Kubernetes versus Docker is a frequently debated subject in the cloud computing field.
Whether you come from a non-technical background and need a brief introduction or if you need to make a business decision, we hope that this in-depth comparison clarifies the situation once and for all.
We must look past the frenzy that has surrounded both Kubernetes and Docker. It is essential to understand what these terms entail before building your business on top of them.
What is Kubernetes?
Kubernetes (also known as K8s) is a container orchestration system designed for production use.
It is an open-source cluster management system created by three Google workers during the summer of 2014 and quickly expanded to become the first project to be contributed to the Cloud Native Computing Foundation (CNCF).
It is essentially an open-source toolkit for developing a fault-tolerant, scalable platform for automating and centrally managing containerized applications. You can manage your containerized application more effectively with Kubernetes.
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Types of Kubernetes
Kubernetes is a massive project with a ton of code and features. Kubernetes’ core function is container orchestration. This includes ensuring that all containers that run various workloads are scheduled to operate real or virtual machines.
The containers must be effectively packed while adhering to the restrictions of the deployment environment and cluster configuration. Furthermore, Kubernetes must monitor all operating containers and replace dead, inactive, or otherwise unstable ones.
Kubernetes uses Docker to execute images and manage containers. K8s may, however, utilize alternative engines, such as rkt from CoreOS.
The platform itself may be implemented in practically any infrastructure – a local network, a server cluster, a data center, or any cloud – public (Google Cloud, Microsoft Azure, AWS, and so on), private, hybrid, or a mix of these techniques.
It is worth noting that Kubernetes allows automated container deployment and replica over a set of servers. It includes a variety of features that may be thought of as:
- A platform for containers
- A platform for microservices
- A mobile cloud platform, among other things
What is Docker?
Docker is a simple containerization system that has garnered traction in the cloud and application packaging communities.
It is an open-source platform for automating application deployment in compact and lightweight containers. It sandboxes processes into programmable virtual environments by leveraging several Linux kernel features such as cgroups, AppArmor profiles, namespaces, etc.
Although this notion of ‘virtual container’ is not new, it has recently gained traction with industry heavyweights such as Microsoft, HP, Red Hat, SaltStack, IBM, VMware, and others throwing their support behind Docker, a relative newcomer.
Docker is also attracting the attention of start-ups. Shippable, CoreOS, and Drone.io are examples of start-ups that are structured to deliver Docker-based services.
Red Hat Enterprise Linux 7 already includes it as a significantly supported container format.
Why is Kubernetes so popular?
Kubernetes takes into account the majority of the operational requirements for application containers. The following are the top ten reasons why Kubernetes is so popular:
- Auto-scaling feature support
- Real-world use cases available
- Multi-cloud support (hybrid cloud)
- Container health monitoring
- Compute resource management
- Effective persistent storage
- Largest open source project in the world
- Great community support
- Robust container deployment
- High availability by cluster federation
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Why is Docker popular?
The main reasons for Docker’s appeal are its speed, simplicity of use, and the fact that it is mainly free. It is even reported to be equivalent in terms of performance to KVM.
A container-based strategy, in which programs operate in isolation and without the need for a separate operating system, can save significant amounts of hardware resources.
Experts in the industry have begun to see it as hardware multi-tenancy for applications. Rather than hundreds of VMs running on each server, what if thousands of hardware-isolated apps could be run?
Docker is used to executing software packages known as “containers.” A container is a standardized unit of software that bundles up code and all its dependencies so that the program may be moved from one computing environment to another quickly and reliably.
Containers are the “fastest-growing cloud-enabling technology”* because they accelerate software delivery while lowering operating costs.
It is easier to write software. It is simpler to deploy — in your data center or your favorite cloud. It also demands less hardware and support to run.
While container technology has been around for decades, Docker makes it work for the enterprise by providing the fundamental functionality that businesses need in a container platform and best-practice services to assure success.
Containers may be used for both legacy programs and new development.
Existing mission-critical programs may frequently be “containerized” with little or no change. As a result, there are immediate savings in infrastructure, improved security, and decreased labor.
Because programmers are just targeting a single platform rather than a multitude of servers and clouds, new development occurs more quickly. There is less code to write. There will be less testing—faster delivery.
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Features of Kubernetes
Service discovery and load balancing: Kubernetes includes a feature that provides each container with its IP address and a unique DNS name, which may be used to balance the load on them.
Planning & placement: The placement of the containers on the node is a crucial aspect influencing the decision depending on the resources required and other constraints.
Autoscaling: Vertical scaling of programs is automatically activated via the command line based on CPU consumption.
Self-repair: This is a unique Kubernetes feature that will reboot the container instantly if it fails. If a node fails, the containers on the other nodes are replaced or re-planned. If the containers do not respond to the checkups, you can disable them.
Storage orchestration: This Kubernetes feature allows users to connect the network storage system as a local file system.
Batch execution: Kubernetes supports both batch and continuous integration workloads and the replacement of failed containers.
Deployments and automatic rollbacks: During the modifications for the Kubernetes-hosted application, it gradually monitors its health to ensure that it does not terminate all instances at once, and it does an automated rollback only in the event of failure.
Configuration management and Secrets: In Kubernetes, all classified information, such as keys and passwords, is kept in the Secrets module. These Secrets are beneficial when configuring the application without having to rebuild the image.
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Features of Docker
Here are the essential features of Docker:
- Isolated environments for managing your applications
- Application agility
- Developer productivity
- Operational efficiencies
- Easy modeling
- Version control
- Placement/affinity
Kubernetes vs Docker: Let the Bout Begin
Although both ringleaders provide much of the same functions, there are substantial differences in how they work. Some of the essential elements in the Kubernetes vs Docker comparison are mentioned here.
Installation and cluster configuration
Docker
Installing Docker is as straightforward as installing any other application from your operating system’s package management system. With Swarm, all that is necessary is to deploy a node and instruct it to join the cluster.
In addition to its simplicity of use, Swarm provides versatility by allowing any new node to adopt an existing cluster as either a manager or a worker and smoothly boost or demote nodes between the two roles.
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Kubernetes
Kubernetes needs many manual settings to connect its components including flannel and the Docker engine.
Installation instructions range from one operating system to the next and from one provider to the next.
Kubernetes also requires advanced knowledge of the cluster setup, such as the IP addresses of the nodes, the function that each node will play, and the overall number of nodes.
Verdict
Docker is easy and fast to install and configure while Kubernetes takes some work to get up and running, so Docker wins this.
Container setup
Docker
The Swarm API offers many of the same features as Docker, although it doesn’t cover all of its commands.
It supports numerous Docker-compatible tools; nonetheless, if the Docker API lacks a particular action, there is no straightforward method to get around it using Swarm.
Kubernetes
Kubernetes has its client, API, and YAML specifications that differ from the conventional Docker counterparts.
Needless to say, neither Docker Compose nor Docker CLI may be used to have containers defined. YAML and Command definitions have to be rebuilt when switching platforms.
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Verdict
Docker’s functionality is provided and limited by the Docker API whereas YAML, API, and client definitions are unique to Kubernetes which gives it the edge.
Scalability
Docker
Docker Swarm could deploy containers much more quickly than Kubernetes, even in huge groups at high cluster fill stages, enabling quick response times to demand-based scaling.
A single update command can be used to start new replicas.
Kubernetes
In comparison, Kubernetes is more of an all-in-one platform for distributed systems.
Its complexity arises from providing uniform API sets and solid assurances about the status of the cluster, which reduces the speed of scaling and container deployment.
Verdict
Docker has faster scaling and container deployment even in massive clusters while Kubernetes provides strong guarantees to cluster states at the expense of speed.
Load balancing
Docker
Load balancing is incorporated into Docker Swarm. All containers in a group interact with a shared network which permits connections from any node to any container.
Connection requests sent to any node in the Swarm are internally routed to a node hosting an instance of the service.
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Kubernetes
When container pods are configured as services, Kubernetes allows for much of the load balancing notion.
Each service is accessible via a specific set of pods and policies that would enable the configuration of load balancer pods that can contact the service without regard for IP addresses.
Verdict
Docker has more automated internal load balancing through any node in the cluster whereas Kubernetes requires manual service configuration to enable load balancing, so Docker wins this bout.
Container updates and rollbacks
Docker
The Docker Swarm container updates are performed by instructing the scheduler to use a fresh image rather than the existing one.
The upgrade may then be sent out in phases, avoiding service disruption and allowing for rollback if something goes wrong.
Kubernetes
Kubernetes controls the update process, gradually checking service health to maintain availability while applying changes to one pod at a time, preventing unscheduled downtime.
Verdict
Docker processes scheduling to maintain services while updating whereas Kubernetes progressively updates and service health monitoring through the update, so it’s a tie here.
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Data volumes
Docker
Data volumes in Docker are folders that are shared by one or more containers. Volumes can be produced independently or in conjunction with containers, and many containers can share them.
Data volumes are also retained even if the containers that use them are removed. Volumes, on the other hand, are exclusively local to the node on which they are generated.
The Docker engine can be integrated with volume plugins for creating global volumes.
Kubernetes
Volumes in Kubernetes seem like an abstraction that allows containers to exchange data inside the same pod.
The volumes have an explicit lifespan; they are generated and deleted in tandem with the pods they contain. The Volumes function in the same way that any other directory accessible to containers in the same pod does.
Kubernetes also supports external data volume managers for data transmission across pods.
Verdict
Docker shares simple local volumes while Kubernetes volumes are shared within pods.
Networking
Docker
Docker Swarm creates a multiple host network structure that links every node of cluster containers. Several networks originating from inter-container can be manually set up.
TLS authentication using certificates is also used to automatically secure connections between nodes.
Kubernetes
Container networking is frequently accomplished with flannel in Kubernetes. Containers are linked together via a virtual network and announced using etc.
TLS authentication is also feasible, but it necessitates the generation and installation of certificates on all nodes.
Verdict
Docker is preferred here because it automatically configures TLS authentication and container networking while Kubernetes TLS authentication requires manual configuration for security.
Service Discovery
Docker
Docker Swarm container networking makes service discovery much more accessible. Every container joins the cluster-wide ingress network overlay just at the time of deployment.
It enables containers to interact with one another using virtual private IP addresses and service names regardless of the underlying hosts.
Kubernetes
For service discovery, Kubernetes uses etcd and manually specified services. When containers start, they can announce themselves and contribute important information to the distributed key-value store.
For improved connectivity, an optional cluster add-on for the DNS server is also available.
Verdict
Docker services are discoverable throughout the cluster network while Kubernetes Containers can be defined as easily discoverable services, so Kubernetes wins this one.
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When You Should Use Kubernetes
When a project has expanded considerably, it necessitates one of the following reasons, for which K8 stands up to the challenge:
Near-perfect uptime: Kubernetes’ self-healing functionality allows resource-hungry apps to continue running regardless of how many errors your stack experiences resulting from the hunger.
When trying out different containerization vendors: Because it works with virtually all vendors (varying degrees of difficulty), using K8 as the orchestrator allows you to explore the field. No vendor may claim your contract unless they meet your SLA after the trial period.
When unsure of growth potential: When apps horizontally scale, K8 automatically splashes resources at them.
When You Should Use Docker
There are instances when you would want to host your apps using Docker and its tools. Let us look at a few of these examples;
When K8 is not an option: Due to skill shortages, API inconsistencies, and expenses, all utilization may be funneled into Docker and its tools. Docker Swarm may completely replace K8 for orchestration.
When just starting: When applications are still in RAD growth loops, you won’t need to link Docker with any orchestrator. At this moment, speed outweighs perseverance.
When creating CLI apps: Docker was initially designed to house CLI programs, and for these, you’ll always find efficiencies that increase productivity.
When You Should Use Them Together
Kubernetes and Docker work well together as a complementary orchestra. One example is the sluggish throughput we complained about with Kubernetes’ on-the-fly deployment and container health procedures.
The combination works well when you have both the budget and the talent to support timeless applications. You will not be able to encounter unusual downtime sources since the communities will assist you.
It is also prudent to note that both suppliers have left sockets and cracks through which portions of each other might bind for improved performance.
Kompose by K8 is a Docker Compose adaption. This means that utilizing both tools was and continues to be the norm.
This puts our stalemate to a peaceful conclusion. Usage points are entirely subjective. However, you will not be relying solely on Kubernetes.
For higher performance than other containerization technologies, connect it with Docker and a data security provider.
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Pros and Cons
Kubernetes Pros
- Pods provide for a simple service organization.
- Google created it, bringing years of necessary industry knowledge to the table.
- The most active community among container orchestration technologies
- Provides a wide range of storage solutions, including on-premises SANs and public clouds
- Follows the principles of immutable infrastructure
Kubernetes Cons
- Migrating to statelessness necessitates a significant amount of work.
- According to the Docker API’s availability, there is limited functionality.
- The installation/configuration procedure is quite complicated.
- Existing Docker CLI and Compose tools are incompatible.
- Setup of manual clusters deployment and automated horizontal scaling is complicated.
Docker Pros
- Provides a more efficient and straightforward initial setup.
- Synchronizes with and complements current Docker technologies.
- Allows you to detail your application’s lifetime.
- Docker allows users to easily track their container versions to investigate inconsistencies between previous versions.
- Configuration is simple; connect with Docker Compose.
- Docker provides a fast-paced environment that quickly boots up a virtual machine and allows a program to execute in a virtual environment.
- The documentation contains every piece of information.
- Provides easy and quick configuration to help your business grow.
- It makes sure that the application is isolated.
Docker Cons
- There is no storage option.
- Has a subpar monitoring option
- Inactive nodes are not automatically rescheduled.
- The setup of automated horizontal scaling is complicated.
- All activities must be carried out in CLI.
- Basic infrastructure management
- Multiple instances must be handled manually.
- Support is required for additional tools used in production, such as monitoring, healing, and scaling.
- Complex manual cluster deployment
- There is no assistance for health checks.
- Docker is a for-profit SaaS provider. Many essential components, such as Docker Engine and Docker Desktop, are closed-source.
Similarities between Kubernetes and Docker?
Well, if “Kubernetes is container orchestration,” and “Docker is containers” why then should anyone ask “Should I use Docker or Kubernetes?”.
In reality, the two tools complement one other and support the implementation of cloud-native or microservice architectures.
Docker is most commonly employed in the early stages of a containerized application. It facilitates the construction and deployment of the application’s container(s).
Docker can meet the fundamental demands of the application’s lifecycle management in instances when the application’s design is very straightforward.
Kubernetes is used when an application is divided into many microservices, each with its lifecycle and operational requirements.
Kubernetes is not used to generate application containers. It requires a container platform to run, the most common being Docker. Kubernetes integrates with and leverages a vast toolset designed for and around containers in its operations.
Containers built using Docker or any of its equivalents may be managed, scaled, and relocated by Kubernetes, managing failover and system health.
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Wrapping it up
Kubernetes can handle more extensive needs with greater complexity, but Docker Swarm provides a simple, quick-to-implement alternative.
Docker Swarm is popular among developers who seek quick deployments and ease of use. Simultaneously, Kubernetes is used in production environments by several high-profile online companies that run popular programs.
Some of the same services can be run by Kubernetes and Docker Swarm, although they may require somewhat different approaches to critical features.
By understanding Kubernetes vs Docker and comparing their functionalities, you can make an informed decision on which technology to choose for container orchestration.
