System snapshot i2

During initial use / evaluation of Mender we need to provide the user an easy way to test system updates. The reference environment will be based on Raspbian (MEN-2893) and testing system updates need to be easy on that environment as it will be the main path in getting started.

There are a several ways to generate system updates on the Debian family, where the "golden image" approach is usually the first one users try and the easiest to start with. However our current method is quite time consuming and intricate (move SD cards, dump image, etc.). We have some new ideas. This Epic is about the "snapshot" idea.

Note i1 (MEN-2931) provides the client-side logic to do this.

User value (why)

• Easily test Mender system updates with his own changes during evaluation

Acceptance criteria

• There is a command to "snapshot" the currently running (root file) system on the device
• The result is a rootfs-image Mender Artifact uploaded to the Mender server
• There is progress indicator, ideally with ETA of finished upload
• It works with the onboarding reference environment (MEN-2893) out of the box

Future notes (not required for this Epic)

• It is possible to make this work on any Linux system
• It would be useful to snapshot the whole system into an .img file for provisioning new devices
• Ability to store both .img and Mender Artifact on a separate location like a nearby laptop or Google Cloud bucket for history/future reference
• Note: Snapshotting .img could be a nice standalone tool, independent of Mender (for customizing and extracting images before flashing them to devices)