In which practical ways can virtualization enhance your development environment ?

Question

Practical uses of virtualization in software development are about as diverse as the techniques to achieve it.

Whether running your favorite editor in a virtual machine, or using a system of containers to host various services, which use cases have proven worth the effort and boosted your productivity, and which ones were a waste of time ?

I'll edit my question to provide a summary of the answers given here. Also it'd be interesting to read about about the virtualization paradigms employed too, as they have gotten quite numerous over the years.

Edit : I'd be particularly interested in hearing about how people virtualize "services" required during development, over the more obvious system virtualization scenarios mentioned so far, hence the title edit.

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Summary of answers :

• Development Environment

  • Allows encapsulation of a particular technology stack, particularly useful for build systems

• Testing

  • Easy switching of OS-specific contexts
  • Easy mocking of networked workstations in a n-tier application context

Answer 1

We deploy our application into virtual instances at our host (Amazon EC2). It's amazing how easy that makes it to manage our test, QA and production environments.

Version upgrade? Just fire up a few new virtual servers, install the software to be tested/QA'd/used in production, verify the deployment went well, and throw away the old instances.

Need more capacity? Fire up new virtual servers and deploy the software.

Peak usage over? Just dispose of no-longer-needed virtual servers.

Answer 2

We're testing the way our application behaves on a new machine after every development iteration, by installing it onto multiple Windows virtual machines and testing the functionality. This way, we can avoid re-installing the operating system and we're able to test more often.

Answer 3

We needed to test the setup of a collaborative network application in which data produced on some of the nodes was shared amongst cooperating nodes on the network in a setup with ~30 machines, which was logistically (and otherwise) prohibitive to deploy and set up. The test runs could be long, up to 48 hours in some cases. It was also tedious to deploy changes based on the results of our tests because we'd have to go around to each workstation and make the appropriate changes, which was a manual and error-prone process involving several tired developers.

One approach we used with some success was to deploy stripped-down virtual machines containing the software to be tested to various people's PCs and run the software in a simulated data-production/sharing mode on those PCs as a background task in the virtual machine. They could continue working on their day-to-day tasks (which largely consisted of producing documentation, writing email, and/or surfing the web, as near as I could tell) while we could make more productive use of the spare CPU cycles without "harming" their PC configuration. Deployment (and re-deployment) of the software was simplified, since we could essentially just update one image and re-use it on all the PCs. This wasn't the entirety of our testing, but it did make that particular aspect a lot easier.

Answer 4

We put the development environments for older versions of the software in virtual machines. This is particularly useful for Delphi development, as not only do we use different units, but different versions of components. Using the VMs makes managing this much easier, and we can be sure that any updated exes or dlls we issue for older versions of our system are built against the right stuff. We don't waste time changing our compiler setups to point at the right shares, or de-installing and re-installing components. That's good for productivity.

It also means we don't have to keep an old dev machine set up and hanging around just-in-case. Dev machines can be re-purposed as test machines, and it's no longer a disaster if a critical old dev machine expires in a cloud of bits.

Answer 5

Virtualization is used mainly for various server uses where I work:

1. Web servers - If we create a new non-production environment, the servers for it tend to be virtual ones so there is a virtual dev server, virtual test server, etc.

2. Version control and QA applications - Quality Center and SVN are run on virtual servers. The SVN box also runs CC.Net for our CI here.

There may be other uses but those seem to be the big ones at the moment.