Fix copying root

[kvaps]

Fixes #960

Description

This PR updates otiai10/copy module from v1.0.2 to v1.6.0.
Adds option to not copying ignored paths for CopyFileOrSymlink which solves two problems at once:

• Allows copying root (/)
• Avoid leaking docker credentials using COPY command while building the image.

It might need rebase after merging #1725.
This branch includes both fixes: kvaps:fix-copying-root-and-ownership; compiled docker images:

ghcr.io/kvaps/kaniko-executor:v1.6.0-fix
ghcr.io/kvaps/kaniko-executor:v1.6.0-fix-debug
ghcr.io/kvaps/kaniko-warmer:v1.6.0-fix

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes unit tests
• Adds integration tests if needed.

See the contribution guide for more details.

Reviewer Notes

• The code flow looks good.
• Unit tests and or integration tests added.

Release Notes

Describe any changes here so maintainer can include it in the release notes, or delete this block.

- Add additional check for ignored files on COPY
- Support copying root (`/`) of image

[kvaps]

PR rebased to v1.7.0, new docker images with this change prepared:

ghcr.io/kvaps/kaniko-executor:v1.7.0
ghcr.io/kvaps/kaniko-executor:v1.7.0-debug
ghcr.io/kvaps/kaniko-warmer:v1.7.0

source code of fork in master branch:
https://github.com/kvaps/kaniko/

[jasondamour]

@kvaps any movement on this? Do you need help w last mile?

[aaron-prindle]

@kvaps would you be able to rebase the PR here? Would like to get this in if possible, thanks!

[aaron-prindle]

Submitted this PR here #2592 which rebases the changes here. Closing and moving the conversation over that PR. Feel free to re-submit, re-open, discuss, etc. if you would like to own this going in - thanks!