Change user/group creation to use flags to adduser/useradd to enforce it
being a system user. Use system user defaults that auto-create a
matching group. These changes allow us to remove all group creation
code, and in doing so we also removed the code that finds available uid,
gid integers and use post-creation query to gather the system-generated
uid and gid.
The only added complexity is that today distros don't auto-create
subordinate ID ranges for a new ID if it is a system ID, so we now need
to handle finding a free range and then calling the `usermod` tool to
add the ranges for that ID. Note that this requires the distro supports
the `-v` and `-w` flags on `usermod` for subordinate ID range additions.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
pkg/ is a collection of utility packages used by the Docker project without being specific to its internals.
Utility packages are kept separate from the docker core codebase to keep it as small and concise as possible.
If some utilities grow larger and their APIs stabilize, they may be moved to their own repository under the
Docker organization, to facilitate re-use by other projects. However that is not the priority.
The directory pkg is named after the same directory in the camlistore project. Since Brad is a core
Go maintainer, we thought it made sense to copy his methods for organizing Go code :) Thanks Brad!
Because utility packages are small and neatly separated from the rest of the codebase, they are a good
place to start for aspiring maintainers and contributors. Get in touch if you want to help maintain them!
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