Containers for Dummies

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36 Containers For Dummies, HPE and Docker Special Edition These materials are © 2017 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. » Docker Community Edition (CE) is the freely available version of Docker. Docker CE is often used for development purposes, as it doesn't offer the support options available with Docker EE. In this way, Docker CE is like many other open-source projects. There is a free tier, but as you need support, you can either turn to the community or choose from among vendor-provided options. Planning Docker Resource Requirements Each OS carries with it separate requirements that you need to consider. Plus, just like any other application environment, Docker containers need RAM, compute, and storage resources in order to operate. On the RAM and CPU front, there's not a lot of difference in how you plan resources, but there may be a big difference in how those resources are used. With virtual machines, resources are started up and they stay up for long periods of time. With containers, they may live for a long time, but more often than not, they sur- vive for a short period of time to carry out their singular func- tion and then they're killed. They consume and release resources very rapidly. The single-service, short-lived, lightweight nature of Docker containers means that you can probably dial in your resource requirements in a more exact way than you could before, but this will take a bit of trial and error on your part as you work out what your containers need. There is also the question of failure domain to consider. Underly- ing hardware will fail. So, as you architect your environment, be careful about putting too much on one server. You may be better off buying a few more servers that are a bit less powerful than buying just one or two monster servers. This will help ensure high availability. Although it's getting better, storage is not as straightforward as it is in the world of the virtual machine. As you plan your storage requirements, make sure that you understand how your existing or planned storage will connect to your Docker cluster. We'll talk more about Docker storage in Chapter 5.

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