Kubernetes vs Docker: What are containers?
Understanding the topic begins with understanding containers. Containers are units of code that include all the libraries and dependencies an application needs in a single package.
Often, containers are compared to virtual machines, but they are different in several key ways:
- Containers and virtual machines provide abstraction at different layers: Containers provide abstraction at the application layer, while virtual machines provide abstraction at the hardware layer. This means containers allow enterprises to package and run applications and services while virtual machines enable enterprises to run complete operating systems.
- Containers are more lightweight: Because they don’t include everything needed for a complete operating system, containers tend to take up less storage space and boot faster than virtual machines.
- They provide different levels of logical isolation: Containers offer less logical isolation than virtual machines. Virtual machines completely logically isolate operating systems and kernels, while all the containers on a system share the same kernel.
One of the fundamental problems containers solve is the “it works in my environment” challenge that traditionally plagued IT ops where an application works in development but not production. With containers, as long as you have an underlying container engine (like Docker Engine), you can run the exact same workload across any hardware, operating system, or cloud.
Understanding Docker
Docker is a platform that helps enterprises package and run containers.
While other platforms enable enterprises to work with containers, Docker has gained popularity thanks to its ease of use and scalability. Today, Docker is a staple of cloud-native apps that use microservices architecture and CI\CD pipelines at enterprises of all sizes.
With Docker, enterprises use plaintext Dockerfiles to help create containers. A Dockerfile contains instructions (commands) that help Docker automatically build a container image. A Docker container image is an immutable template that becomes a container once it is run. A Docker container is what actually runs workloads and adds a writable container layer on top of the immutable container image. Because the Docker container images are immutable, enterprises can reliably and repeatedly instantiate the exact same container across environments.
Understanding Kubernetes
While Docker is a tool for creating and running containers, Kubernetes is a tool for container orchestration.
With Kubernetes, enterprises can manage clusters of containers — including Docker containers — at scale. For example, Kubernetes enables resource configuration (e.g. RAM per container), auto-scaling, load balancing, and change rollouts (or rollbacks) for enterprise applications.
Because they serve two different purposes, Kubernetes vs Docker isn’t an either-or topic. In fact, in many cases, Docker and Kubernetes are used together across DevOps pipelines. However, in addition to the Docker platform, the company Docker, Inc. also offers Docker Swarm which is a container orchestration tool comparable to Kubernetes.
Docker Swarm vs Kubernetes
Unlike Kubernetes vs Docker, Docker Swarm vs Kubernetes is an apples-to-apples comparison. Both are open-source container orchestration platforms that enterprises can use to manage and scale container deployments.
While both are viable options for container orchestration, Kubernetes has emerged as the clear favorite among modern enterprises. In fact, the most recent RedHat State of Kubernetes report found that 88% of the DevOps, engineering, and security professionals that responded use Kubernetes.
Some of the reasons for Kubernetes dominance include its robust feature set, support for multiple container runtimes (containerd, CRI-O, Docker Engine, and Mirantis), and powerful abstractions using concepts like Pods and ReplicaSets.
However, Docker Swarm is generally considered more lightweight and less complex than Kubernetes, which can make it useful for enterprises looking for a simple container orchestration solution. While Docker Swarm “Classic” is no longer actively supported, current versions of Docker Engine include Docker Swarm mode. Swarm mode enables enterprises to use the Docker CLI for container orchestration tasks.
While Docker Swarm lacks the advanced features of Kubernetes — for example, Swarm has limited network configuration support and only supports the Docker runtime — it tightly integrates with other components of the Docker ecosystem such as Docker Compose and Docker Registry.
Docker Swarm is indeed a quality option for simple Docker container orchestration, but it isn’t the only option. In August 2020, K3s (Lightweight Kubernetes), was accepted as a Cloud Native Computing Foundation (CNCF) Sandbox project and already has over 19,000 stars on GitHub.
How to Ensure Container Security
Regardless of the container orchestration platform or container engine an enterprise uses, securing container workloads is a must. Because containers are fundamental components of enterprise infrastructure, they are also high-value targets for attackers.
From cryptomining exploits in container images to container escape vulnerabilities like the runc flaw in CVE-2019-5736, enterprises must ensure their containers are protected from a wide range of threats.
To help limit risk and improve security posture, some of the best practices for container security enterprises should follow include:
- Shift security left: To keep up with dynamic threats, enterprises need to integrate security throughout CI\CD pipelines. This means shifting security left and integrating secure practices throughout the software development lifecycle (SDLC) is a must.
- Follow the principle of least privilege: Enterprises take a zero-trust approach to user and application privileges. This means following best practices such as using IAM policies based on the principle of least privilege and limiting, using read-only filesystems, limiting API access, and eliminating or restricting the use of the privileged flag with Docker containers.
- Reduce attack surface: Unused open network ports, libraries, and workloads are potential exploit entryways. To limit risk when running container workloads, enterprises should turn off unused network services, uninstall unused libraries, and decommission workloads that no longer serve a business purpose.
- Only use trusted and secure container images: Public container registries often contain vulnerabilities or, in some cases, malware. Enterprises should only pull container images from trusted repositories to limit their exposure to malicious or vulnerable images.
- Use the right DevSecOps tools: Proactive scanning and monitoring, source composition analysis, and robust threat detection are key aspects of container security. However, traditional security appliances aren’t ideal for container workloads. Therefore, enterprises that want to optimize their security posture need DevSecOps tools built with modern infrastructure in mind.
See Docker Container Security and Kubernetes (K8s) Security for a deeper dive into container security.
Secure Containers with CloudGuard
CloudGuard for Container Security is a fully automated container security platform designed to protect enterprise workloads end-to-end from build through runtime. With CloudGuard, enterprises have a DevSecOps platform that can address modern container security challenges in a way traditional security tools cannot.
For example, with CloudGuard, enterprises gain a container security solution that can:
- Protect Docker containers, K8s clusters, and other container workloads across multi-cloud infrastructure.
- Leverage Admission Controller to enforce the principle of least privilege on all clusters.
- Integrate image security scanning into CI\CD pipelines.
- Find exposed credentials and sensitive data and provide remediation steps.
- Automatically scan container images for vulnerabilities, malware, and weak security configurations.
- Perform real-time threat prevention.
- Automatically deploy security controls.
- Implement robust intrusion detection and threat intelligence.
To learn more about how CloudGuard can help improve enterprise security posture, sign up for a demo led by a cloud security expert. In the demo, you’ll learn how to gain full control and visibility for containers throughout a multi-cloud environment. For a closer look at container security, download our free Container Security Guide.
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