Some error occur when upgrading bionic-base to jammy-base

[zhoufenqin]

From Jammy stack.toml and Bionic stack.toml, I found the uid is different.

In jammy stack, the uid is difference between build and runtime phase, and the final /workspace dir is generated by build user, there is no permission for runtime user to do some write operations in the folder.

So when we migrate bionic stack to jammy stack, we may meet some errors. E.g. In the spring boot project, if there are some code like Files.copy(Paths.get(source), Paths.get(destination)), then it will be blocked.

So why the uid change between the build and runtime phase, and is there any guide to migrate bionic stack to jammy stack smoothly?

Expected Behavior

Current Behavior

Possible Solution

Steps to Reproduce

Motivations

[robdimsdale]

The UID is different between the build and run phases to improve security and confirm with the upstream specification: https://github.com/buildpacks/rfcs/blob/main/text/0085-run-uid.md

We don't have a migration guide specifically, but other than this issue there aren't any buildpack-specific changes. More generally, users should be aware of the fact that there are different packages on Jammy vs Bionic, but that's true outside of using Buildpacks, too.