dtloha.blogg.se - Docker run image in terminal

#DOCKER RUN IMAGE IN TERMINAL FOR MAC#
#DOCKER RUN IMAGE IN TERMINAL INSTALL#
#DOCKER RUN IMAGE IN TERMINAL FULL#

Docker for Mac runs a Linux virtual machine automatically, and containers are run in isolation inside of that VM. We can't access the parent environment, because our container is running in "isolation," which is the point of Docker. The Linux parent environment does run an init process, otherwise it wouldn't be running. While running Bash in a container, the "container" is actually an isolated environment in a hidden parent Linux Virtual Machine.

#DOCKER RUN IMAGE IN TERMINAL FULL#

So no, we aren't running a full Ubuntu operating system in the container. Is there something that looks like an initializing process here? Nope!

#DOCKER RUN IMAGE IN TERMINAL INSTALL#

Is Ubuntu running in the container? Meaning, is there an initializing program running inside the container? Let's check! In the container shell, install htop: apt-get update & apt-get install htop Now we're on a Bash shell inside an Ubuntu Docker container. Subsequent runs use your local image cache. This command will download the ubuntu image if you've never run it before.

Using -rm so the container will be removed automatically after we stop it.

Using the flags -it so our keystrokes get into the container.

Then, in the terminal, run: docker run -rm -it ubuntu bash If you're still running htop in your Mac's terminal, press ctrl-c to exit back to the shell. Make sure you have Docker for Mac installed first. Ok, so what's going on in a Docker container? To find out, let's run the same htop tool in an Ubuntu Docker container. It's different per operating system, and can also be changed by savvy users. On the server hosting this website, I see /sbin/init as the root process.

On your Mac, the initialization program is launchd. Key concept: All operating systems have some variation of a "kernel" and an " initialization program". It's responsible for setting up networking, and scheduling jobs and services the operating system needs. I think of launchd as the program that boots the operating system. Processes ending in d signify they're a "daemon," which is a process that runs in the background and doesn't accept user input. Then the kernel runs an "initialization" process, which is launchd on your Mac. The kernel is the core glue between the hardware and the operating system. When your computer boots, it loads the "kernel" program into memory and hands over control to it. Look at the top of the process tree, and you'll see that every process on your Mac is a child of two parent processes:Īll operating systems have a " kernel", the core computer program of the operating system that controls everything and facilitates access to hardware. In the htop process viewer interface, press t to switch to tree view. Once the install completes, run it by typing htop and hitting enter.

On your Mac, open a terminal and run brew install htop. Let's install the process viewing application htop to get an understanding of how containers work. Just replace Homebrew with your package manager. These instructions are tailed for MacOS users, but work for Linux users as well. Why, then, do Docker "image" files start with lines like FROM ubuntu? Are containers running full Ubuntu operating systems? If not, why do we specify an entire operating system? For that matter, what does it even mean to "run an operating system? In Docker, we run processes in isolated environments, such as Rails applications or Node.js applications. All posts tech nutrition growth Here's Why Docker Images Start With "FROM ubuntu"