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Container Security 101: How to Deploy Secure Containerised Applications

by Metsi Security | July 06, 2023

Container Security 101: How to Deploy Secure Containerised Applications

Containerisation is a popular technology that allows developers to package applications and their dependencies into isolated, lightweight, and portable units. However, containerisation also introduces new security challenges that require careful consideration and mitigation. In this blog post, we will discuss some of the key aspects of securing containerised applications throughout the deployment process, from building secure container images to monitoring and logging container activities.

Secure Container Images

One of the first steps to ensure the security of containerised applications is to establish a secure container image supply chain. This means using trusted base images from reputable sources and regularly updating them with the latest security patches. Additionally, it is important to implement vulnerability scanning tools that can analyse container images for known vulnerabilities and ensure that only secure images are used in the deployment process.

Another aspect of securing container images is to enforce security best practices for building them, such as minimising image size, reducing the attack surface, and applying appropriate access controls. For example, it is advisable to use multi-stage builds to remove unnecessary components and dependencies from the final image, use non-root users to run containers, and avoid storing sensitive data or secrets in the image.

Container Runtime Security

Securing the container runtime environment is another crucial step for ensuring the security of containerised applications. This involves leveraging container runtime security tools that monitor the behaviour of containers at runtime, detecting and preventing malicious activities. For instance, some of these tools can enforce policies that restrict the system calls, network connections, or file system operations that containers can perform.

Another way to enhance container runtime security is to utilise container security platforms that provide capabilities like container isolation, granular access controls, and runtime threat detection. These platforms can help isolate containers from each other and from the host system, limit the privileges and resources that containers can access, and identify any suspicious or anomalous behaviour in real-time.

Container Orchestration Security

Most containerised applications are deployed using a container orchestration platform, such as Kubernetes, that automates the management, scaling, and networking of containers. However, securing the container orchestration platform is also essential for ensuring the security of containerised applications. This involves following best practices for securing the control plane and worker nodes of the orchestration platform, such as encrypting data at rest and in transit, hardening the host systems, and using firewalls and network segmentation.

Another key aspect of container orchestration security is to enable RBAC (Role-Based Access Control) to enforce fine-grained access controls and restrict unauthorised access to the orchestration platform. RBAC allows defining roles and permissions for different users and groups based on their responsibilities and needs. For example, RBAC can be used to limit who can create, modify, or delete pods, services, or namespaces in Kubernetes.

Furthermore, it is essential to regularly patch and update the orchestration platform to address any known security vulnerabilities. This can be done by using automated tools that scan for vulnerabilities and apply patches as soon as they are available.

Runtime Monitoring and Logging

Monitoring and logging container activities is another important aspect of securing containerised applications. Monitoring and logging solutions can help collect metrics and logs from containers and provide dashboards and visualisations that show the performance and health of containers. Moreover, monitoring and logging solutions can help detect anomalies, suspicious activities, or security breaches in real-time by using log analysis tools that apply rules or machine learning algorithms.

Additionally, it is important to set up alerts and notifications to quickly respond to security events and take appropriate actions. For example, alerts can be triggered when a container exceeds a certain threshold of CPU or memory usage, when a container makes an unusual network connection, or when a container exhibits malicious behaviour.

Continuous Integration and Deployment (CI/CD) Security

The last step in securing containerised applications is to integrate container security scanning into the CI/CD pipeline. The CI/CD pipeline is the process of automating the delivery of code changes from development to production. By integrating container security scanning into the CI/CD pipeline, developers can ensure that their code is free of vulnerabilities before deploying it to production. For example, some of the steps that can be performed in the CI/CD pipeline are:

  • Scanning code repositories for secrets or credentials that may have been accidentally committed.
  • Scanning source code for common vulnerabilities or coding errors using static analysis tools.
  • Scanning container images for vulnerabilities or misconfigurations using dynamic analysis tools.
  • Scanning deployed containers for runtime threats or compliance violations using runtime analysis tools.

By implementing these steps in the CI/CD pipeline, developers can achieve a shift-left approach to security that identifies and fixes issues early in the development cycle rather than later in production.


Containerisation is a powerful technology that offers many benefits for developing and deploying applications. However, it also poses new security challenges that need to be addressed throughout the deployment process. By following some of the best practices and using the appropriate tools and platforms covered in this article, developers can deploy secure containerised applications that meet their business and security objectives.

If you are interested in learning more about how to deploy secure containerised applications, or if you need help with your container security strategy, grab a coffee with one of Metsi’s security experts to get started.