Basic Knowledge of DevOps Using Containerization and Docker (2)

This article follows the first content about devops docker and containerization, and it introduces the details about the relationship between containerization and docker.

The difference between containers and virtual machines (VMS)
Virtual machines can run multiple instances of multiple operating systems on the host without overlap. The host system allows Guest OS to operate as a single entity. Docker containers do not put too much burden on the system like virtual machines, because running the OS requires additional resources, which reduces the efficiency of the computer.

Docker containers do not burden the system and use only the minimum resources required to run the solution without emulating the entire operating system. Because Docker applications require fewer resources, it can allow a large number of applications to run on the same hardware, thereby reducing costs.

However, it reduces the isolation provided by the VM. It also increases homogeneity because if the application runs on Docker on one system, it will also run on Docker on other systems without any failure.

Both containers and VMs have virtualization mechanisms. But for containers, the operating system is virtualized. In the latter, hardware virtualization is performed.

VM performance is limited, while compact and dynamic containers with Docker have better performance.

VMs require more memory and therefore have more overhead, and they are more computationally intensive than Docker containers.

Docker terminology
Here are some commonly used Docker terms:

Dependency-Contains the libraries, frameworks and software needed to form the environment, and can simulate the medium for executing applications.
Container image-a software package that provides all the dependencies and information needed to create a container.
Docker Hub-A public image hosting registry where you can upload images and process them.
Dockerfile-Contains text instructions on how to build Docker images.
Warehouse-a network-based or Internet-based service for storing Docker images, there are private and public Docker warehouses.
Registry-a service that stores warehouses from multiple sources. It can be public or private.
Docker Compose-A tool that helps define and run multiple container Docker applications.
Docker Swarm-A cluster of machines created to run Docker.
Azure Container Registry – Registry provider for storing Docker images
Orchestrator-A tool that helps simplify cluster and Docker host management.
Docker Community Edition (CE) – a tool to provide development environments for Linux and Windows containers.
Docker Enterprise Edition (EE)-another set of tools for Linux and Windows development.
Docker containers, images and registry
Use Docker to create a service and then package it into a container image. Docker images are virtual representations of services and their dependencies.

The instance of the image is used to create a container to run on the Docker host. Then store the image in the registry. A registry is required to deploy to the production coordinator. Docker Hub is used to store it in its public registry at the framework level. Then deploy the image and its dependencies to the environment of your choice. It is important to note that some companies also provide private registration forms.

Business organizations can also create their own private registry to store Docker images. If the image is confidential and the organization wants a limited delay between the image and the environment in which the image is deployed, a private registry can be provided.

How does Docker perform containerization?
Docker image containers or applications can run locally on Windows and Linux. Just interact with the operating system directly through the Docker engine, you can use system resources to achieve.

To manage clusters and composition, Docker provides Docker Compose, which helps run multiple container applications without overlapping each other. Developers can also connect all Docker hosts to a single virtual host through Docker Swarm mode. Later, use Docker Swarm to extend the application to multiple hosts.

Thanks to Docker containers, developers can access the components of the container, such as applications and dependencies. The developer also owns the framework of the application. Multiple containers that depend on each other on a single platform are called "deployments." However, at the same time, professionals can pay more attention to selecting the appropriate environment for deployment, expansion, and monitoring. Docker helps limit the chance of error, which may occur during application transfer.

After the local deployment is complete, they will be further sent to code repositories like Git repositories. The Dockerfile in the code repository is used to build a continuous integration (CI) pipeline to extract the base container image and build a Docker image.

In the DevOps mechanism, developers are committed to transferring files to multiple environments, while management professionals are responsible for managing the environment to check for defects and send feedback to developers.

Future-oriented containerization strategy
It is always a good idea to predict the future and prepare for scalability based on project needs. Over time, the project becomes more and more complex, so it is necessary to implement large-scale automation and provide faster delivery.

Dense and complex containerized environments require proper handling. In this case, software developers can adopt PaaS solutions to focus more on coding. There are many options when choosing the most convenient platform to provide better and advanced services. Therefore, it is very troublesome to determine the correct platform according to the application of the organization.

For your convenience, we have listed some parameters to consider before choosing the best containerized platform:

1. Flexible and Natural
In order to obtain smooth performance, it is important to manually pick up a platform, which can be easily adjusted or changed according to the nature of the demand, and can be automatically performed.

2. Lock level
In fact, PaaS solution providers are usually proprietary, so they tend to lock you in an infrastructure.

3. Innovation space
Choose a platform that should have extensive built-in tools and third-party integration technologies to encourage developers to make way for further innovation.

4. Cloud support options
When choosing the right platform, it is crucial to find a platform that supports private, public, and hybrid cloud deployments in response to new changes.

5. Pricing model
Since it is natural to choose a containerized platform that supports long-term commitments, it is important to understand which pricing model is offered. There are many platforms that can provide different pricing models on different operating scales.

6. Time and energy
Another key aspect to remember is that containerization does not happen overnight. Professionals need to spend time reorganizing the architectural infrastructure. They should be encouraged to run microservices.

In order to change from the traditional structure, it is necessary to decompose the large application into smaller parts, and then distribute these parts to multiple connected containers. Therefore, it is recommended to hire experts who will make every effort to find a convenient solution to deal with virtual machines and containers on a single platform, because it takes time to make an organization completely dependent on containers.

7. Compatible with older applications
When it comes to modernization, old IT applications should not be ignored. With the help of containerization, IT professionals can take advantage of the benefits of these classic applications to properly utilize their investment in the old framework.

8. Multi-application management
Make full use of containerization by running multiple applications on the container platform. Invest in new applications at the lowest cost, and make changes to each platform by making them friendly to current and legacy applications.

9. Security
Because containerized environments have the ability to change faster than traditional environments, it has some major security risks. Agility can benefit developers by providing quick access. However, if the required security level cannot be ensured, it will fail.

One of the main problems encountered when dealing with containers is that dealing with container templates packaged by third parties or untrusted sources may pose a great risk. Therefore, it is best to verify publicly available templates before using them.

Organizations need to enhance and integrate their security processes to develop and deliver applications and services worry-free. With the modernization of platforms and applications, security should become a top priority for enterprises.

in conclusion
In order to keep pace with the fast-changing IT industry, professionals should continue to pursue better, so new tools available on the market should be used to enhance security.