Since the revolutionization of the concept by Docker in 2013, containers have become a mainstay in application development. Their speed and resource efficiency make them ideal for a DevOps environment as they allow developers to run software faster and more reliably, no matter where it is deployed. With containerization, it’s possible to move and scale several applications across clouds and data centers.
However, this scalability can eventually become an operational challenge. In a scenario where an enterprise is tasked with the efficient running of several containers carrying multiple applications, container orchestration becomes, not just an option, but a necessity.
Contents
- What Is Container Orchestration?
- How Does Container Orchestration Work?
- How Does Container Orchestration Work With Kubernetes?
- How Does Container Orchestration Work With Docker?
- How Does Container Orchestration Work With Other Platforms?
- What Is the Best Tool for Container Orchestration?
What Is Container Orchestration?
Container orchestration is the automated process of managing, scaling, and maintaining containerized applications. Containers are executable units of software containing application code, libraries, and dependencies so that the application can be run anywhere. Container orchestration tools automate the management of several tasks that software teams encounter in a container’s lifecycle, including the following:
- Deployment
- Scaling and load balancing/traffic routing
- Networking
- Insights
- Provisioning
- Configuration and scheduling
- Allocation of resources
- Moving to physical hosts
- Service discovery
- Health monitoring
- Cluster management
How Does Container Orchestration Work?
There are different methodologies that can be applied in container orchestration, depending on the tool of choice. Container orchestration tools typically communicate with YAML or JSON files that describe the configuration of the application. Configuration files guide the container orchestration tool on how and where to retrieve container images, create networking between containers, store log data, and mount storage volumes.
The container orchestration tool also schedules the deployment of containers into clusters and automatically determines the most appropriate host for the container. After a host has been determined, the container orchestration tool manages the container’s lifecycle using predefined specifications provided in the container’s definition file.
Container orchestration tools can be used in any environment that runs containers. Several platforms offer container orchestration support, and they include Kubernetes, Docker Swarm, Amazon Elastic Container Service (ECS), and Apache Mesos.
How Does Container Orchestration Work With Kubernetes?
Kubernetes is an open-source container orchestration platform that is considered the industry standard. The Google-backed solution allows developers and operators to deliver cloud services, either as Platform-as-a-Service (PaaS), or Infrastructure-as-a-Service (IaaS). It’s a highly declarative solution, allowing developers to declare the desired state of their container environment through YAML files. Kubernetes then establishes and maintains that desired state.
The following are the main architecture components of Kubernetes:
Nodes
A node is a worker machine in Kubernetes. It may be virtual or physical, depending on the cluster. Nodes receive and perform tasks assigned from the Master Node. They also contain the necessary services to run pods. Each node is composed of a kubelet, a container runtime, and a kube-proxy.
Master Node
This node controls all the worker nodes and is the origin of all assigned tasks. It does this through the control pane, which is the orchestration layer that exposes the API and interfaces to define, deploy, and manage the lifecycles of containers.
Cluster
A cluster represents the master node and multiple worker nodes. Clusters combine these machines into a single unit to which containerized applications are deployed. The workload is then distributed to various nodes, making adjustments as nodes are added or removed.
Pods
Pods are the smallest deployable units of computing that can be created and managed in Kubernetes. Each Pod represents a collection of containers packaged together and deployed to a node.
Deployments
A deployment provides declarative updates for Pods and ReplicaSets. It enables users to designate how many replicas of a Pod they want running simultaneously.
How Does Container Orchestration Work With Docker?
Docker, also an open-source platform, provides a fully integrated container orchestration tool known as Docker Swarm. It can package and run applications as containers, locate container images from other hosts, and deploy containers. It is simpler and less extensile than Kubernetes, but Docker provides the option of integration with Kubernetes for organizations that want access to Kubernetes’ more extensive features.
The following are the main architectural components of Docker Swarm:
Swarm
A swarm is a cluster of Docker hosts which run in swarm mode and manage membership and delegation while also running swarm services.
Node
A node is the docker engine instance included in a swarm. It can be either a manager node or a worker node. The manager node dispatches units of work called tasks to worker nodes. It’s also responsible for all orchestration and container management tasks like maintaining cluster state and service scheduling. Worker nodes receive and execute tasks.
Services and Tasks
A service is the task definition that needs to be executed on the nodes. It defines which container images to use and which commands to execute inside running containers.
A task carries a container alongside the commands to run inside the container. Once a task is assigned to a node, it cannot move to another node.
How Does Container Orchestration Work With Other Platforms?
Although Docker and Kubernetes are leading the pack when it comes to container orchestration, other platforms are capitalizing on their open-source software to provide competition.
Red Hat OpenShift is an open-source enterprise-grade hybrid platform that provides Kubernetes functionalities to companies that need managed container orchestration. Its framework is built on a Linux OS that allows users to automate the lifecycles of their containers.
Google Kubernetes Engine is powered by Kubernetes and enables users to easily deploy, manage, and scale Docker containers on Google Cloud.
Other platforms like Apache Mesos and Amazon ECS have developed their own container tools which allow users to run containers while ensuring security and high scalability.
Examples of Container Orchestration
Container orchestration provides a number of benefits for organizations, but what do those benefits look like in real-world work situations? We included a couple of common orchestration examples below:
First, consider a large e-commerce platform that experiences heavy traffic during the holiday season. In the past, that platform would have to manually provision additional servers to handle the increased holiday load, which is a time-consuming and error-prone process. With container orchestration, the platform can use an auto-scaling feature that automatically provisions additional containers as traffic increases and scales back down when traffic decreases. That way, increased traffic for the holiday rush can die down in January once everyone buys, returns, and exchanges their items.
Second, consider a company that has a website, a mobile app, and a back-end processing system that all runs on different servers in different environments. In the past, managing these different applications and environments would require a lot of manual effort and coordination. With container orchestration, the company can use a single platform to manage all of its containers and environments, allowing them to easily deploy, manage, and scale its applications across different environments. This allows the company to more easily adopt new technologies and streamline its development process.
What Is the Best Tool for Container Orchestration?
When choosing the best container orchestration tool for an organization, several factors have to be taken into consideration. These factors vary across different tools. With a tool like Mesos, for instance, the software team’s technical experience must be taken into account as it is more complex than simple tools like Swarm. Organizations also have to consider the number of containers to be deployed, as well as application development speed and scaling requirements.
With the right tools and proper resource management, container orchestration can be a valuable approach for organizations looking to achieve improved productivity and scalability.