A container needing systemd in it doesn't make much sense. If you need that, you might need to rethink the architecture. The purpose of a container is the run as a single service, if you have more than 1 service running in your container then you aren't using it properly. You can't use or think of containers as a normal OS or a virtual machine. Note - If you use the KDE and i3 flavors for Ubuntu need to be run in privileged mode to function properly Add 'privileged: true' in your docker-compose.yml file. For PUID and PGID, use the below. Oct 05, 2020 For the purposes of this post, I am installing Docker on an Ubuntu 18.04 Server. To install Docker inside an Ubuntu 18.04 Server, run the following commands: sudo apt-get update sudo apt install docker.io -y To verify that Docker is installed successfully and check the version, use the following command: docker –version. For example, if you want to install firefox inside an ubuntu container, you can specify them in the dockerfile in the following way −. FROM ubuntu RUN apt−get −y update RUN apt−get install firefox. To conclude, it is quite evident that a docker container is no different than any linux terminal. Sep 08, 2020 Step 3: Installing Docker. Now let’s install Docker on Ubuntu 20.04. Run the following command in the terminal window: sudo apt install docker.io. Type y and hit Enter to confirm the installation. Once the install is completed, the output notifies you Docker has been installed. Step 4: Checking Docker Installation.
After you have installed docker on your linux machine, the next step is to create an image and run a container. You need to create a base image of an OS distribution and after that you can add and modify the base image by installing packages and dependencies and committing the changes to it.
In this article, we will show you how to create an ubuntu base image and on top of that create intermediate image layers by adding packages in it and keep committing the changes. We will update the ubuntu base image, install 3 packages - vim editor, firefox and python 3.
Note that we can do this using two ways - either we mention all the commands inside a dockerfile and build the image all at once or we can do it step by step and keep committing the changes through CLI. We will discuss both the methods here.
Method 1. Step by Step using CLI.
Open a terminal and run the following command. Note that if you are not the root user, you need to add sudo before all the commands.
This will check if an ubuntu image exists locally or not. If it does not exist, it will display “Unable to find image 'ubuntu:latest' locally” message and start pulling it from docker hub. After pulling the image, it will run the apt update command.
We will now install a vim editor inside the container. For that, we will run the bash of the ubuntu image.
This will open an interactive ubuntu bash. Inside the bash, type the following commands one by one to install the packages.
The first command runs an update. It then installs vim editor, firefox and some dependencies for python 3. Then it adds the official python 3 repository and installs python 3.7 and then exits the bash.
You can check the version of python using the following command.
After exiting the bash, you need to commit the changes. Find out the container ID using the following command.
Copy the container ID and paste in the following command.
You can check that the new ubuntu image with the specified name and installed packages has been created using the following command.
Create a file name dockerfile and place the following commands in it.
Build the image using the following command.
This command builds the docker image using the dockerfile.
Run the docker image using the following command.
To conclude, the better method to create an image and install packages is by creating a dockerfile with the appropriate commands because it will help you to keep track of the changes that you make and the packages that you install and gives a better clarity of the whole project.
In this tutorial, we’ll learn how to use the vi command inside a Docker container. A basic understanding of Linux and Docker is required to fully understand this tutorial. We’ll look into four types of Linux distributions, namely, Ubuntu, Debian, CentOS, and Fedora.
Docker is a containerization platform that allows packaging our application and its dependencies into a single unit.
As a best practice, we should keep the Docker image size small. Therefore, we install only those packages inside the Docker container which are necessary to run our application.
The official Docker image of Ubuntu and Debian does not contain the vim package. Let’s verify this quickly:
First, we have launched an Ubuntu Docker container with its latest Docker image. Furthermore, apt list –installed grep vim will verify whether the vim package is present inside the container. Since the output is empty (ignore the warning), we can conclude that the vim package is not present in the container.
Now, let’s install the vim package manually inside the container:
Here, first, we’re updating the packages using the command apt-get update, and then we install the vim package using the command apt-get install -y vim:
Since we have installed the vim package above, the output of the command apt list –installed grep vim is not empty this time.
All these commands will work for the Debian Docker container as well.
The official Docker image of CentOS and Fedora includes the minimal installation of the vim package which has the capability to perform all the basic file edit operations.
Now let’s launch a centos Docker container using its latest Docker image. Again, we’ll verify if the vim package is available inside the container using the command rpm -qa grep vim.
We can install the complete vim package if required:
The yum update command will update the packages to their latest version. Finally, we’ll install the vim package using yum install -y vim. Both the commands will execute inside the Docker container.
Again, let’s verify all the vim packages installed inside the container:
All the commands discussed in this section will work on Fedora Docker containers as well.
Now that we have installed the vim package inside the Docker container, we can use the vi command to create and edit files:
Here, we’re starting an interactive Bash shell inside the Docker container and then creating the baeldung.txt file inside the / directory. If the baeldung.txt file is already present, it will open the file in the vi editor.
In this example, we should note that control will remain inside the Docker container. Any operation performed after this will execute inside the Docker container.
Let’s look at another way to perform the same operation using a single command:
This time, the control will remain on the host machine. Any operation performed after this will execute on the host machine.
To get an in-depth understanding of the vi editor and its different operations, it is highly recommended to read our guide.
Ideally, application development includes three major stages, namely, development, testing, and deployment. We should test the source code thoroughly before its deployment. Finally, we use Docker containers to deploy our source code.
At the deployment stage, Docker is used to package the application source code and all of its dependencies into a single entity. We should not update the source code once the application is deployed. All the changes should be done in the development stage only.
Hence, packages like vim, which is used to edit files, should be avoided inside the Docker image.
Even if, for any reason, we want to edit any file inside the Docker container, we should use Docker volumes.
Using Docker volumes, we can mount the source code directory onto a specific directory on the host machine. This way, any changes done inside the file present on the host machine will reflect the changes inside the Docker container.
The vim package requires disk space of approx 50 MB for installation. As an alternative, we can also use packages like nano or vim-tiny (available in Ubuntu only) for file editing. These packages require disk space of a few KB’s only. Therefore, our Docker image size will be small.
In this article, we went through the installation process of the vim package for different Linux distributions. Moreover, we have also examined the reason to avoid the installation of the vim package inside Docker containers.
Finally, we’ve discussed a couple of alternatives to the vim package which are small in size.