Docker Swarm Introduction
Docker Swarm enables to take multiple nodes and collect there resources into one cluster or swarm.
They work in a Manager-Worker Architecture fashion.
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Cluster management integrated with Docker Engine - Docker CLI allows you to create a swarm of Docker Engines where you can deploy your application. No additional software needed.
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Decentralized design - Docker Engine handles specialization at runtime, allowing you to deploy an entire swarm from a single disk image.
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Declarative service model - Allows you to define the desired state of the various services in your application stack.
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Scaling - You can scale up or down and the swarm manager automatically adapts by adding or removing tasks to maintain the desired state.
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Desired state reconciliation - The swarm manager constantly monitors the cluster state. It will recognize any difference between the actual state and the desired state and act to reconcile the two.
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Multi-host networking - Swarm manager will automatically assign addresses to containers on an overlay network when the container is initialized or updated.
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Service Discovery - Each service in the swarm is assigned a unique DNS name.
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Load Balancing - Ports for services can be exposed to an external load balancer and internally the swarm lets you configure how to distribute service containers between your worker nodes.
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Secure by default - Each worker node in the swarm enforces TLS mutual authentication and encryption between itself and the nodes.(Both option self signed certificates or custom certificates)
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Rolling Updates - Swarm lets you control the delay between service deployments to different sets of nodes. If something goes wrong, you can roll back to a previous state.