Rapid VM builds - Capstan

Rapid VM builds - Capstan

Capstan is a tool for rapidly building and running your application on OSv. Capstan is as simple and fast as using Docker for creating containers, but the result is a complete virtual machine image that will run on any hypervisor with OSv support. A typical Capstan image is only 6-7MB larger than your application itself, and adds about 3 seconds to the build time.

If you haven’t made your application available as a “virtual appliance” because of the complexity of doing it on a conventional OS, Capstan could be just what you need. From fast horizontal scaling to demo and evaluation images, virtual appliance delivery of your application is now fast thanks to the low overhead of Capstan.

Install Capstan

See here

Running a Capstan-enabled application

Because a Capstan-enabled application is a complete, first-class virtual machine image, you can run it in your private or public cloud using your administration tools of choice. No separate container environment is required.

Capstan includes a capstan run command, to easily run your images locally for testing, under VirtualBox or KVM.

See for yourself

Capstan-enabling an application

Making a VM image from your application with Capstan requires adding one additional step in the build. A single file called Capstanfile defines the base image to be used, the files to be included, and any arguments to be passed to the application. Check out Capstanfile documentation for the format of that file.

The OSv project maintains a public repository of pre-built Capstan base images, or you can maintain your own Capstan repository on Amazon Web Services or in Git.


Like OSv itself, Capstan is distributed under the 3-clause BSD license.