diff --git a/roles/download/defaults/main.yml b/roles/download/defaults/main.yml
index 4437861ae..d6c772a6d 100644
--- a/roles/download/defaults/main.yml
+++ b/roles/download/defaults/main.yml
@@ -61,6 +61,13 @@ kubeadm_checksum: 6b17720a65b8ff46efe92a5544f149c39a221910d89939838d75581d4e6924
 vault_binary_checksum: 3c4d70ba71619a43229e65c67830e30e050eab7a81ac6b28325ff707e5914188
 
 # Containers
+# In some cases, we need a way to set --registry-mirror or --insecure-registry for docker,
+# it helps a lot for local private development or bare metal environment.
+# So you need define --registry-mirror or --insecure-registry, and modify the following url address.
+# example:
+# You need to deploy kubernetes cluster on local private development.
+# Also provide the address of your own private registry.
+# And use --insecure-registry options for docker
 etcd_image_repo: "quay.io/coreos/etcd"
 etcd_image_tag: "{{ etcd_version }}{%- if image_arch != 'amd64' -%}-{{ image_arch }}{%- endif -%}"
 flannel_image_repo: "quay.io/coreos/flannel"
diff --git a/roles/kubespray-defaults/defaults/main.yaml b/roles/kubespray-defaults/defaults/main.yaml
index b6514aad7..6288811eb 100644
--- a/roles/kubespray-defaults/defaults/main.yaml
+++ b/roles/kubespray-defaults/defaults/main.yaml
@@ -144,14 +144,14 @@ container_manager: docker
 
 ## Uncomment this if you want to force overlay/overlay2 as docker storage driver
 ## Please note that overlay2 is only supported on newer kernels
-#docker_storage_options: -s overlay2
+# docker_storage_options: -s overlay2
 
 ## Enable docker_container_storage_setup, it will configure devicemapper driver on Centos7 or RedHat7.
 docker_container_storage_setup: false
 
 ## It must be define a disk path for docker_container_storage_setup_devs.
 ## Otherwise docker-storage-setup will be executed incorrectly.
-#docker_container_storage_setup_devs: /dev/vdb
+# docker_container_storage_setup_devs: /dev/vdb
 
 ## Uncomment this if you have more than 3 nameservers, then we'll only use the first 3.
 docker_dns_servers_strict: false
@@ -166,18 +166,15 @@ docker_iptables_enabled: "false"
 # Rotate container stderr/stdout logs at 50m and keep last 5
 docker_log_opts: "--log-opt max-size=50m --log-opt max-file=5"
 
-# define docker bin_dir
-docker_bin_dir: "/usr/bin"
-
 ## An obvious use case is allowing insecure-registry access to self hosted registries.
 ## Can be ipddress and domain_name.
 ## example define 172.19.16.11 or mirror.registry.io
-#insecure_registries:
+# insecure_registries:
 #   - mirror.registry.io
 #   - 172.19.16.11
 
 ## Add other registry,example China registry mirror.
-#registry_mirrors:
+# registry_mirrors:
 #   - https://registry.docker-cn.com
 #   - https://mirror.aliyuncs.com
 
@@ -186,7 +183,7 @@ docker_bin_dir: "/usr/bin"
 ## 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:
+# docker_mount_flags:
 
 ## A string of extra options to pass to the docker daemon.
 ## This string should be exactly as you wish it to appear.