CS 61 Docker

The Docker container-based virtualization service lets you run a minimal CS 61 environment, including Linux, on a Mac OS X or Windows computer, without the overhead of a full virtual machine like VMware Workstation, VMware Fusion, or VirtualBox.

It should be possible to do all CS 61 problem sets on CS 61 Docker.

Advantages of Docker:

• Docker can start and stop virtual machines incredibly quickly.
• Docker-based virtual machines are small and occupy little space on your machine.
• With Docker, you can easily edit your code in your home environment, but compile and run it on a Linux host.

Disadvantages of Docker:

• Docker does not offer a graphical environment. You will need to run all CS 61 programs exclusively in the terminal.
• Docker technology is less user-friendly than virtual machines. You’ll have to type weird commands.
• You won’t get the fun, different feeling of a graphical Linux desktop.

Creating CS 61 Docker

1. Download and install Docker.

2. Clone the cs61-psets repository onto your computer.

3. Change into the cs61-psets/docker directory.

4. Run this command. It will take a while—up to ten minutes.

   $ ./cs61-build-docker

   The command starts up a virtual Linux-based computer running inside your computer. It then installs a bunch of software useful for CS 61 on that environment, then takes a snapshot of the running environment. (The snapshot has a name, such as cs61:latest or cs61:arm64.) Once the snapshot is created, it’ll take just a second or so for Docker to restart it.

We may need to change the Docker image during the term. If we do, you’ll update your repository to get the latest Dockerfile, then re-run the ./cs61-build-docker command from Step 4. However, later runs should be faster since they’ll take advantage of your previous work.

./cs61-build-docker is a wrapper around docker build. On x86-64 hosts, it runs docker build -t cs61:latest -f Dockerfile --platform linux/amd64 . {.note}

Running CS 61 Docker by script

Our handout repositories, including cs61-lectures and cs61-psets, contain a cs61-run-docker script that provides good arguments and boots Docker into a view of the current directory. We will update this script throughout the term.

For example, here’s an example of running CS 61 Docker on a Mac OS X host. At first, uname (a program that prints the name of the currently running operating system) reports Darwin. But after ./cs61-run-docker connects the terminal to a Linux virtual machine, uname reports Linux. At the end of the example, exit quits the Docker environment and returns the terminal to Mac OS X.

$ cd ~/cs61-lectures
$ uname
Darwin
$ uname -a
Darwin Eddies-MacBook-Pro.local 20.6.0 Darwin Kernel Version 20.6.0: Wed Jun 23 00:26:27 PDT 2021; root:xnu-7195.141.2~5/RELEASE_ARM64_T8101 arm64
$ ./cs61-run-docker
cs61-user@a47f05ea5085:~/cs61-lectures$ uname
Linux
cs61-user@a47f05ea5085:~/cs61-lectures$ uname -a
Linux a47f05ea5085 5.10.47-linuxkit #1 SMP PREEMPT Sat Jul 3 21:50:16 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
cs61-user@a47f05ea5085:~/cs61-lectures$ ls
common  cs61-run-docker  docker  README.md
cs61-user@a47f05ea5085:~/cs61-lectures$ exit
exit
$ 

A prompt like cs61-user@a47f05ea5085:~$ means that your terminal is connected to the VM. (The a47f05ea5085 part is a unique identifier for this running VM.) You can execute any Linux commands you want. To escape from the VM, type Control-D or run the exit command.

The script assumes your Docker container is named cs61:latest or cs61:arm64.

Running CS 61 Docker by hand

If you don’t want to use the script, use a command like the following.

$ docker run -it --platform linux/amd64 --rm -v ~/cs61-lectures:/home/cs61-user/cs61-lectures cs61:latest

Explanation:

• docker run tells Docker to start a new virtual machine.
• -it says Docker should run interactively (-i) using a terminal (-t).
• --platform linux/amd64 says Docker should emulate an x86-64-based machine. It’s necessary to specify this if you have (for example) an Apple M1-based laptop.
• --rm says Docker should remove the virtual machine when it is done.
• -v LOCALDIR:LINUXDUR says Docker should share a directory between your host and the Docker virtual machine. Here, I’ve asked for the host’s ~/cs61-lectures directory to be mapped inside the virtual machine onto the /home/cs61-user/cs61-lectures directory, which is the virtual machine user’s ~/cs61-lectures directory.
• cs61:latest names the Docker image to run (namely, the one you built).

Here’s an example session:

$ docker run -it --platform linux/amd64 --rm -v ~/cs61-psets:/home/cs61-user/cs61-psets cs61:latest
cs61-user@a15e6c4c8dbe:~$ ls
cs61-psets
cs61-user@a15e6c4c8dbe:~$ echo "Hello, world"
Hello, world
cs61-user@a15e6c4c8dbe:~$ cs61-docker-version
16
cs61-user@a15e6c4c8dbe:~$ exit
exit
$