rc.2 release notes: https://github.com/opencontainers/runc/releases/tag/v1.2.0-rc.2
rc.1 release notes: https://github.com/opencontainers/runc/releases/tag/v1.2.0-rc.1

Breaking changes and deprecations are included below;

Breaking changes:

Several aspects of how mount options work has been adjusted in a way that
could theoretically break users that have very strange mount option strings.
This was necessary to fix glaring issues in how mount options were being
treated. The key changes are:

- Mount options on bind-mounts that clear a mount flag are now always
  applied. Previously, if a user requested a bind-mount with only clearing
  options (such as rw,exec,dev) the options would be ignored and the
  original bind-mount options would be set. Unfortunately this also means
  that container configurations which specified only clearing mount options
  will now actually get what they asked for, which could break existing
  containers (though it seems unlikely that a user who requested a specific
  mount option would consider it "broken" to get the mount options they
  asked foruser who requested a specific mount option would consider it
  "broken" to get the mount options they asked for). This also allows us to
  silently add locked mount flags the user did not explicitly request to be
  cleared in rootless mode, allowing for easier use of bind-mounts for
  rootless containers.
- Container configurations using bind-mounts with superblock mount flags
  (i.e. filesystem-specific mount flags, referred to as "data" in
  mount(2), as opposed to VFS generic mount flags like MS_NODEV) will
  now return an error. This is because superblock mount flags will also
  affect the host mount (as the superblock is shared when bind-mounting),
  which is obviously not acceptable. Previously, these flags were silently
  ignored so this change simply tells users that runc cannot fulfil their
  request rather than just ignoring it.

Deprecated

- runc option --criu is now ignored (with a warning), and the option will
  be removed entirely in a future release. Users who need a non-standard
  criu binary should rely on the standard way of looking up binaries in
  $PATH.
- runc kill option -a is now deprecated. Previously, it had to be specified
  to kill a container (with SIGKILL) which does not have its own private PID
  namespace (so that runc would send SIGKILL to all processes). Now, this is
  done automatically.
- github.com/opencontainers/runc/libcontainer/user is now deprecated, please
  use github.com/moby/sys/user instead. It will be removed in a future
  release.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>