From 665ac6d3df9cc0b1638b24598d2f5b628bf38a5c Mon Sep 17 00:00:00 2001 From: Victoria Bialas Date: Tue, 3 Jan 2017 18:51:07 -0800 Subject: [PATCH] update swarm worker node concept description incorporated review comments from Misty re-worded topic titles and added to description of node fixed links for services and tasks incorporated more comments Signed-off-by: Victoria Bialas --- engine/swarm/key-concepts.md | 41 +++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/engine/swarm/key-concepts.md b/engine/swarm/key-concepts.md index 2a25b35e5d..ffb1ae915f 100644 --- a/engine/swarm/key-concepts.md +++ b/engine/swarm/key-concepts.md @@ -7,37 +7,40 @@ title: Swarm mode key concepts This topic introduces some of the concepts unique to the cluster management and orchestration features of Docker Engine 1.12. -## Swarm +## What is a swarm? The cluster management and orchestration features embedded in the Docker Engine -are built using **SwarmKit**. Engines participating in a cluster are -running in **swarm mode**. You enable swarm mode for the Engine by either +are built using **SwarmKit**. Docker engines participating in a cluster are +running in **swarm mode**. You enable swarm mode for an engine by either initializing a swarm or joining an existing swarm. -A **swarm** is a cluster of Docker Engines where you deploy -[services](key-concepts.md#Services-and-tasks). The Docker Engine CLI includes the commands for -swarm management, such as adding and removing nodes. The CLI also includes the -commands you need to deploy services to the swarm and manage service -orchestration. +A **swarm** is a cluster of Docker engines, or _nodes_, where you deploy +[services](key-concepts.md#services-and-tasks). The Docker Engine CLI and API +include commands to manage swarm nodes (e.g., add or remove nodes), and deploy +and orchestrate services accross the swarm. -When you run Docker Engine outside of swarm mode, you execute container -commands. When you run the Engine in swarm mode, you orchestrate services. +When you run Docker without using swarm mode, you execute container +commands. When you run the Docker in swarm mode, you orchestrate services. You can run swarm services and standalone containers on the same Docker instances. -## Node +## What is a node? -A **node** is an instance of the Docker Engine participating in the swarm. +A **node** is an instance of the Docker engine participating in the swarm. You can also think of this as a Docker node. You can run one or more nodes on a single physical computer or cloud server, but production swarm deployments typically include Docker nodes distributed across multiple physical and cloud machines. To deploy your application to a swarm, you submit a service definition to a **manager node**. The manager node dispatches units of work called -[tasks](key-concepts.md#Services-and-tasks) to worker nodes. +[tasks](key-concepts.md#services-and-tasks) to worker nodes. Manager nodes also perform the orchestration and cluster management functions -required to maintain the desired state of the swarm. Manager nodes elect a single leader to conduct orchestration tasks. +required to maintain the desired state of the swarm. Manager nodes elect a +single leader to conduct orchestration tasks. -**Worker nodes** receive and execute tasks dispatched from manager nodes. By -default manager nodes are also worker nodes, but you can configure managers to -be manager-only nodes. The agent notifies the manager node of the current -state of its assigned tasks so the manager can maintain the desired state. +**Worker nodes** receive and execute tasks dispatched from manager nodes. +By default manager nodes also run services as worker nodes, but you can +configure them to run manager tasks exclusively and be manager-only +nodes. An agent runs on each worker node and reports on the tasks assigned to +it. The worker node notifies the manager node of the current state of its +assigned tasks so that the manager can maintain the desired state of each +worker. ## Services and tasks @@ -82,4 +85,4 @@ the service. ## What's next? * Read the [swarm mode overview](index.md). -* Get started with the [swarm mode tutorial](swarm-tutorial/index.md). \ No newline at end of file +* Get started with the [swarm mode tutorial](swarm-tutorial/index.md).