Docker Alternatives

Docker transformed application deployment by introducing portable containers, facilitating rapid scalability for businesses. However, concerns about resource inefficiencies and security emerged. Kubernetes emerged as a leading alternative, leveraging the Container Runtime Interface (CRI) to reduce Docker dependency. Meanwhile, Docker's evolving subscription policies prompted developers to seek alternatives across macOS, Windows, and Linux platforms. Despite Docker's innovations—enabling easy container creation from source code and seamless deployment across various environments—Kubernetes deprecated its runtime in version 1.20. This shift highlighted Kubernetes' flexibility, accommodating a broader range of runtimes while emphasizing the value of diverse container management solutions in the evolving tech landscape.

What is Docker?

Docker is a platform that enables developers and sysadmins to create, deploy, and run applications with containers.

We have talked about Docker in detail here.

Docker Architecture

Docker follows Client-Server architecture, which includes three main components that are Docker Client, Docker Host, and Docker Registry. Let's take a look at these components.

The Docker client is responsible for interacting with the Docker daemon, which handles the heavy lifting of building, running, and distributing Docker containers. These containers are created from images that are stored in a Registry.

Let's take a more detailed look at the different components:

Docker daemon

It is a daemon process that runs on the host operating system. It is responsible for running containers to manage docker services. It manages the Docker objects such as images, containers, networking, and storage.

Docker Client

It uses commands and REST APIs to communicate with the Docker Daemon. When a client runs any docker command on the docker client terminal, the client terminal sends these docker commands to the Docker daemon for processing.

Docker Objects

A lot of different objects work together to run an application inside Docker. An application requires objects such as - Docker Images for the application code, Docker Containers to run the application, and Docker Registries to save and download Docker Images.

Let's have a look at them as well.

Images

It is a lightweight, executable package that consists of everything needed to run an application: code, libraries, third-party dependencies, environment variables, and configurations.

Containers

It is the place where Docker runs an image. You can think of it in this way as well for simplicity: Images become containers when they run on Docker Engine.

Docker Registries

It is a storage and distribution system for Docker images which are tagged and have a name.

Docker Features / Benefits

Docker provides a lot of benefits -

Improved and seamless container portability

Containers are seamlessly portable because a container creates an executable package of software that is abstracted away from the host operating system. That is why Docker can run uniformly and consistently across any platform or cloud.

Even lighter weight and more granular updates

Docker containers are lightweight as compared to traditional applications that run on VMs because, in containers, we don't have to load the OS. Updates to a docker image are much easier than updates on VMs.

Automated container creation

Containers can be instantly created, destroyed, stopped, or started with ease. This makes scaling the infrastructure quick & easy.

Container versioning

Maintenance of multiple versions of an application is very systematic. This makes auditing and trailing easier.

Container reuse

A container created to run a Python application can be reused multiple times for other python dependent applications.

Shared container libraries

Logic and code created for one container can be reused with zero to little modifications for other application containers.

Docker Alternatives

Let's take a brief overview of the Docker alternatives -

Cloud Foundry

It is a docker alternative that provides a highly efficient, modern model for cloud-native application delivery on top of Kubernetes.

Podman

It is a daemon-less, open-source, Linux native tool designed as a docker alternative to make it easy to find, run, build, share, and deploy applications using Open Containers Initiative (OCI) Containers and Container Images.

LXD

It supplies a system daemon that applications can use to access LXC and has a template distribution system to enable faster container creation and operation.

Containerd

It is a docker alternative with a container runtime that manages the lifecycle of a container on a physical or virtual machine. Think of it as a process that creates, starts, stops, and destroys containers apart from being also able to pull container images from container registries, mount storage, and enable networking for a container.

Buildah

It is an open source docker alternative that is Linux-based, primarily used to build Open Container Initiative (OCI)-compatible containers, meaning the containers are compatible with Docker and Kubernetes as well.

BuildKit

It is a proposal to separate the docker build experience into a separate project, allowing different users to collaborate on the underlying technology and reuse and customize it in different ways.

Kaniko

It is an open-source tool that allows users to create container images in their Dockerfile without root access.

RunC

It is a CLI tool for spawning and running containers on Linux according to the OCI specification.

CoreOS rkt

It is a containerization software engine for running application workloads in isolation from the underlying infrastructure.

Hyper-V Containers

Under the Hyper-V containers principle, multiple container instances run concurrently on a host; however, each container runs inside of a highly optimized virtual machine and effectively gets its kernel.

Kubernetes

It is an open-source container orchestration system for automating software deployment, scaling, and management.

LXC Linux Containers

It is an operating-system-level virtualization method for running multiple isolated Linux systems on a control host using a single Linux kernel.

OpenVZ

It is an operating-system-level virtualization technology for Linux. It allows a physical server to run multiple isolated operating system instances, called containers, virtual private servers, or virtual environments. OpenVZ is similar to Solaris Containers and LXC.

Vagrant

It is an open-source docker alternative product for building and maintaining portable virtual software development environments.

Virtual Box

It is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation.