Which version of docker has built-in swarm?

Starting from the "docker 1.12.0" version, swarm is built-in; swarm is a platform used to manage docker clusters. It is developed using the go language. Starting from the "1.12.0" version, "Docker Swarm" has included In the Docker engine, the service discovery tool is already built-in, so there is no need to configure Etcd or Consul for service discovery configuration.

The operating environment of this tutorial: linux7.3 system, docker version 19.03, Dell G3 computer.

Which version of docker has built-in swarm

Swarm is a platform launched by Docker to manage docker clusters. Almost all development is done in GO language

Docker Swarm and Docker Compose is the same as Docker's official container orchestration project, but the difference is that Docker Compose is a tool to create multiple containers on a single server or host, while Docker Swarm can create container cluster services on multiple servers or hosts. , for the deployment of microservices, obviously Docker Swarm will be more suitable.

Starting from Docker 1.12.0 version, Docker Swarm has been included in the Docker engine (docker swarm), and has built-in service discovery tools. We do not need to configure Etcd or Etcd as before. Consul is used for service discovery configuration.

As can be seen from the above figure, Swarm is a typical master-slave structure, which elects managers by discovering services. The manager is the central management node. Agents run on each node to accept the unified management of the manager. The cluster will automatically elect manager nodes in a distributed manner through the Raft protocol without the need for additional discovery service support, avoiding single-point bottlenecks. It also has built-in DNS. load balancing and integrated support for external load balancing mechanisms.

Extended knowledge

Docker Swarm working principle

1) Docker Engine client

docker service create: We use docker service create This command creates a service.

2) swarm manager

API: This request is received directly by the API of Swarm manager, receives the command and creates the service object.

orchestrator: Create a task for the service.

allocater: Assign an IP address to this task.

dispatcher: allocate tasks to specified nodes.

scheduler: Issue the specified command to the node.

3) Worker node: After receiving the manager task, run the task

container: Create the corresponding container.

worker: Connect to the scheduler to check the assigned tasks

executor: execute the tasks assigned to the worker node

Service: is a copy, which can be understood as a task , a task is a container.

swarm manager: It distributes this copy to three available work nodes.

container: The actual docker container to run the application.

task: The name of the work task is the service name followed by .1 and so on according to the number.

Recommended learning: "docker video tutorial"

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