How to Manage DevOps and Deployment Pipelines for Containerized Applications
A discussion on DevOps cannot be complete without an analysis of containerization and the role it plays in deploying applications. It has also become a major trend in software development and is currently being deployed as an alternative or a supporting process to virtualization. This is why it is important to understand the history of containerization technology and the advantages of using it. Also, to better appreciate these benefits, how DevOps and deployment pipelines can be managed through containerization must be understood.
In this article we take a detailed look at the process of containerization as well as the process of managing DevOps for containerized applications. The article will discuss:
- Containers and containerization including its applications.
- Container platform providers with an emphasis on Docker.
- Image management and container manipulation in DevOps.
- Running containers on AWS and the benefits.
An Introduction to Containers and Containerization
Containers or application containers are lightweight runtime environments that provide apps with the necessary files, variables, and libraries they need to run or function. Application containers are called lightweight because they share the operating system kernel of machines. Containers also help maximize the portability of applications because of the shared operating system which eliminates the need to integrate operating systems with every application. This means containers enable the virtualization of software applications.
Containerization is basically the use of containers in software development. It involves the packaging of software code and its varying dependencies which ensures the software can run uniformly and optimally on any infrastructure it is deployed on. This means you can write an application and run it anywhere you choose without having to tweak code to fit diverse infrastructures. From the definition, some advantages of containerization are immediately apparent. These advantages include:
- Enhanced security because each container is isolated and does not inherit external security issues.
- It allows for the speedy creation and deployment of applications because they share operating systems.
- Containers are easier to manage and troubleshoot.
An Overview of Docker and Its Benefits
For a simple overview of application containerization and how it works, here are the three major steps used in creating containers:
- A manifest describing the container
- Creating the container image
- Creating the actual container with the relevant libraries, runtimes, and dependencies.
Once this is done, the next step is getting the container to run when deployed in a machine or infrastructure. To do this, a runtime engine must be used. A runtime engine is a software that the container depends on to run when deployed. There are diverse types of container platform providers with runtime engines that can be used to run containers and the Docker Engine is the most commonly used option today.
Docker’s popularity is due to the role it played in standardizing the use of containerization. Docker is an open platform that can be used to build, ship, and run applications on different infrastructures. These infrastructures or environments include the cloud, data centers, laptop, personal computers, etc. Docker is divided into three main parts which include; the Docker software, the containers, and the Docker hub repository.
Docker simplifies the use of containerization in DevOps as it supports the creation of applications and moving apps alongside their settings and configurations across diverse platforms. It also supports scaling and enables the creation and launch of multiple containers as the need arises. This makes it easier to introduce changes or updates to irregular architecture with relatively less risk when compared to other methods. Using Docker containers also eliminates the risks attached to driver compatibility issues, version conflicts, and other server related issues when deploying applications.
Containers also solve the traditional issue of resource waste associated with traditional architecture. Containers can be built to deliver an on-demand capability and should be disposable. This means as a container executes its task it can be immediately destroyed unlike traditional architecture where apps stay permanently. The ability of a container to deploy and destroy on-demand eliminates the over-bloating associated with traditional infrastructures.
Container Images and Image Management
Container images are static files that include executable code that can run isolated processes in containers or other IT infrastructure. It’s worth noting that Docker images are a bit different than those from other VM environments. The major difference is that once a Docker image is built, it cannot be changed or edited. This feature also gives its own benefits during DevOps.
In DevOps, image management comes in different forms which include; searching for images, publishing images, shutting down and restarting virtual machines using the image. Shared images can also be used to start new virtual machines that run perfectly which is why public and private image registries exist. In Docker, image management is handled using Docker Hub and the Docker Registry. These options allow you to build and manage a private registry or access Docker’s public registry.
Public registries contain images published or shared by developers and it gives you a repository to also publish and access your personal images. Accessing or making use of container images in registries may come with security challenges and usability issues which may derail a project. This is why best practices must be adhered to when using images from registries. These best practices include:
- Scanning container images for vulnerabilities using scan tools before deploying.
- Ensuring new images are built every time the base image is updated.
In DevOps, a continuous integration and deployment pipeline should be provisioned to handle image scanning, verification, and deployments. The automated build process of new images when updates occur to the base image should also be integrated into the validation and deployment pipeline
Container Manipulation and Orchestration
Container manipulation provides an avenue for a developer to control the functions of an application. In basic manipulation, the container will integrate commands for starting, stopping, restarting, attaching, and detaching containers. Having an in-depth understanding of container manipulations creates an avenue for running tests by starting containers and disposing of the containers after the test has been completed.
To accomplish this, tools like Dockerode can be used to programmatically manipulate containers and their actions. For example, multiple containers running in a machine can be listed to know which is currently running and the containers in a host. Also, the Docker exec command can be used to import a database inside a container.
When manipulating hundreds or thousands of containers and services, container orchestration is needed to manage a scaled-up environment. It involves the use of orchestration tools such as Docker Swarm, Kubernetes (K8s), or OpenShift to control and automate the deployment, management, and networking of these containers. When using a container orchestration tool, the application is configured to know where to gather container images, store logs, establish network relationships between containers, and schedule deployments.
Choosing Operating Systems for Containerized Applications
As stated earlier, containers are built to run optimally on any operating system but in certain cases, an operating system may have the necessary features needed to bring out the best in particular applications. This is why developers must know the best OS options that have features that are critical to an application’s performance. With this in mind, the operating system options available to developers are:
- Full-Featured Operating Systems – These operating systems are the traditional OSs commonly used in DevOps. They are built with almost every feature an application may need to function optimally. Some examples of fully-featured OSs include Ubuntu and CentOS.
- Minimal Operating Systems – These operating systems are equipped with the minimal features needed to run applications. These operating system deliver a leaner less complex application which is required in certain situations. Examples of minimal operating systems include Alpine Linux and Busy Box.
- Container Operating Systems – These operating systems are generally designed to function as host operating systems. They are integrated with automation and container orchestration capabilities straight out of the box. Some popular container OSs available to developers include the Rancher OS and Container Linux.
The environment or IT infrastructure an application is being built for should determine choice. In situations where the server focuses on hosting containers, a container OS or a Minimal OS may be best. If containerized applications and non-containerized applications are considerations, then a dull-featured OS is the better option to use.
Running Containers on AWS
AWS provides a highly scalable platform that supports Docker containers and other container platforms. Using AWS, Docker containers can easily be run and containerized applications can be scaled with ease using Amazon’s Elastic Container Services. Container manipulation can also be executed using simple API calls to control containerized applications within the AWS environment. This means the need to provision and manage servers no longer stands and AWS security groups and networks can be taken advantage of. This gives you a powerful base for your containerized applications.
The use of containers in DevOps is an efficient way to optimize your applications for high-performance. To ensure this, here are a few best practices to consider when developing your Docker environment:
- Ensure you dictate or specify the percentage of processor time every container is granted.
- Limit the container memory allocation to ensure container memory commitments do not increase and slow down the environment.
- Manage Block IO bandwidth assigned to containers to ensure the environment runs optimally.
Finally, the true power of containerization rests in its ability to execute complex computing tasks while using minimal resources. Thus, leveraging on the capabilities of containerization will translate to a lower cost of owning your IT infrastructure. This is why 60% of enterprises currently take advantage of containerization and this number is only set to increase by 2021.
The technical nature of containerization means to properly leverage its capabilities and reap the benefits outlined here requires a complete understanding of the technology behind it. Stratus10 is positioned to help you reap these benefits and apply best practices when designing your containerization applications for your IT infrastructure.