That's a good example. I was at HAProxyConf in November, and Willy showed HAProxy running on a solar-powered device to demonstrate its efficiency. Disclosure: I'm part of the HAProxy team.

For those interested, the device is a breadbee. (https://github.com/breadbee/breadbee).

If we forget about it, it might be because it gives us so little issue. Software you don't think about is a treat :)

I agree. I'm used to saying this to the rest of the development team: we are very critical about our own code because we receive all the bug reports, which tends to give us a feeling that there's always something to fix. But seeing it another way, with hundreds of thousands of deployments, having 2-3 issues a week is ridiculously low and means that the vast majority of deployments will never face a bug in their life.

It still poses us a problem which is that users don't upgrade. For example 1.6 is still routinely met in production despite having been unsupported for 2 years, and sometimes with 3 or 4 years of uptime because users forget about it or just don't want to risk an upgrade for no perceived benefit. I can't blame them honestly, as long as they upgrade before reporting problems or asking for help!