During "join" of new control plane machines, kubeadm would
download shared certificates and keys from the cluster stored
in a Secret. Based on the contents of an entry in the Secret,
it would use helper functions from client-go to either write
it as public key, cert (mode 644) or as a private key (mode 600).
The existing logic is always writing both keys and certs with mode 600.
Allow detecting public readable data properly and writing some files
with mode 644.
First check the data with ParsePrivateKeyPEM(); if this passes
there must be at least one private key and the file should be written
with mode 600 as private. If that fails, validate if the data contains
public keys with ParsePublicKeysPEM() and write the file as public
(mode 644).
As a result of this new logic, and given the current set of managed
kubeadm files, .key files will end up with 600, while .crt and .pub
files will end up with 644.
Add {Init|Join}Configuration.Patches, which is a structure that
contains patch related options. Currently it only has the "Directory"
field which is the same option as the existing --experimental-patches
flag.
The flags --[experimental-]patches value override this value
if both a flag and config is passed during "init" or "join".
The feature of "patches" in kubeadm has been in Alpha for a few
releases. It has not received major bug reports from users.
Deprecate the --experimental-patches flag and add --patches.
Both flags are allowed to be mixed with --config.
If the user has not specified a pull policy we must assume a default of
v1.PullIfNotPresent.
Add some extra verbose output to help users monitor what policy is
used and what images are skipped / pulled.
Use "fallthrough" and case handle "v1.PullAlways".
Update unit test.
In the Alpha stage of the feature in kubeadm to support
a rootless control plane, the allocation and assignment of
UID/GIDs to containers in the static pods will be automated.
This automation will require management of users and groups
in /etc/passwd and /etc/group.
The tools on Linux for user/group management are inconsistent
and non-standardized. It also requires us to include a number of
more dependencies in the DEB/RPMs, while complicating the UX for
non-package manager users.
The format of /etc/passwd and /etc/group is standardized.
Add code for managing (adding and deleting) a set of managed
users and groups in these files.
