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translating---geekpi
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# Docker swarm mode - Adding worker nodes tutorial
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Let us expand on what we started with CentOS 7.2 several weeks ago. In this [guide][1], we learned how to initiate and start the native clustering and orchestration functionality built into Docker 1.12\. But we only had our manager node and no other workers. Today, we will expand this.
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I will show you how to add non-symmetrical nodes into the swarm, i.e. a [Fedora 24][2] that will sit alongside our CentOS box, and they will both participate in the cluster, with all the associated fancy loadbalancing and whatnot. Of course, this will not be trivial, and we will encounter some snags, and so it ought to be quite interesting. After me.
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### Prerequisites
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There are several things we need to do before we can successfully join additional nodes into the swarm. One, ideally, all nodes should be running the same version of Docker, and it should be at least 1.12 in order to support native orchestration. Like CentOS, Fedora does not have the latest built in its repo, so you will need to manually [add and install][3] the right software version, either manually or using the Docker repository, and then fix a few dependency conflicts. I have shown you how to do this with CentOS, and the exercise is identical.
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Moreover, all your nodes will need to be able to communicate with one another. There will have to be routing and firewall rules in places so that the managers and workers can talk among them. Otherwise, you will not be able to join nodes into the swarm. The easiest way to work around problems is to temporarily flush firewall rules (iptables -F), but this may impair your security. Make sure you fully understand what you're doing, and that you create the right rules for your nodes and ports.
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Error response from daemon: Timeout was reached before node was joined. The attempt to join the swarm will continue in the background. Use the "docker info" command to see the current swarm status of your node.
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You need to have the same Docker images available on your hosts. In our previous tutorial, we created an Apache image, and you will need to do the same on your worker nodes, or distribute the created images. If you do not do that, you will encounter errors. If you need help setting up Docker, please read my [intro guide][4] and the [networking tutorial][5].
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```
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7vwdxioopmmfp3amlm0ulimcu \_ websky.11 my-apache2:latest
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localhost.localdomain Shutdown Rejected 7 minutes ago
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"No such image: my-apache2:lat&"
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```
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### Let's get started
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So we have our CentOS box up and running, and it's spawning containers successfully. You are able to connect to the services using host ports, and everything looks peachy. At the moment, your swarm only has the manager.
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### Join workers
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To add new nodes, you will need to use the join command. But you first need to discover what token, IP address and port you must provide on the worker nodes for them to authenticate correctly against the swarm manager. Then execute (on Fedora).
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```
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[root@localhost ~]# docker swarm join-token worker
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To add a worker to this swarm, run the following command:
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docker swarm join \
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--token SWMTKN-1-0xvojvlza90nrbihu6gfu3qm34ari7lwnza ... \
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192.168.2.100:2377
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```
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If you do not fix the firewall and routing rules, you will get timeout errors. If you've already joined the swarm, repeating the join command will create its own noise:
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```
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Error response from daemon: This node is already part of a swarm. Use "docker swarm leave" to leave this swarm and join another one.
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```
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If ever in doubt, you can leave the swarm and then try again:
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```
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[root@localhost ~]# docker swarm leave
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Node left the swarm.
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docker swarm join --token
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SWMTKN-1-0xvojvlza90nrbihu6gfu3qnza4 ... 192.168.2.100:2377
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This node joined a swarm as a worker.
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```
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On the worker node, you can use docker info to check the status:
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```
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Swarm: active
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NodeID: 2i27v3ce9qs2aq33nofaon20k
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Is Manager: false
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Node Address: 192.168.2.103
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Likewise, on the manager:
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Swarm: active
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NodeID: cneayene32jsb0t2inwfg5t5q
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Is Manager: true
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ClusterID: 8degfhtsi7xxucvi6dxvlx1n4
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Managers: 1
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Nodes: 3
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Orchestration:
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Task History Retention Limit: 5
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Raft:
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Snapshot Interval: 10000
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Heartbeat Tick: 1
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Election Tick: 3
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Dispatcher:
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Heartbeat Period: 5 seconds
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CA Configuration:
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Expiry Duration: 3 months
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Node Address: 192.168.2.100
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```
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### Create or scale services
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Now, we need to see if and how Docker distributes the containers between the nodes. My testing shows a rather simplistic balancing algorithm under very light load. Once or twice, Docker did not try to re-distribute running services to new workers, even after I tried to scale and update them. Likewise, on one occasion, it created a new service entirely on the worker node. Maybe it was the best choice.
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New service created entirely on the worker node.
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After a while, there was some re-distribution of containers for existing services between the two, but it took some time. New services worked fine. This is an early observation only, so I cannot say much more at this point. For now, this is a good starting point to begin exploring and tweaking.
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Load balancing kicks in after a while.
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### Conclusion
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Docker is a neat little beast, and it will only continue to grow bigger, more complex, more powerful, and of course, more elegant. It is only a matter of time before it gets eaten by a big, juicy enterprise. When it comes to its native orchestration, the swarm mode works quite well, but it takes more than just a few containers to fully tap into the power of its algorithms and scalability.
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My tutorial shows how to add a Fedora node to a cluster run by a CentOS box, and the two worked fine side by side. There are some questions around the loadbalancing, but this is something I will explore in future articles. All in all, I hope this was a worthwhile lesson. We've tackled some prerequisites and common problems that you might encounter when trying to setup a swarm, we fired up a bunch of containers, and we even briefly touched on how to scale and distribute the services. And remember, 'tis is just a beginning.
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Cheers.
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--------------------------------------------------------------------------------
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作者简介：
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My name is Igor Ljubuncic. I'm more or less 38 of age, married with no known offspring. I am currently working as a Principal Engineer with a cloud technology company, a bold new frontier. Until roughly early 2015, I worked as the OS Architect with an engineering computing team in one of the largest IT companies in the world, developing new Linux-based solutions, optimizing the kernel and hacking the living daylights out of Linux. Before that, I was a tech lead of a team designing new, innovative solutions for high-performance computing environments. Some other fancy titles include Systems Expert and System Programmer and such. All of this used to be my hobby, but since 2008, it's a paying job. What can be more satisfying than that?
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From 2004 until 2008, I used to earn my bread by working as a physicist in the medical imaging industry. My work expertise focused on problem solving and algorithm development. To this end, I used Matlab extensively, mainly for signal and image processing. Furthermore, I'm certified in several major engineering methodologies, including MEDIC Six Sigma Green Belt, Design of Experiment, and Statistical Engineering.
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I also happen to write books, including high fantasy and technical work on Linux; mutually inclusive.
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Please see my full list of open-source projects, publications and patents, just scroll down.
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For a complete list of my awards, nominations and IT-related certifications, hop yonder and yonder please.
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-------------
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via: http://www.dedoimedo.com/computers/docker-swarm-adding-worker-nodes.html
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作者：[Igor Ljubuncic][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://www.dedoimedo.com/faq.html
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[1]:http://www.dedoimedo.com/computers/docker-swarm-intro.html
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[2]:http://www.dedoimedo.com/computers/fedora-24-gnome.html
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[3]:http://www.dedoimedo.com/computers/docker-centos-upgrade-latest.html
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[4]:http://www.dedoimedo.com/computers/docker-guide.html
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[5]:http://www.dedoimedo.com/computers/docker-networking.html
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@ -0,0 +1,149 @@
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# Docker Sawrm 模式 - 添加 worker 节点教程
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让我们继续几周前在 CentOS 7.2 中开始的工作。 在本[指南][1]中，我们学习了如何初始化以及启动 Docker 1.12 中内置的本地集群以及编排功能。但是我们只有管理节点还没有其他 worker 节点。今天我们会展开这个。
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我将向你展示如何将不对称节点添加到 Sawrm 中，也就是 [Fedora 24][2] 将与 CentOS 相邻，它们都将加入到集群中，还有相关很棒的负载均衡等等。当然这并不是微不足道的，我们会遇到一些障碍，所以它应该是非常有趣的。
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### 先决条件
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在将其他节点成功加入 Swarm 之前，我们需要做几件事情。理想情况下，所有节点都应该运行相同版本的 Docker，为了支持本地编排，它的版本至少应该为 1.12。像 CentOS 一样，Fedora 内置的仓库没有最新的构建，所以你需要手动或者使用 Docker 仓库手动[添加并安装][3]正确的版本，并修复一些依赖冲突。我已经向你展示了如何在 CentOS 中操作，练习是相同的。
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此外，所有节点都需要能够相互通信。这就需要有正确的路由和防火墙规则，这样管理和 worker 节点才能互相通信。否则，你无法将节点加入 Swarm 中。最简单的解决方法是临时刷新防火墙规则 （iptables -F），但这可能会损害你的安全。请确保你完全了解你正在做什么，并为你的节点和端口创建正确的规则。
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守护进程的错误响应：节点加入之前已超时。尝试加入 Swarm 的请求将在后台继续进行。使用 “docker info” 命令查看节点的当前 Swarm 状态。
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你需要在主机上提供相同的 Docker 镜像。在上一个教程中我们创建了一个 Apache 映像，你需要在你的 worker 节点上执行相同操作，或者分发创建的镜像。如果你不这样做，你会遇到错误。如果你在设置 Docker 上需要帮助，请阅读我的[介绍指南][4]和[网络教程][5]。
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```
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7vwdxioopmmfp3amlm0ulimcu \_ websky.11 my-apache2:latest
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localhost.localdomain Shutdown Rejected 7 minutes ago
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"No such image: my-apache2:lat&"
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```
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### 现在开始
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现在我们有一台 CentOS 机器并启动了，并成功创建了容器。你可以使用主机端口连接到服务，这一切都看起来很好。目前，你的 Swarm 只有管理节点。
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### 加入 workers
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要添加新的节点，你需要使用 join 命令。但是你首先必须提供令牌、IP 地址和端口，以便 woker 节点能正确地对 Swarm 管理器进行身份验证。接着执行（在 Fedora 上）：
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```
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[root@localhost ~]# docker swarm join-token worker
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要将 worker 添加大这个 Swarm 中，运行下面的命令：
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docker swarm join \
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--token SWMTKN-1-0xvojvlza90nrbihu6gfu3qm34ari7lwnza ... \
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192.168.2.100:2377
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```
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如果你不修复防火墙和路由规则，你会得到超时错误。如果你已经加入了 Swarm，重复 join 命令会收到错误：
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```
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Error response from daemon: This node is already part of a swarm. Use "docker swarm leave" to leave this swarm and join another one.
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```
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如果有疑问，你可以离开 Swarm，然后重试：
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```
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[root@localhost ~]# docker swarm leave
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Node left the swarm.
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docker swarm join --token
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SWMTKN-1-0xvojvlza90nrbihu6gfu3qnza4 ... 192.168.2.100:2377
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This node joined a swarm as a worker.
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```
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在 worker 节点中，你可以使用 “docker info” 来检查状态：
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```
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Swarm: active
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NodeID: 2i27v3ce9qs2aq33nofaon20k
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Is Manager: false
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Node Address: 192.168.2.103
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Likewise, on the manager:
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Swarm: active
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NodeID: cneayene32jsb0t2inwfg5t5q
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Is Manager: true
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ClusterID: 8degfhtsi7xxucvi6dxvlx1n4
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Managers: 1
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Nodes: 3
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Orchestration:
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Task History Retention Limit: 5
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Raft:
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Snapshot Interval: 10000
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Heartbeat Tick: 1
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Election Tick: 3
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Dispatcher:
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Heartbeat Period: 5 seconds
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CA Configuration:
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Expiry Duration: 3 months
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Node Address: 192.168.2.100
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```
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### 创建或缩放服务
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现在，我们需要看下 Docker 是否以及如何在节点间分发容器。我的测试展示了一个在非常轻的负载下相当简单的平衡算法。试了一两次之后，即使在我尝试缩放并更新之后，Docker 也没有将运行的服务重新分配给新的 worker。同样，有一次，它在 worker 节点上创建了一个新的服务。也许这是最好的选择。
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在新的 worker 节点上创建完整新的服务。
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过了一段时间，两个容器之间的现有服务有一些重新分配，但这需要一些时间。新服务工作正常。这只是一个前期观察，所以我现在不能说更多。现在是开始探索和调整的新起点。
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负载均衡过了一会工作了。
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### 总结
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Docker 是一只灵巧的小野兽，它只会继续扩大，更复杂，更强大，当然也更优雅。它被一个大企业吃掉只是一个时间问题。当它涉及本地编排时，Swarm 模式运行得很好，但是它不仅仅需要几个容器来充分利用其算法和可扩展性。
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我的教程展示了如何将 Fedora 节点添加到由 CentOS 运行的群集中，并且两者能并行工作。关于负载平衡还有一些问题，但这是我将在以后的文章中探讨的。总而言之，我希望这是一个值得记住的教训。我们已经解决了在尝试设置 Swarm 时可能遇到的一些先决条件和常见问题，同时我们启动了一堆容器，我们甚至简要介绍了如何缩放和分发服务。要记住，这只是一个开始。
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干杯。
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--------------------------------------------------------------------------------
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作者简介：
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|
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我是 Igor Ljubuncic。现在大约 38 岁，已婚但还没有孩子。我现在在一个大胆创新的云科技公司做首席工程师。直到大约 2015 年初，我还在一个全世界最大的 IT 公司之一中做系统架构工程师，和一个工程计算团队开发新的基于 Linux 的解决方案，优化内核以及攻克 Linux 的问题。在那之前，我是一个为高性能计算环境设计创新解决方案的团队的技术领导。还有一些其他花哨的头衔，包括系统专家、系统程序员等等。所有这些都曾是我的爱好，但从 2008 年开始成为了我的付费工作。还有什么比这更令人满意的呢？
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从 2004 年到 2008 年间，我曾通过作为医学影像行业的物理学家来糊口。我的工作专长集中在解决问题和算法开发。为此，我广泛地使用了 Matlab，主要用于信号和图像处理。另外，我得到了几个主要的工程方法学的认证，包括 MEDIC 六西格玛绿带、试验设计以及统计工程学。
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我也开始写书，包括奇幻类和 Linux 上的技术性工作。彼此交融。
|
||||
|
||||
要查看我开源项目、出版物和专利的完整列表，请滚动到下面。
|
||||
|
||||
有关我的奖项，提名和 IT 相关认证的完整列表，请稍等一下。
|
||||
|
||||
-------------
|
||||
|
||||
|
||||
via: http://www.dedoimedo.com/computers/docker-swarm-adding-worker-nodes.html
|
||||
|
||||
作者：[Igor Ljubuncic][a]
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.dedoimedo.com/faq.html
|
||||
[1]:http://www.dedoimedo.com/computers/docker-swarm-intro.html
|
||||
[2]:http://www.dedoimedo.com/computers/fedora-24-gnome.html
|
||||
[3]:http://www.dedoimedo.com/computers/docker-centos-upgrade-latest.html
|
||||
[4]:http://www.dedoimedo.com/computers/docker-guide.html
|
||||
[5]:http://www.dedoimedo.com/computers/docker-networking.html
|
||||
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Reference in New Issue
Block a user