What does an orchestrator (Kubernetes, Nomad, ECS) do?

An orchestrator is a system that manages containers across a cluster of servers: it starts, stops, scales, and monitors them. It automates everything that is impossible to do manually with dozens of microservices.

#Main tasks of an orchestrator

1. Deploying containers It distributes containers across nodes (servers) itself, choosing where resources are available.
2. Scaling It increases or decreases the number of service instances as load changes.
3. Monitoring and self-healing It tracks the state of containers and automatically restarts ones that have crashed.
4. Load balancing It distributes requests among the running service instances.
5. Configuration and secrets management It stores environment variables, tokens, and passwords and injects them into containers at startup.
6. Zero-downtime updates (rolling updates) It gradually replaces old container versions with new ones without interrupting service.

#Orchestrator examples

• Kubernetes: the most popular, with a mature ecosystem.
• Nomad (HashiCorp): lightweight, simple to configure.
• Amazon ECS / EKS: managed solutions on AWS.

Summary:

An orchestrator is the "operating system" for microservices. It ensures their stable operation, scaling, and automation, freeing the team from the routine of managing containers.