Docker is a great tool for building micro-services, allowing you to create cloud-based applications and systems.
It is a container management service which is based on the concept of Develop, Ship and Run anywhere. To develop apps and ship them into containers which can be deployed on any platform.
With the initial release of Docker technology in March 2013, there was an embarkment of new technical term - Containerization. It has started revolutionizing the old concept of virtualization, where we need to build a complete Guest OS on top of a host OS to run an application.
Virtual machines are resource-intensive as they consumes a lot of resources (compute, memory,etc) in runtime whereas containers are lightweight and boots up in seconds.
The basic architecture of Docker is a Client-Server architecture and consists of 3 major parts:
1. Docker Host - Docker Host runs the Docker Daemon. Docker Daemon listens for Docker requests. Docker requests could be ‘docker run’, ‘docker build’, anything.
It manages docker objects such as images, containers, networks, and volumes.
2. Docker Client - Docker Client is used to trigger Docker commands. It sends the Docker commands through a CLI to the Docker Daemon. It can communicate with more than one daemon.
3. Registry - The Registry is a stateless, highly scalable server-side application that stores and lets you distribute Docker images. You can create your own image and upload it to Docker Hub or any other specified registry.
When we run the command docker pull or docker run, the required images are pulled from your configured registry.
A container is a special type of process that is isolated from other processes. Containers are assigned resources that no other process can access, and they cannot access any resources that are not explicitly assigned to them.
Docker containers are evolved from LXC (Linux Containers)
LXC is the well-known and heavily tested low-level Linux container runtime. It is in active development since 2008 and has implemented various well-known containerization features inside the Linux kernel.
The goal of LXC is to create an environment as close as possible to a standard Linux installation but without the need for a separate kernel. To read more about LXC here.
Docker Daemon/Engine is evolved from LXD (LXD daemon)
LXD is a next generation system container manager. It offers a completely fresh and intuitive user experience with a single command line tool to manage your containers. Containers can be managed over the network in a transparent way through a REST API.
See you in the upcoming tutorials for taking a deeper dive into Docker.
It is a container management service which is based on the concept of Develop, Ship and Run anywhere. To develop apps and ship them into containers which can be deployed on any platform.
With the initial release of Docker technology in March 2013, there was an embarkment of new technical term - Containerization. It has started revolutionizing the old concept of virtualization, where we need to build a complete Guest OS on top of a host OS to run an application.
Virtual machines are resource-intensive as they consumes a lot of resources (compute, memory,etc) in runtime whereas containers are lightweight and boots up in seconds.
Virtualization vs Containerization
Architecture of Docker
The basic architecture of Docker is a Client-Server architecture and consists of 3 major parts:
1. Docker Host - Docker Host runs the Docker Daemon. Docker Daemon listens for Docker requests. Docker requests could be ‘docker run’, ‘docker build’, anything.
It manages docker objects such as images, containers, networks, and volumes.
2. Docker Client - Docker Client is used to trigger Docker commands. It sends the Docker commands through a CLI to the Docker Daemon. It can communicate with more than one daemon.
3. Registry - The Registry is a stateless, highly scalable server-side application that stores and lets you distribute Docker images. You can create your own image and upload it to Docker Hub or any other specified registry.
When we run the command docker pull or docker run, the required images are pulled from your configured registry.
What are containers?
A container is a special type of process that is isolated from other processes. Containers are assigned resources that no other process can access, and they cannot access any resources that are not explicitly assigned to them.
The technology behind the containers!!
Docker containers are evolved from LXC (Linux Containers)
LXC is the well-known and heavily tested low-level Linux container runtime. It is in active development since 2008 and has implemented various well-known containerization features inside the Linux kernel.
The goal of LXC is to create an environment as close as possible to a standard Linux installation but without the need for a separate kernel. To read more about LXC here.
Docker Daemon/Engine is evolved from LXD (LXD daemon)
LXD is a next generation system container manager. It offers a completely fresh and intuitive user experience with a single command line tool to manage your containers. Containers can be managed over the network in a transparent way through a REST API.
Features of Containers:
- Complete isolation - Two containerized processes can run side-by-side on the same computer, but they can’t interfere with each other. They can’t access each other’s data unless explicitly configured to do so.
- Shared physical infrastructure - We don't need separate hardware for running different applications. All can share the same hardware. Shared hardware means lower costs.
- More Secure - Since there is sharing of hardware only but the processes and data being isolated so it becomes very secure.
- Faster scaling of applications - The creation and destroying time for containers is negligible. Even there is no need to purchase the physical infrastructure for scaling up of an application like it used to happen many years ago.
The future of Docker
As the technology shifted from mainframes to PC, Baremetal to Virtualization, Datacenters to Cloud. Now is the time for moving from host to containers (going serverless).
As per the trend analysis, By 2020, more than 50% of the global organizations will be running containers in production.
After going through many articles, I can infer that trend in technology has inclined more towards Kubernetes after DockerCon 2017 as the Swarm (Docker's inhouse container orchestration tool) started seeing a tough competition.
Though the simplicity of the Docker Swarm as the container orchestrator that has taken Docker to this level.
We haven't seen any recent development in Docker Swarm repository from quite a long time. (https://github.com/docker/swarm/wiki)
Even Docker itself has adopted Kubernetes as a container orchestrator.
Is this an indication that the Docker Swarm will be soon out of the picture as more and more industries start adopting Kubernetes in their architecture.
Needless to say that the docker has survived till now and will keep running as an organization, regardless of the speculations that some big organizations will acquire it. There are a lot of new upcoming features and development still going on.
Incorporating cgroups v2 will give Docker better resource isolation and management capabilities.
Adopting P2P model for image delivery and distribute images using something like BitTorrent sync.
Referenced Articles:
See you in the upcoming tutorials for taking a deeper dive into Docker.
Thanks for sharing useful information.. we have learned so much information from your blog..... keep sharing
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