kube: add support for --userns=

add support to override the user namespace to use for the pod.

Closes: https://github.com/containers/podman/issues/7504

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/docs/source/markdown/podman-play-kube.1.md b/docs/source/markdown/podman-play-kube.1.md
index 8ed71b734..5c4bdc8c4 100644
--- a/docs/source/markdown/podman-play-kube.1.md
+++ b/docs/source/markdown/podman-play-kube.1.md
@@ -243,6 +243,45 @@ Require HTTPS and verify certificates when contacting registries (default: true)
 then TLS verification will be used. If set to false, then TLS verification will not be used. If not specified,
 TLS verification will be used unless the target registry is listed as an insecure registry in registries.conf.
 
+#### **--userns**=*mode*
+
+Set the user namespace mode for the container. It defaults to the **PODMAN_USERNS** environment variable. An empty value ("") means user namespaces are disabled unless an explicit mapping is set with the **--uidmap** and **--gidmap** options.
+
+Rootless user --userns=Key mappings:
+
+Key       | Host User |  Container User
+----------|---------------|---------------------
+""        |$UID           |0 (Default User account mapped to root user in container.)
+keep-id   |$UID           |$UID (Map user account to same UID within container.)
+auto      |$UID           | nil (Host User UID is not mapped into container.)
+nomap     |$UID           | nil (Host User UID is not mapped into container.)
+
+Valid _mode_ values are:
+
+**auto**[:_OPTIONS,..._]: automatically create a unique user namespace.
+
+The `--userns=auto` flag, requires that the user name `containers` and a range of subordinate user ids that the Podman container is allowed to use be specified in the /etc/subuid and /etc/subgid files.
+
+Example: `containers:2147483647:2147483648`.
+
+Podman allocates unique ranges of UIDs and GIDs from the `containers` subordinate user ids. The size of the ranges is based on the number of UIDs required in the image. The number of UIDs and GIDs can be overridden with the `size` option. The `auto` options currently does not work in rootless mode
+
+  Valid `auto` options:
+
+  - *gidmapping*=_CONTAINER_GID:HOST_GID:SIZE_: to force a GID mapping to be present in the user namespace.
+  - *size*=_SIZE_: to specify an explicit size for the automatic user namespace. e.g. `--userns=auto:size=8192`. If `size` is not specified, `auto` will estimate a size for the user namespace.
+  - *uidmapping*=_CONTAINER_UID:HOST_UID:SIZE_: to force a UID mapping to be present in the user namespace.
+
+**container:**_id_: join the user namespace of the specified container.
+
+**host**: create a new namespace for the container.
+
+**keep-id**: creates a user namespace where the current rootless user's UID:GID are mapped to the same values in the container. This option is ignored for containers created by the root user.
+
+**nomap**: creates a user namespace where the current rootless user's UID:GID are not mapped into the container. This option is ignored for containers created by the root user.
+
+**ns:**_namespace_: run the pod in the given existing user namespace.
+
 ## EXAMPLES
 
 Recreate the pod and containers as described in a file called `demo.yml`