DevOps needs three things: people with the right attitude, shared processes and the right tools. Docker software containers helps solve these challenges and offers a standardized platform for development and operation.
Container from the perspective of the developer
From a web agency perspective, each project places different demands on the target system, such as different versions of programming languages and frameworks. These combinations must be thoroughly tested during development through Continuous Integration (CI), which is time-consuming and prone to error with traditional systems.
Container virtualization, for example with Docker, helps. Docker uses so-called images, compilations of software to launch individual instances of an app, called containers. Unlike traditional virtual machines, these images do not include an operating system and are therefore lighter and faster. Ideal for continuous integration.
From the perspective of the software developer, it is easy to configure the pipelines with Docker, for example within GitLab CI. The image is specified and the runner takes care of everything else. The application is thus tested encapsulated and requires no additional software on the server.
Container from the perspective of the operator
Docker containers are a standardized and efficient way to package software with everything it needs to run. On the one hand, this helps to minimize external dependencies at runtime, so that the versions of PHP, Java etc. used in the correct version with all required modules, extensions and plugins are not yet to be managed separately on the server.
On the other hand, a change of the application code is exactly the same as a change of the application server: a new version of the container image is automatically built and deployed in the test environment, then the same checked image can be rolled out in the production environment.
The Advantages of Standardizing the Software Containers are Analogous to the Containers in Logistics
- Standardization makes containers more efficient: Just as a container ship transports 21’000 different containers with the same crew, a PaaS-provider can operate hundreds of thousands of containers on various customer infrastructures and cloud providers.
- Containers standardize the handling of contents: in logistics, the pick-up points in the corners are exactly the same whether the contents are liquid, solid or gaseous. In software, entrypoint, list port and storage volumes are defined exactly the same, no matter whether PHP, Java or .NET Core should be executed.
- Container technology is portable, so it works on all infrastructures and vendors just like any other means of transport.
The solution of software logistics is therefore called container orchestration and the most well-known implementation thereof is Kubernetes. It standardizes and automates software operations such as deployment / update, scaling, load-balancing, service discovery, storage volume management, monitoring, backup, distribution of containers to multiple servers and isolation of multiple applications, test environments, teams and / or customers.
So what does that mean for you – should you containerize your application?
There may be many different reasons why you may be reluctant to use Docker or container technology in general. You may be used to the classical way of building and testing applications using traditional VM technology or fear the migration effort, or you might not have the internal know-how or resources. Or you might have a legacy application which isn’t easily transferable or movable to the cloud.
So should you jump on this bandwagon – or to stay with the same terminology – ship?
A well-prepared DevOps team leveraging the potential of container technology can rapidly manage the deployment of applications without a substantial increase in either manpower or long-term costs. Moving your application to the cloud will be way easier using container technology like Docker, Kubernetes or OpenShift.
It can also make it significantly easier to scale the application, provide access to helpful auxiliary services and just in general make it more future-proof. So if you are coming from a legacy application, it probably will pay off in the future to invest resources now to make your application container ready.
Unifying the different environments using open-source Docker software container technology helps you leverage the world-wide ecosystem and experience. The more parts of the process that you can automate and integrate, the more efficiently you can build and launch your application.
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