Added docker_mount_flags option (fixes #2624)

inventory/sample/group_vars/k8s-cluster.yml

@@ -148,6 +148,13 @@ docker_daemon_graph: "/var/lib/docker"
 docker_options: "--insecure-registry={{ kube_service_addresses }} --graph={{ docker_daemon_graph }}  {{ docker_log_opts }}"
 docker_bin_dir: "/usr/bin"
 
+## If non-empty will override default system MounFlags value.
+## This option takes a mount propagation flag: shared, slave
+## or private, which control whether mounts in the file system
+## namespace set up for docker will receive or propagate mounts
+## and unmounts. Leave empty for system default
+docker_mount_flags:
+
 # Settings for containerized control plane (etcd/kubelet/secrets)
 etcd_deployment_type: docker
 kubelet_deployment_type: host

roles/docker/templates/docker-options.conf.j2

@@ -1,3 +1,6 @@
 [Service]
 Environment="DOCKER_OPTS={{ docker_options | default('') }} \
 --iptables=false"
+{% if docker_mount_flags is defined and docker_mount_flags != "" %}
+MountFlags={{ docker_mount_flags }}
+{% endif %}

roles/kubespray-defaults/defaults/main.yaml

@@ -146,6 +146,13 @@ docker_log_opts: "--log-opt max-size=50m --log-opt max-file=5"
 ## to self hosted registries like so:
 docker_options: "--insecure-registry={{ kube_service_addresses }} --graph={{ docker_daemon_graph }} {{ docker_log_opts }}"
 
+## If non-empty will override default system MounFlags value.
+## This option takes a mount propagation flag: shared, slave
+## or private, which control whether mounts in the file system
+## namespace set up for docker will receive or propagate mounts
+## and unmounts. Leave empty for system default
+docker_mount_flags:
+
 # Settings for containerized control plane (etcd/kubelet/secrets)
 etcd_deployment_type: docker
 kubelet_deployment_type: docker