Docker: Containerization and PaaS have taken the software development world by storm. Containerization has grown to be established today as a standard in the modern-day software development environment. Within the context of Platform as a service (PaaS), containers have become critically useful software delivery tools. Containerization enables software interoperability while also enhancing the security of software. PaaS, on the other hand, provides developers with the platform for developing highly available and fully-functional software along with the services associated with them.
From YouTube to Gmail, Google and many other companies like Huawei and Red Hat have adopted the concept of containerization. Containerization enables a faster, highly scalable, and more efficient software development process. Owing to this, containerization technologies like Docker have gained prominence over the years. Subsequently, Docker training and other forms of containerization training matter to developers more than ever.
Containerization explained
Containers are lightweight standalone packages of applications that are shipped together with their code and other dependencies required for the applications to be deployed to run in various environments. These dependencies include configuration files, libraries, tools, and other executables. Containers separate applications from their environments, allowing them to operate uniformly in all the environments they will be deployed in. This way, containers become a form of operating system virtualization technology. This is to mean that containers, unlike servers or virtual machines, do not contain operating system images, which explains why they are lightweight and portable.
Containerization comes with several benefits including
- Operational efficiency where the roles of application developers and IT operations are well defined and streamlined. While developers focus on building and packaging applications with their dependencies in containers, IT operations focus on deployment infrastructure.
- Increases productivity during application development as applications is isolated from the environment in which they run.
- Enables consistency as the containers run in different environments for instance development and staging environments. This eases development and deployment whether on Windows, Linux, VMs, as well as on physical servers or in the cloud environment.
- For larger deployments, containerization enables the clustering of multiple containers to be deployed as one. This is usually effectively managed by a container orchestration technology like Kubernetes.
What is Docker?
Docker container technology was invented in 2013 and leverages Linux Kernel features like namespace and control groups to isolate application processes to run independently of the operating system they are built on. It is an open-source tool that developers use Docker to build, deploy, and ship containerized applications easily using simple commands and automated processes.
Docker eliminates the boring repetitive tasks like configuration that are common during software development through automated builds. Docker engine comprises CLIs, APIs, and UIs along with enhanced security for faster and more secure software delivery. Thus, Docker containers running on the Docker engine are standard, lightweight, and secure.
How does Docker work?
One benefit that Docker offers is the platform to run standardized code inside containers. It virtualizes the OS of a server so that the code runs in an isolated environment from the OS. ****
To begin with, install Docker on your server (cloud or desktop). From here you can build your Docker image that is structured in layers.
Set up automated builds using simple commands to build images from the source code from an external repository and ship it to your Docker repository. The image from the external repository will be your base image that after you have loaded with your desired software, you will commit to your repository and then give it a tag, hash, and branch to make it easy to retrieve.
Using Docker daemons, package a writable container layer over your Docker image. The container will then be assigned a container ID on completing this process. The Docker container created can then be run in different environments.
If you want to run Docker images at scale, multiple containers can be run in clusters and managed by an orchestration engine.
What are the advantages of using Docker?
Containerization has been adopted widely in software development and Docker, a containerization engine, has become ubiquitous to containers. Despite there being several other container technologies, Docker comes with valuable advantages.
- Docker containers are portable. Unlike LXC containers, Docker containers are designed to run across any environment, desktop, cloud, or others without first modifying it based on the build once, run anywhere concept. Images are stored in the Docker Hub or Docker Trusted Registry (DTS). Images can be retrieved from these registries and run on any platform on which the registry can be accessed. For example, applications can seamlessly be moved from production, staging, to deployment environment using Docker.
- Faster software build and deployments. On average, Docker developers ship code seven times more frequently compared to their counterparts who do not use Docker. This is because containers are lightweight and require minimum runtime.
- Docker enables version control and component reuse. Docker in itself is not a version control tool. Yet it is possible to track subsequent versions of a Docker image and roll back to previous versions in case of bugs and inconsistencies thanks to its layered structure. Also, existing Docker images can be used as base images when building new containers.
- Docker enables standardization of application operations. Deploying and running applications inside containers makes it easy to pick up bugs and roll back to fix them.
- Automated build. Docker is a service model for SaaS and PaaS platforms and has been used widely to automate systems and streamline operations. Docker can be automated to build images and run them in containers automatically using an automated script.
- Cost-effective scalability. As we have already seen, Docker can be used to build, deploy, and run images at scale while still offering the advantage of lightweight images and faster deployments to reduce overheads.
Docker is core to application and platform development
To begin with, Docker containers make it fast and easy to build, deploy, and run standardized code and distributed microservice architectures, and establish streamlined systems and applications. In addition, it has also enhanced continuous integration and continuous delivery (CI/CD) pipelines in software development methodologies like DevOps. Further, Docker has proved useful for big data processing even with Docker container-based systems in the cloud becoming the norm in the big data analytics field.
Finally, in an era of digital transformation where many enterprises are shifting their operations and applications into the cloud, Docker is more than handy. Currently, over 11 million developers have adopted Docker to reflect the usefulness of Docker in software development.
