Open source container-based virtualization is ready for prime time—or ready enough, at least, to start making money. This week, Docker took the first steps toward monetizing its virtualization platform by rolling out a slew of new services and features, including a private-repository service priced starting at $7 per month.

From its debut as an open source project in March 2013 until this week, all of the Docker platform—which delivers applications inside software containers that are abstracted from the host operating system through the method known as container-based virtualization—was free. The Docker team made clear last month, however, that that would change, with developers planning to introduce optional services that users could purchase in order to support long-term growth of the platform.

The first such service, announced March 19, is private Docker repositories. Those repositories will be hosted on Docker's website along with their public counterparts, but with the paid private-repository service, users can restrict access to specific collaborators. Docker developers envision this feature as a way for programmers building container-based applications to collaborate more effectively prior to releasing their apps into the wild.

Alongside this new service, Docker has added usability features to its repository system. These include automation tools, as well as new ways to categorize and browse repositories. It has added a notification service, too, that sends users alerts by emails when certain events occur within their repositories. For now, that service remains free, if basic, since users can configure only a few specific types of events to generate notifications.

To be sure, Docker is still growing up. Widespread adoption remains beyond the horizon. But the private-repository service is a first step in what looks to be a committed effort on the part of Docker developers to monetize container-based virtualization while keeping the code open source, and the usability enhancements will not hurt in generating more interest in the software and expanding its user base.