By John Carmack 
Docker has become a popular tool for developers who want to run applications in isolated environments. It simplifies software installation by packaging everything needed to run an application, including dependencies, into one container.
To install software in a Docker container, use the Dockerfile. Add commands like RUN to install packages. Build the image with docker build and run it with docker run.
In this article, we will discuss “How To Install Software In A Docker Container”.
What You Need To Get Started?
Before knowing Docker, you need to set up the basic requirements.
1. Prerequisites:
- A working machine with an operating system (Windows, MacOS, or Linux).
- Basic knowledge of the terminal or command line interface (CLI).
2. Installing Docker On Your System:
You can download Docker from the official Docker website for your platform. Once installed, verify the installation by typing the following command in your terminal:
- docker –version
If Docker is correctly installed, it will display the version number.
Basic Docker Concepts:
1. Docker Images Vs. Containers:
Docker images are like templates that hold everything your software needs. Containers are instances of these images, running in isolation from the rest of your system. Think of images as blueprints, while containers are the structures built from them.
2. Docker Hub Overview:
Docker Hub is a public registry where you can find and store images. It’s a good place to search for ready-made images for various software applications.
Setting Up Docker Website
1. Checking Docker Installation:
After Docker is installed, ensure it’s working by running:
- docker run hello-world
This will pull a simple image and run it, confirming Docker is ready for use.
2. Running The First Docker Container:
Once you see the Hello from Docker message, you know your environment is set up. You are now ready to install the software in a Docker container.
Pulling A Docker Image
To install software, you first need a base image. This could be a lightweight Linux distribution like Ubuntu.
1. Using Docker Pull Command:
For example, to pull an Ubuntu image, run the following command:
- docker pull ubuntu
2. Finding Images On Docker Hub:
Visit Docker Hub to explore and find images of different software you might need.
Creating A Docker Container:
1. Running A Container From An Image
Once you have your image, create a container with:
- docker run -it ubuntu
This command launches a new container with interactive mode enabled, dropping you into a terminal session within the container.
2. Using Docker Run
The -it flags make sure you get an interactive terminal so you can execute commands inside the container.
Installing Software Inside A Docker Container:
Now, with your container running, you can install software just like you would on any Linux machine.
1. Accessing The Container’s Shell:
You should already be in the shell of the container after running the previous command. If not, you can access it by using:
- docker exec -it <container_id> bash
2. Installing Software Using Package Managers
Let’s install a package, like curl. Inside the container, run:
- apt update
- apt install curl -y
This installs curl inside the container.
Persisting Installed Software:
When you stop a container, all changes, including installed software, are lost. To save these changes, you need to create a new Docker image.
1. Using Dockerfile:
A Dockerfile allows you to define the setup of a container, including any software you want pre-installed. Create a Dockerfile that looks like this:
- FROM ubuntu
- RUN apt update && apt install curl -y
2. Committing Changes To A New Image:
Alternatively, after installing the software, you can commit the changes:
- docker commit <container_id> my_new_image
Now, every time you run my_new_image, curl will already be installed.
Running Software In A Docker Container:
1. Starting The Container With Installed Software:
You can start the container and use the installed software immediately:
- docker run -it my_new_image
2. Testing The Installed Software:
Run curl –version to check if the software was installed successfully.
Managing Docker Containers:
1. Stopping And Removing Containers:
When you’re done with a container, you can stop it with:
- docker stop <container_id>
To remove it entirely:
- docker rm <container_id>
2. Listing Active Containers:
To see which containers are running, use:
- docker ps
Saving And Sharing Your Docker Image:
1. Pushing An Image To Docker Hub:
You can share your image with others by pushing it to Docker Hub:
- docker tag my_new_image username/my_new_image
- docker push username/my_new_image
2. Sharing The Image With Others:
Now anyone can pull your image with:
- docker pull username/my_new_image
Use Cases For Software In Docker Containers:
1. Development Environments:
Docker is perfect for setting up isolated development environments where you can test your software.
2. Software Testing And Deployment:
It’s widely used for testing and deploying applications across different environments without compatibility issues.
How Do I Connect To A Docker Container?
To connect to a Docker container, use the command docker exec -it <container_name> /bin/bash. This opens a terminal inside the running container, letting you interact with it directly.
How Does A Docker Container Start?
A Docker container starts using the command docker run <image_name>. This creates and runs a container from the image. If it’s already created, use docker start <container_name> to restart the container.
How Do You Remove A Docker Container?
To remove a Docker container, use the command docker rm <container_name>. If the container is still running, stop it first using docker stop <container_name>, then remove it with docker rm.
How Do You Use Docker Containers?
Docker containers let you package applications and their dependencies into isolated units. You can run these containers on any system with Docker installed. This makes it easy to develop, ship, and manage apps consistently.
What Are Multi-Container Docker Applications?
Multi-container Docker applications use multiple containers to run different parts of an app. Each container handles a specific task, like databases or web services, making the app easier to manage and scale.
How Do You Install An Application In A Docker Container?
To install an application in a Docker container, create a Dockerfile with installation steps, then build the image. Run the container from this image, and the app will be ready to use inside the container.
Can We Install Software In A Docker Container?
Yes, you can install software in a Docker container. Use a Dockerfile to add installation steps, then build an image. The container will run with the installed software inside.
How To Deploy Software On Docker?
To deploy software on Docker, create a Dockerfile with setup steps, build an image, and run a container from it. You can then manage, scale, and update your software easily using Docker commands.
How To Install Command In Docker Container?
To install a command in a Docker container, add the installation command (like apt-get install) in a Docker file. Build the image, and the command will be available when running the container.
How To Install Code In Docker Container?
To install code in a Docker container, add your code files to the Dockerfile using the COPY command. Then, build the image, and your code will be included when running the container.
Is It Possible To Install Applications In the Docker Container Permanently?
Yes, it is possible to install applications in a Docker container permanently. Use a Dockerfile to install the application, then build an image. The installed application will be available whenever you run that image.
FAQs:
1. What Is A Docker Image?
A Docker image is a template containing the software and settings needed to create containers.
2. How Do I Install Docker?
Visit the official Docker website, download the appropriate installer for your system, and follow the instructions.
3. What Happens To Installed Software When A Container Stops?
By default, changes are lost when a container stops. You need to save them by creating a new image.
4. Can I Run Multiple Containers At The Same Time?
Yes, Docker allows you to run multiple containers simultaneously.
5. How Do I Share A Docker Image With Others?
Push the image to Docker Hub; others can pull it using your username.
Conclusion:
In this guide, you learned how to install software in a Docker container. By using Dockerfiles and Docker commands, you can easily create, run, and manage containers. This method makes it simpler to install, update, and share software in isolated environments.