Using Mender for local updates
So much for the theory. In the next two sections of this chapter, I want to demonstrate how the principles I have talked about so far work in practice. For these examples, I will use Mender. Mender uses a symmetric A/B image update mechanism, with a fallback in the event of a failed update. It can operate in standalone mode for local updates, or in managed mode for OTA updates. I will begin with standalone mode.
Mender is written and supported by mender.io (https://mender.io). There is much more information about the software in the documentation section of the website. I will not delve deeply into the configuration of the software here since my aim is to illustrate the principles of software updates. Let's begin with the Mender client.
Building the Mender client
The Mender client is available as a Yocto meta layer. These examples use the Dunfell release of the Yocto Project, which is the same one that we used in Chapter 6, Selecting a Build...