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* Added important disambiguation to swarm mode This really needs to be added, I had no idea people gave up on docker/swarm because of a misunderstanding, but it's common enough we need to clarify it. From Docker's public #swarm slack channel: ``` andrew grosser 4:45 PM Hey @channel I am about to give a talk in San Francisco to a bunch of devops experts about swarm using my ingress and reverse proxy controller https://github.com/sfproductlabs/roo and one of the organizers said swarm was deprecated, is that so? It's so much easier than kubernetes, I can't imagine losing it. sfproductlabs/roo A zero config distributed edge-router & reverse-proxy (supporting multiple letsencrypt/https hosts). No dependencies. Stars 40 Language Go <https://github.com/sfproductlabs/roo|sfproductlabs/roo>sfproductlabs/roo | Apr 9th | Added by GitHub 4:46 Is there something we don't know? james_wells 4:48 PM As of the most recent official Docker release, no Swarm is still officially part of Docker... They merely added native support for Kubernetes andrew grosser 4:49 PM 🙏 Phew, is there an EOL? 4:49 Thanks @james_wells 4:50 I think they going to get the grenade launchers out if I can't answer these questions james_wells 4:51 PM Now that is a good question and my guess is that no, there is no plan to remove it, at least before Docker 3. andrew grosser 4:52 PM Amazing thx, I have a system that is a startups dream and is personally saving me more than 10x using swarm, so praying it stays bmitch:docker: 4:53 PM Classic container deployed swarm is deprecated (I believe). Swarm mode that's integrated into the engine is still being developed by Mirantis with no EOL set. 4:53 So if someone says swarm is deprecated, make sure to ask "which swarm" they are referring to. andrew grosser 4:54 PM Ok thanks @bmitch 4:54 Think that's a brand thing we'll need to help change james_wells 4:56 PM @bmitch I am not sure I understand what you are sayin there. Could you please explain the differences bmitch:docker: 4:56 PM See the disambiguation section: https://hub.docker.com/r/dockerswarm/swarm james_wells 4:57 PM Excellent. Thank you sir andrew grosser 5:02 PM Thanks bmitch:docker: 5:02 PM See also this link where they are getting ready to archive the standalone swarm, aka classic swarm. https://github.com/docker/classicswarm/issues/2985#issuecomment-640486361 justincormackjustincormack Comment on #2985 Why have all issues been closed? The vast majority of issues were from 5 years ago when it was being actively developed, and the recent ones were all mistakes for swarmkit, other than some issues I resolved. Many were issues in components or Moby or other software and may be resolved. It is GitHubs (reasonable) recommendation that you close issues and PRs before archiving a repository so that people know they are not being worked on, and I was also looking to see if anyone came forward to say that they were still working on things or, indeed, actively using Swarm Classic. <https://github.com/docker/classicswarm|docker/classicswarm>docker/classicswarm | Jun 8th | Added by GitHub james_wells 5:08 PM That is really unfortunate... Kubernetes is simply too expensive IMNSHO, Swarm is nice and lightweight. andrew grosser 5:08 PM Both the different swarms point to the same point in the documentation in the disambiguation @bmitch bmitch:docker: 5:09 PM Swarm mode, aka swarmkit is alive and well. andrew grosser 5:10 PM Whoa I can see why they were confused bmitch:docker: 5:10 PM If you type docker swarm init you are not running classic swarm andrew grosser 5:11 PM Can someone inside docker add this to the swarm docs page? I think it's important 5:12 I think something talking about 2014 was EOLd but this is still current and alive would help. bmitch:docker: 5:12 PM Docker themselves isn't maintaining it, that team went to Mirantis, so someone over there would need to submit the PR andrew grosser 5:12 PM OK, could I? bmitch:docker: 5:13 PM Docs are in GitHub andrew grosser 5:13 PM Thanks ``` * Minor edit to the wording to clarify the diff * Minor update Co-authored-by: Usha Mandya <47779042+usha-mandya@users.noreply.github.com>
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| Docker Engine swarm mode overview | docker, container, cluster, swarm | Swarm mode overview |
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To use Docker in swarm mode, install Docker. See installation instructions for all operating systems and platforms.
Current versions of Docker include swarm mode for natively managing a cluster of Docker Engines called a swarm. Use the Docker CLI to create a swarm, deploy application services to a swarm, and manage swarm behavior.
Docker Swarm mode is built into the Docker Engine. Do not confuse Docker Swarm mode with Docker Classic Swarm{:target="blank" rel="noopener" class=""} which is no longer actively developed.
Feature highlights
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Cluster management integrated with Docker Engine: Use the Docker Engine CLI to create a swarm of Docker Engines where you can deploy application services. You don't need additional orchestration software to create or manage a swarm.
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Decentralized design: Instead of handling differentiation between node roles at deployment time, the Docker Engine handles any specialization at runtime. You can deploy both kinds of nodes, managers and workers, using the Docker Engine. This means you can build an entire swarm from a single disk image.
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Declarative service model: Docker Engine uses a declarative approach to let you define the desired state of the various services in your application stack. For example, you might describe an application comprised of a web front end service with message queueing services and a database backend.
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Scaling: For each service, you can declare the number of tasks you want to run. When you scale up or down, 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 node constantly monitors the cluster state and reconciles any differences between the actual state and your expressed desired state. For example, if you set up a service to run 10 replicas of a container, and a worker machine hosting two of those replicas crashes, the manager creates two new replicas to replace the replicas that crashed. The swarm manager assigns the new replicas to workers that are running and available.
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Multi-host networking: You can specify an overlay network for your services. The swarm manager automatically assigns addresses to the containers on the overlay network when it initializes or updates the application.
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Service discovery: Swarm manager nodes assign each service in the swarm a unique DNS name and load balances running containers. You can query every container running in the swarm through a DNS server embedded in the swarm.
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Load balancing: You can expose the ports for services to an external load balancer. Internally, the swarm lets you specify how to distribute service containers between nodes.
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Secure by default: Each node in the swarm enforces TLS mutual authentication and encryption to secure communications between itself and all other nodes. You have the option to use self-signed root certificates or certificates from a custom root CA.
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Rolling updates: At rollout time you can apply service updates to nodes incrementally. The swarm manager lets you control the delay between service deployment to different sets of nodes. If anything goes wrong, you can roll back to a previous version of the service.
What's next?
Swarm mode key concepts and tutorial
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Learn swarm mode key concepts.
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Get started with the Swarm mode tutorial.
Swarm mode CLI commands
Explore swarm mode CLI commands