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Containerisation & Docker: Flexibility, efficiency and security for modern web projects

Stable infrastructure. Modular freedom.

In recent years, the way websites and applications are operated has changed fundamentally. Hosting used to be traditional: a dedicated server equipped with specific hardware, a fixed operating system and a PHP version formed the backbone of one or more websites. Anyone who wanted to run multiple projects with different system requirements was forced to provide additional servers – with high configuration, maintenance and cost expenses.

Containerisation has broken down these rigid structures and ushered in a new era of infrastructure – modular, portable, efficient and secure.

What is containerisation?

Imagine that every component of an application – be it the web server, the PHP version, the database or a cache – is located in its own isolated container. This container comes with all the necessary libraries, configurations and dependencies to run independently of the host system. This creates a kind of mini-server within the server that does exactly what it is supposed to do – no more and no less.

The containers run side by side on a shared server that provides the necessary computing power. Docker has established itself as the platform for deploying and managing these containers. Today, Docker is one of the most popular tools for containerisation – both locally in development and in production.

Why containerisation? An overview of the key advantages

1. Modular and flexible

A major advantage: services can be operated separately from one another. Want to run one application with PHP 7.4 and another with PHP 8.4? No problem. Both versions are located in their own container – on the same server, without interfering with each other.

In general, individual software componenten such as PHP, Varnish or Redis are no longer tied to the operating system or its version. Instead, they run in their respective containers and bring all the necessary libraries and dependencies with them. This allows for maximum flexibility in the selection of software versions and configurations, regardless of the underlying system.

2. Greater security through isolation

Containers are encapsulated from one another. If one container is compromised, the others usually remain unaffected. Access rights can also be restricted to the bare minimum – for example, so that the PHP container cannot access the database directly, but only via defined interfaces.

This is a clear advantage over traditional hosting, where, in extreme cases, an attack on one service could also affect other projects on the same server. Although protective mechanisms also exist there, container isolation offers an additional level of security.

3. Efficient use of resources

Containers can run smoothly on a single host system, but can also be distributed and bundled across multiple servers. This makes the utilisation of existing hardware much more efficient overall – regardless of whether it is a single server or a cluster.

What's more, resource allocation can be controlled in a targeted manner. If you want to go one step further, you can use a tool such as Kubernetes. This orchestration tool can automatically scale containers according to load and distribute resources intelligently – ideal for projects with traffic peaks or seasonal campaigns.

4. Development and deployment: a game changer

The strength of containerisation is evident not only in operation, but also in development. Setting up a production-ready development environment locally used to be time-consuming and error-prone. Today, all you need to do is export a configuration file – and the entire infrastructure, including the database, can be mapped locally. In just a few minutes, developers can work with exactly the same environment as on the live system.

Even more exciting: we use dynamic review stages. For each merge request in GitLab, a separate test environment is automatically set up – isolated, temporary and fully functional. This allows changes to be tested risk-free before they are transferred to the production system.

From live to local and back again: theoretically and practically possible

One interesting use case is the ability to ‘boot up’ live containers and test them in a near-live environment. The container contains all the necessary configurations and data – including potential errors. This allows bugs to be analysed and resolved directly in their context. The corrected version is then redeployed.

In contrast to classic setups, where development, test and production systems often differ in detail, the underlying container image ensures that exactly the same system environment is used everywhere – regardless of the machine. This makes debugging much easier and minimises environmental errors.

Even though this is still rather theoretical in our current setup, we are striving for this approach because it saves time and increases quality.

Scaling with Kubernetes: When things get bigger

Not every website needs Kubernetes – but for large platforms with lots of parallel access, this orchestration tool is a real game changer. Kubernetes can distribute containers across multiple servers, automatically start up new instances or shut down those that are no longer needed. The result: stable loading times, optimised resource utilisation and high reliability – even in the event of unexpected traffic spikes.

The future of hosting is modular and container-based

Containerisation makes web projekts significantly more efficient, secure and flexible. Tools such as Docker and Kubernetes not only offer advantages in infrastructure management, but also revolutionise development and deployment.

Whether it's a single project or a large platform with multiple services, once you've used containerisation, you'll never want to go back to the traditional hosting world. Because in a world that is getting faster and faster, we need infrastructure that can keep up.

In another article, we will delve deeper into practical applications and demonstrate how we implement containerisation in our projects.

Among other things, we will cover:

• Our containerisation setup in everyday agency work
• Secure operation through monitoring, backups, and error reporting
• Automated deployment with Git-based pipelines and dynamic review stages
• Scalability and efficiency – both technically and economically
• Sustainability through resource-saving infrastructure
• IT security and high availability through isolated processes

We hope you will read the next article – it will be worth your while.

→ Check your containerisation potential now