Software update: Docker 0.8

Docker is an open source developer tool that can be used to create installation packages. It puts the application including all the components it depends on in a virtual container that can run on almost any Linux machine. This week, version 0.8 of Docker became available. According to the developers, the emphasis has been on quality and not so much on adding a lot of new functionality. In addition to many bug fixes, there is now a version for OS X and a new driver for the btrfs file system.

Docker 0.8: Quality, new builder features, btrfs, OSX support

Today we are happy to introduce Docker 0.8, with a focus on Quality and 3 notable features: new builder instructions, a new BTRFS storage driver, and official support for Mac OSX. You can see the full Changelog on the repository, and read below for details on each feature.

This release is special in several ways:

First, this is the first Docker release where features take the backseat to quality: dozens and dozens of bugfixes, performance boosts, stability improvements, code cleanups, extra documentation and improved code coverage – that’s the primary feature in Docker 0.8. We still have ways to go, and there are still many open bugs! But we are making progress and will continue to focus on Quality until it becomes a defining characteristic of Docker.

Second, this release marks the beginning of a new release cadence, which we hope you will find simpler and clearer. It’s a very simple cycle:

• One release per month. Every first week of the month, we release a new version of Docker. For example, in the first week of March we will release 0.9.
• Master always works. We only merge patches which we consider ready to be released. And we only release what’s in master. This makes it very easy to test upcoming features or distribute a “bleeding edge” version of docker. Simply build from master and you will get the current release candidate.
• Not feature based. Release dates are not linked to any specific features. If a feature is merged before the release date, it gets released. Otherwise, the next merge window is only a month away.
• simple numbering. We follow the Linux convention for numbering versions. The first digit indicates a major change in the project’s lifecycle. For example, 1.0 indicates that the project is considered ready for production use. The second digit indicates regularly scheduled releases. The third digit is reserved for hotfixes, stability backports etc.

Lastly, this release marks the beginning of our support for platforms other than Linux on 64bit x86. With Docker 0.8 we are focusing on Mac support – but expect us to start supporting more and more platforms over the next few releases. As many of you have pointed out, “run anywhere” is only useful if you can actually, you know… run anywhere.