How to launch a container in Docker

A Docker container is a lightweight and isolated environment that contains everything you need to run an application, including code, dependencies, libraries, and settings. It uses containerization to package and deliver applications using standardized processes.

What are containers in Docker?

They work on the basis of Docker images that contain all the components of the application and its dependencies. Images are created based on Dockerfile files that contain instructions for building the image. When an image is created, it can be launched as a container.

Docker containers provide isolation of applications from each other and from the host system. They use the host operating system kernel, but have their own environment, including the file system, environment variables, network interfaces, and processes. This allows them to work independently of other containers and ensures the repeatability and reliability of running applications in different environments.

They also have scalability and portability. They can be easily transferred from one system to another without changing the code or settings. Docker containers also integrate with orchestrators such as Docker Swarm or Kubernetes to manage and deploy containerized applications in a clustered environment.

How to launch containers?

To run a container in Docker, you will need to follow these steps:

 Install Docker on your machine if you haven't already. You can find instructions for installing Docker on the official Docker website:

1. Prepare a Dockerfile that defines the settings and instructions for creating a container. A dockerfile is a text file, usually without an extension, that contains commands to build a container image. An example of a simple Dockerfile might look like this.
2. Using the base image.
3. FROM ubuntu:latest
4. Installing the necessary packages.
5. RUN apt-get update && apt-get install -y <packages>.
6. Copying files to a container.

Running the command when starting the container

CMD <command>

Open a command prompt or terminal and navigate to the directory where your Dockerfile is located.

Assemble the container image by running the command `docker build -t <image_name>.`.

Here `<image_name>` is the name you choose for your image, and the dot `.` points Docker to the current directory where Dockerfile is located.

After successfully assembling the image, run the container using the `docker run <image_name>` command. This will create and launch a container based on your image.

It is important to note that when starting a container, you can use various flags and parameters to configure its behavior, such as port forwarding or directory mounting. For more information about the available parameters and flags, run the `docker run --help` command.