The container is ultimately bound by the host OS’s networking rules. For example, if the host OS only allows traffic inbound from a specific subnet and port, the container cannot override this restriction. In the worst case, this would be the most a given container could do. Second, since an OS ultimately hosts the container, that OS can enforce company and security policies. ![]() This is needed to do the body of work required by the application. Now that we have a better idea of what makes a container different from a virtual machine, how does this solve our three problems?įirst, containers make management easier by letting us write build scripts to create a stable, repeatable representation of the host. In this same way, standardizing the way a software container interacts with its host OS to delegate the responsibility for executing tasks simplifies management of the most crucial part, the application. Containers provided a standard format for moving goods: “You can put whatever you want inside the container so long as it conforms to a standard set of dimensions and can be opened and bolted down in a uniform way.” This simplified the logistical process of moving real-world items. In shipping, there was no standardization, which made transport difficult because you had to figure out how to hold each item on a boat, train, or truck. The notion of a standardized container comes from the shipping industry. Instead, containers rely on an abstraction of an operating system that provides hooks into the host OS using standards and conventions supplied by the container system.ĭocker is the de facto container standard for all practical purposes, but other container technologies do exist. ![]() This may come as a surprise to you, even if you’ve dabbled in containers before. Containers differ from traditional virtual machines in one significant way. There are others, but for simplicity, I will focus on those that are the most relevant to business processes. There are three major problem areas that containers hope to solve: ease of management, size, and speed to start. So when you start a VM, you have to go through the entire boot sequence of a traditional computer. Notably, VMs are huge because an entire OS has to go on them. The operating system has to be maintained, patched, and updated disks have to be managed, and all manner of operational overhead goes into their care and feeding. You gain fine-grained control over an entire virtual computer, as well as all the pitfalls of a whole computer. A virtual machine (VM) is a virtual representation of a computer, all the way from its boot process to loading an entire operating system (OS). ![]() To talk about containers, we have to talk about virtual machines. Infrastructure teams and operations had been leveraging virtual machines with great success for decades, so you may be tempted to think, “isn’t this just a virtual machine?” In spirit, yes in application, no. In 2013, Docker was released, beginning a shift in how we think about hosting applications and managing infrastructure.
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