          Up 22 minutes (healthy)   3306/tcp, 33060-33061/tcp                  mysql
88032e85d669        a2eb12050715                "/bin/bash"              9 days ago          Up 2 days                                                            compiler

Next get a shell inside the container:

$ docker exec -it autolab bash

By default we are in the project directory. Navigate to the logs directory and cat or tail production.log. This contains logs from the Autolab application itself.

root@be56be775428:/home/app/webapp# cd log
root@be56be775428:/home/app/webapp/log# tail -f -n +1 production.log

We can also check out our Nginx logs in /var/log/nginx/:

root@be56be775428:/home/app/webapp/log# cd /var/log/nginx/
root@be56be775428:/var/log/nginx# ls
access.log  error.log

Accessing the Rails console

Obtain a shell in the autolab container as described previously, and do RAILS_ENV=production bundle exec rails c:

root@be56be775428:/home/app/webapp# RAILS_ENV=production bundle exec rails c
Loading production environment (Rails 5.2.0)
2.6.6 :001 > User.all.count
=> 1

In the example above, if you performed make create-user you should have at least one user in your database. If there are errors connecting to a database here it is likely that the database was misconfigured.

Checking Tango Logs

Get a shell in the Tango instance, similar to the instructions mentioned previously. The logs are stored in the parent folder (/opt/TangoService) of the project directory:

$ docker exec -it tango bash
root@a5b77b5267b1:/opt/TangoService/Tango# cd ..
root@a5b77b5267b1:/opt/TangoService# ls
Tango  tango_job_manager_log.log  tango_log.log
root@a5b77b5267b1:/opt/TangoService# tail -f -n +1 tango_job_manager_log.log tango_log.log

Troubleshooting Autolab/Tango Connection

In the Autolab container, try to curl Tango:

root@be56be775428:/home/app/webapp# curl tango:3000
Hello, world! RESTful Tango here!

In the Tango container, try to curl Autolab:

root@a5b77b5267b1:/opt/TangoService/Tango# curl autolab
<head><title>301 Moved Permanently</title></head>
<body bgcolor="white">
<center><h1>301 Moved Permanently</h1></center>
<hr><center>nginx/1.14.0 (Ubuntu)</center>

Permission issues in Autolab

Run the following again:

make set-perms

Restarting Autolab Passenger Server

This is useful when you might want to test out some code change within the Autolab container without having to rebuild everything again. These changes can be applied by just restarting the Passenger service that is serving Autolab.

Run passenger-config restart-app:

root@8b56488b3fb6:/home/app/webapp# passenger-config restart-app
Please select the application to restart.
Tip: re-run this command with --help to learn how to automate it.
If the menu doesn't display correctly, press '!'

‣   /home/app/webapp (production)

Restarting /home/app/webapp (production)


If you obtain the following error when attempting to perform make update:

error: unable to unlink old 'db/schema.rb': Permission denied
fatal: Could not reset index file to revision 'HEAD'.

This is due to the fact that db/schema.rb is updated whenever migrations are performed. db/schema.rb documents the database schema, which depends on the database that you are using, its version, and when the migrations were run. It is likely that your db/schema.rb will diverge from the one generated by the devs.

You can resolve this by changing the owner of the files to be your current user, and then running make set-perms afterwards when you start the containers again.