Docker Fun – Locomotive

trainWelcome to the second in my series of using Docker in some fun and unusual ways. In the first installment, I showed how to display a Matrix screen similar to the movie. This time, we’ll look at showing a steam locomotive engine in motion in a Docker container. I’m not sure where this application originated, but it seems to have started as an Easter Egg in Linux to tweak people who misspell the system command ‘ls’.

Like last month’s this is an easy container to implement, consisting of only a three line Dockerfile.

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Using Docker on demand with Linux Mint

container_shippingIf you are like me and work on multiple things on your development system, you don’t always want everything running when you start your PC. I’ve previously covered starting other services on demand, and this time around I’ll cover running Docker as needed.

Docker has essentially two separate components. There is the Docker daemon (or service) that is configured to start when the system is booted up and there is the Docker CLI that you interact with and your commands are passed to the daemon. The CLI only runs when you specifically call it from the terminal prompt with the DOCKER command. For my purposes, I didn’t need or want the daemon running all the time because its a laptop. (If I was using a production system or even a full blown development box, I would prefer to have the daemon always running.) So after installing Docker, I needed to configure it to not start up every time the system starts, and then come up with an easy way to start it as needed. Continue reading

Cannot connect to the Docker daemon – fixed!

containersA quick note this time around: After installing Docker on my Linux Mint laptop, I wanted to be able to run it with my normal user account and not have to SUDO every time I wanted to start a container. (Please be advised that doing so can be considered a HUGE security hole, but since I am just testing Docker, I was willing to risk it).

In order to do this, all of the documentation I found said to create a Docker group, and then add my user account to that group, and restart. This is fairly simple to accomplish with the GUI Users and Groups tool. The Docker daemon then uses that group to see if the user account has permissions to start Docker and connect to the daemon. The result? I would get this error: Cannot connect to the Docker daemon. Is ‘docker daemon’ running on this hostAfter trying several things, I finally found the solution.

  1. From a terminal prompt run this command:
    echo $DOCKER_HOST

    You should see a line indicating your Docker host is set to an IP address. You will need to clear it.

  2. At the terminal prompt, switch  to your home folder:
    cd ~
  3. Now, edit your shell profile:
     nano ./.profile
  4. Look for a line like this:
     export DOCKER_HOST=tcp://
  5. Add a comment marker (#) before it or delete the line completely. Save your profile file and exit.
  6. Restart your system, and you should now be able to run Docker using your normal user account.



Install the Tor Browser on Linux

DCF 1.0

The TOR project was started by United States Naval Research Lab employees in the early part of the 21st century as a way to protect intelligence communications  online. It was open sourced in 2004, and continues to be supported by the Electronic Frontier Foundation. As privacy as continued to decline on the Internet, interest in the Tor Browser and Tor project has increased. For more information on TOR see this recent article at

I would like to note that I don’t support or condone the use of TOR for illicit or illegal purposes, but for those who feel that their privacy is important , I am providing these instructions for how to install the Tor Browser on Linux. These instructions should work for most Linux distros.

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