Container Orchestrators
Containerization has become a norm in the Cloud Native Development world today, when everyone is moving a step closer towards microservices-based technology. Containers being lightweight and easily scalable, are deployed in large numbers in a real-life application. While it is practical to manage the life-cycle of a container through a command line interface (CLI), it becomes impractical to do so for a swarm of containers. There-in lies the need for an orchestration tool to manage the various aspects of the life-cycle of containers.
Container Orchestrators manage provisioning, scaling and load balancing, health monitoring, resource allocation, moving between hosts and decommissioning of container resources. Kubernetes (from Google) is the most popular container orchestrating tool used in the industry today. Few others like Docker Swarm (from Docker Inc.) and Mesos (from Apache) are also popular tools. While Docker Swarm manages only Docker containers, Kubernetes can handle and manage a variety of containers including Docker.
Most of the orchestrators work on the principle of one master and multiple compute nodes. In Kubernetes, the master node is responsible for exposing the API and scheduling deployments and managing the overall cluster. Each worker node runs a collection of container runtimes (known as Pods in the Kubernetes world) and an agent that communicates with the master node. The worker nodes also run components that are responsible for logging, service discovery, health monitoring and other functions.
The key attributes of an orchestrator are scalability, availability, security and portability. An application architected on microservices can be auto-scaled across different nodes , wherein the orchestrator manages the scale. Each component of the cluster is configured for high-availability by managing a minimum set of containers that serve the purpose of handling failure. Load balancers and health check are ingrained in the orchestrator design to ensure high availability. Security is enforced through secure API endpoints and secure authentication mechanisms. Container orchestrators can be configured on a wide variety of platforms enabling users to move workloads easily from one deployment to another, including a hybrid environment.
There is a lot going on in the container world, but this technology also has it’s own challenges to overcome. These challenges are more cultural in nature than technical. Technically, there are security, network-related and service discovery issues that prop-up when containerization is espoused. However, culturally it is a paradigm shift that the organization must adapt to.
Listen to this O’Reilly podcast with Mesosphere’s Michael Hausenblas to learn more about container orchestrators and tips to overcome prevalent challenges:
