move flexvolume plugin directory creation to preinstall (#4999)

* move flexvolume plugin directory creation to preinstall

* changes per pr feedback

Author: Jeff Bornemann

inventory/sample/group_vars/k8s-cluster/k8s-cluster.yml

@@ -191,6 +191,9 @@ podsecuritypolicy_enabled: false
 # Acceptable options are 'pods', 'system-reserved', 'kube-reserved' and ''. Default is "".
 # kubelet_enforce_node_allocatable: pods
 
+# An alternative flexvolume plugin directory
+# kubelet_flexvolumes_plugins_dir: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
+
 ## Supplementary addresses that can be added in kubernetes ssl keys.
 ## That can be useful for example to setup a keepalived virtual IP
 # supplementary_addresses_in_ssl_keys: [10.0.0.1, 10.0.0.2, 10.0.0.3]

roles/kubernetes/node/defaults/main.yml

@@ -50,8 +50,6 @@ loadbalancer_apiserver_cpu_requests: 25m
 #   - extensions/v1beta1/daemonsets=true
 #   - extensions/v1beta1/deployments=true
 
-kubelet_flexvolumes_plugins_dir: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
-
 # A port range to reserve for services with NodePort visibility.
 # Inclusive at both ends of the range.
 kube_apiserver_node_port_range: "30000-32767"

roles/kubernetes/node/templates/kubelet.service.j2

@@ -7,7 +7,6 @@ Wants=docker.socket
 [Service]
 User=root
 EnvironmentFile=-{{ kube_config_dir }}/kubelet.env
-ExecStartPre=-/bin/mkdir -p {{ kubelet_flexvolumes_plugins_dir }}
 ExecStart={{ bin_dir }}/kubelet \
 		$KUBE_LOGTOSTDERR \
 		$KUBE_LOG_LEVEL \

roles/kubernetes/preinstall/defaults/main.yml

@@ -25,6 +25,7 @@ kube_cert_group: kube-cert
 kube_config_dir: /etc/kubernetes
 kube_cert_dir: "{{ kube_config_dir }}/ssl"
 kube_cert_compat_dir: /etc/kubernetes/pki
+kubelet_flexvolumes_plugins_dir: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
 
 # Container Linux by CoreOS cloud init config file to define /etc/resolv.conf content
 # for hostnet pods and infra needs

roles/kubernetes/preinstall/tasks/0040-set_facts.yml

@@ -178,3 +178,13 @@
     etcd_deployment_type: host
   when:
     - etcd_kubeadm_enabled
+
+- name: check /usr readonly
+  stat:
+    path: "/usr"
+  register: usr
+
+- name: set alternate flexvolume path
+  set_fact:
+    kubelet_flexvolumes_plugins_dir: /var/lib/kubelet/volumeplugins
+  when: not usr.stat.writeable

roles/kubernetes/preinstall/tasks/0050-create_directories.yml

@@ -22,6 +22,7 @@
     - "{{ kube_cert_dir }}"
     - "{{ kube_manifest_dir }}"
     - "{{ kube_script_dir }}"
+    - "{{ kubelet_flexvolumes_plugins_dir }}"
 
 - name: Check if kubernetes kubeadm compat cert dir exists
   stat: