Add ephemeral lifecycle image, enabling podman support

[BarDweller]

Summary

Podman will set ownership for a volume based on ownership of the first mountpoint it is mounted to, or the executing uid/gid if the mountpoint is absent.

pack runs untrusted builds by running the first step (either detect or analyze depending on selected platform version) as root against a matched lifecycle image. Lifecycle images cannot contain a mountpoint for the workspace as lifecycle images are common across many builds that may not use the same uid/gid.

Thus with podman, pack ends up causing the workspace volume to end up owned by root.

Subsequent mounts of the volume are unable to undo the ownership applied by this initial mount, leading to builds failing against podman as it becomes impossible for the build uid/gid to create or remove files within the workspace directory.

This change introduces an ephemeral lifecycle container, akin to the ephemeral builder image already in use.

The ephemeral lifecycle image adds only the workspace directory to the selected lifecycle image, when a lifecycle image will be in use. The workspace directory is added owned by the current build uid/gid, and the ephemeral lifecycle image is used instead of the chosen lifecycle image for all container invocations that would have used the chosen lifecycle image.

Output

Before

Example errors from the build would indicate permissions/ownership of /workspace to be insufficient for the build to proceed.

[extender (build)]   Removing source code
[extender (build)] unable to invoke layer creator
[extender (build)] unable to remove /workspace/.dockerignore
[extender (build)] unlinkat /workspace/.dockerignore: permission denied

After

Afterwards, builds succeed as expected

Successfully built image '127.0.0.1:5000/bardweller/stilettos'

Documentation

• Should this change be documented?
  • Yes, see #___
  • No

Related

Resolves #___

Updated to swap podman rootless, for just podman, as podman rootful is equally non-functional today

[BarDweller]

This will help with

• File ownership on files copied to the <app> dir are set to root when using Podman #1395

[natalieparellano]

LGTM - thanks for the PR @BarDweller 🙏🏼

[jjbustamante]

@BarDweller I think I am fine with this one, if you can address the comments from Natalie I will merge it on Monday :)

[jjbustamante]

LGTM