If you’re interested in cloud-native technologies and containers, you’ve probably heard of Docker and Kubernetes and are wondering how they work together. Is it Kubernetes versus Docker, Kubernetes plus Docker, or both? 

What’s the distinction between Kubernetes and Docker? 

Docker is a set of software development tools for creating, sharing, and running individual containers, whereas Kubernetes is a system for scaling containerized applications. 

Consider containers to be standardized packaging for microservices that contain all of the required application code and dependencies. Docker is responsible for creating the containers. A container can run on any device, including a laptop, the cloud, local servers, and even edge devices. 

A modern application is made up of numerous containers. Kubernetes is in charge of running them in production. Because containers are simple to replicate, applications can auto-scale: they can expand or contract processing capacities to meet user demands. 

Docker and Kubernetes are two mostly complementary technologies. Docker, on the other hand, offers a system called Docker Swarm for running containerized applications at scale—Kubernetes vs Docker Swarm. Let’s look at how Kubernetes and Docker complement each other and compete. 

What is Docker? 

Docker has become synonymous with containers, just as Xerox is shorthand for paper copies and “Google” is shorthand for internet search. However, Docker is more than just containers. 

Docker is a set of tools that allows developers to create, share, run, and orchestrate containerized applications. 

What is Kubernetes? 

Kubernetes is a container orchestration platform that is open source and used for managing, automating, and scaling containerized applications. Because of its greater flexibility and scalability, Kubernetes is the de facto standard for container orchestration, though Docker Swarm is also an orchestration tool. 

Join us at Linux2Cloud for the on-demand sessions to learn more about Kubernetes and Docker. 

The Top 15 Docker Containers 

Docker is a tool for shipping and running applications that every techie has heard of. With all of the attention it is receiving these days, developers and tech behemoths such as Google are developing services to support it. 

Whether or not you have an immediate need for Docker, here is a list of the 15 most popular Docker containers. 

1. Alpinism 

It is a minimal Alpine Linux image with a package index. It is 5 MB in size and is based on musl libc and BusyBox. The image has access to a much larger package repository than other BusyBox-based images. Alpine Linux is an excellent image base for utilities and production software. 

2. BusyBox 

BusyBox, with on-disk sizes ranging from 1 to 5 Mb (depending on the variant), is an excellent component for creating space-efficient distributions. BusyBox is a small executable that combines many common UNIX utilities. The utilities have fewer options than full-featured GNU; however, the included options function and behave similarly to their GNU counterparts. As a result, BusyBox offers a reasonably comprehensive environment for any small or embedded system. 

3. Nginx 

Nginx is a reverse proxy server, load balancer, and origin server that is open source. It is compatible with Linux, BSD variants, Mac OS X, Solaris, AIX, HP-UX, and other *nix platforms. It also has a Microsoft Windows proof-of-concept port. This one should be used if you are still determining your requirements. It is intended to be a disposable container as well as the foundation for other images. 

4. Ubuntu 

Ubuntu is the most popular operating system for public clouds and OpenStack clouds worldwide. Furthermore, the container platform can scale your containers quickly and securely. 

5. PostgreSQL 

PostgreSQL, also known as “Postgres,” is capable of handling work ranging from single-machine applications to internet-facing applications with multiple users. The image contains numerous environmental variables that are easy to overlook. The only required variable is POSTGRES PASSWORD; the rest are optional. Please keep in mind that the Docker-specific variables will only have an effect if you start the container with an empty data directory; any pre-existing databases will be ignored upon container startup. 

6. Redis 

Redis is a networked, open-source data store with optional durability. The “Protected mode” is turned off by default for easy access via Docker networking. As a result, exposing the port outside your host (for example, with -p on docker run) makes it accessible to anyone without a password. Setting a password (via a configuration file) is thus strongly advised. 

7. Node 

Node.js is a server-side and networking application platform. Javascript applications can be run in the Node.js runtime on Mac OS X, Windows, and Linux without modification. Node.js includes an asynchronous I/O library that supports file, socket, and HTTP communication. Because of HTTP and socket support, Node.js can function as a web server without the need for additional software such as Apache. 

8. Apache 

HTTPd Apache is a Web server application that was instrumental in the early development of the internet. This image only contains Apache HTTPd with the upstream defaults. There is no PHP installed, but it should be simple to extend. If you want PHP with Apache HTTPd, look at the PHP image and look for the -apache tags. Add a Dockerfile to the project to run an HTML server, where public-HTML/ is the directory containing all HTML. 

9. Python 

Modules, exceptions, dynamic typing, high-level data types, and classes are all built into Python. It can also be used as an extension language in applications that require a programmable interface. It is portable and works on a variety of Unix variants, including Mac OS X and Windows 2000 and later. Many simple, single-file projects may necessitate assistance in writing a complete Dockerfile. In such cases, you can use the Python Docker image to run a Python script. 

10. MongoDB 

MongoDB is an open-source database program that uses schemata and JSON-like documents. The MongoDB server in the image operates on the standard MongoDB port, 27017, and connects via Docker networks, just like a remote MongoDB 

11. MySQL 

MySQL has established itself as a leading database for web-based applications, supporting a wide range of personal projects and websites. It is simple to start a MySQL instance: -e MYSQL ROOT PASSWORD=my-secret-pw -d mysql:tag $ docker run -name some-mysql -e MYSQL ROOT PASSWORD=my-secret-pw -d mysql . 

12. Memcached 

Memcached is a system for distributed memory caching. Its APIs provide a large hash table distributed across multiple machines. When the table is full, older data is purged in the least recently used order. Memcached applications typically layer requests and additions into RAM before exiting to a slower backing store. 

13. Traefik 

Traefik is an HTTP reverse proxy and load balancer that allows for the rapid deployment of microservices. It automatically integrates with the existing Docker infrastructure and dynamically configures itself. The only configuration step should be to point Traefik to your orchestrator. 

14. MariaDB 

MariaDB Server is a well-known open-source database server developed by MySQL developers. It is simple to start a MariaDB instance with the most recent version: $ docker run –detach –name some-mariadb –env MARIADB USER=example-user –env MARIADB PASSWORD=my cool secret –env MARIADB ROOT PASSWORD=my-secret-pw mariadb:latest \sor: $ docker network create some-network $ docker run –detach –network some-network –name some-mariadb –env MARIADB USER=example-user –env MA 

15. RabbitMQ 

RabbitMQ is a free and open-source message broker that uses the Advanced Message Queuing Protocol. It saves data based on the “Node Name,” which is usually the hostname. In Docker, we should explicitly specify -h/-hostname for each daemon so that the user does not get a random hostname and can keep track of the data. 

Bottom Line 

Docker Swarm and Kubernetes are both production-grade container orchestration platforms, though their strengths differ. 

Docker Swarm, also known as Docker in swarm mode, is the most straightforward orchestrator to deploy and manage. It may be a good option for a company that is just getting started with container production. Swarm covers 80% of all use cases with only 20% of the complexity of Kubernetes.