Limitations of non-isolated builds
What are non-isolated builds?
In Lix, only builds done on Linux with sandbox = true and a functioning
pasta-path are isolated from the rest of the system, all other builds are
considered non-isolated to some degree.
For example, running Lix with Pasta disabled makes the host network visible to fixed-output derivations, reducing isolation somewhat.
Clean termination of non-isolated builds
Non-isolated builds may not terminate cleanly in all cases due to limitations in Lix's process management.
This occurs when a build keeps the build log file descriptor open past the end of the actual build. A common cause of this are background tasks that aren't properly terminated before the main build process exits, for example: HTTP servers run as part of a test suite.
See issue #1018 for an example.
The only solution is to manually terminate leftover processes in your derivation, including during failure scenarios.