Docker Architecture

Containerization

Containerization is OS-based virtualization that creates multiple virtual units in the userspace, known as Containers. Containers share the same host kernel but are isolated from each other through private namespaces and resource control mechanisms at the OS level. Container-based Virtualization provides a different level of abstraction in terms of virtualization and isolation when compared with hypervisors. Hypervisors use a lot of hardware which results in overhead in terms of virtualizing hardware and virtual device drivers. A full operating system (e.g -Linux, Windows) runs on top of this virtualized hardware in each virtual machine instance. But in contrast, containers implement isolation of processes at the operating system level, thus avoiding such overhead. These containers run on top of the same shared operating system kernel of the underlying host machine and one or more processes can be run within each container. In containers you don’t have to pre-allocate any RAM, it is allocated dynamically during the creation of containers while in VMs you need to first pre-allocate the memory and then create the virtual machine. Containerization has better resource utilization compared to VMs and a short boot-up process. It is the next evolution in virtualization....

Docker Architecture

Docker architecture consists of Docker client, Docker Daemon running on Docker Host, and Docker Hub repository. Docker has client-server architecture in which the client communicates with the Docker Daemon running on the Docker Host using a combination of REST APIs, Socket IO, and TCP. If we have to build the Docker image, then we use the client to execute the build command to Docker Daemon then Docker Daemon builds an image based on given inputs and saves it into the Docker registry. If you don’t want to create an image then just execute the pull command from the client and then Docker Daemon will pull the image from the Docker Hub finally if we want to run the image then execute the run command from the client which will create the container....

Components of Docker

The main components of Docker include – Docker clients and servers, Docker images, Dockerfile, Docker Registries, and Docker containers. These components are explained in detail in the below section :...

Docker Compose

Docker Compose is a tool with which we can create a multi-container application. It makes it easier to configure and run applications made up of multiple containers. For example, suppose you had an application that required WordPress and MySQL, you could create one file which would start both the containers as a service without the need to start each one separately. We define a multi-container application in a YAML file. With the docker-compose-up command, we can start the application in the foreground. Docker-compose will look for the docker-compose. YAML file in the current folder to start the application. By adding the -d option to the docker-compose-up command, we can start the application in the background. Creating a docker-compose. YAML file for WordPress application :...

Docker Networks

When we create and run a container, Docker by itself assigns an IP address to it, by default. Most of the time, it is required to create and deploy Docker networks as per our needs. So, Docker let us design the network as per our requirements. There are three types of Docker networks- default networks, user-defined networks, and overlay networks....

Advantages of Docker –

Docker has become popular nowadays because of the benefits provided by Docker containers. The main advantages of Docker are:...