Systemd units, limits, and bin path fixes

* Add restart for weave service unit
* Reuse docker_bin_dir everythere
* Limit systemd managed docker containers by CPU/RAM. Do not configure native
  systemd limits due to the lack of consensus in the kernel community
  requires out-of-tree kernel patches.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

roles/network_plugin/flannel/defaults/main.yml

@@ -10,3 +10,9 @@ flannel_public_ip: "{{ access_ip|default(ip|default(ansible_default_ipv4.address
 # You can choose what type of flannel backend to use
 # please refer to flannel's docs : https://github.com/coreos/flannel/blob/master/README.md
 flannel_backend_type: "vxlan"
+
+# Limits for apps
+flannel_memory_limit: 500M
+flannel_cpu_limit: 300m
+flannel_memory_requests: 256M
+flannel_cpu_requests: 150m

roles/network_plugin/flannel/handlers/main.yml

@@ -32,7 +32,7 @@
   pause: seconds=10 prompt="Waiting for docker restart"
 
 - name: Flannel | wait for docker
-  command: /usr/bin/docker images
+  command: "{{ docker_bin_dir }}/docker images"
   register: docker_ready
   retries: 10
   delay: 5

roles/network_plugin/flannel/templates/flannel-pod.yml

@@ -19,6 +19,13 @@
       - name: "flannel-container"
         image: "{{ flannel_image_repo }}:{{ flannel_image_tag }}"
         imagePullPolicy: {{ k8s_image_pull_policy }}
+        resources:
+          limits:
+            cpu: {{ flannel_cpu_limit }}
+            memory: {{ flannel_memory_limit }}
+          requests:
+            cpu: {{ flannel_cpu_requests }}
+            memory: {{ flannel_memory_requests }}
         command:
           - "/bin/sh"
           - "-c"
@@ -26,9 +33,6 @@
         ports:
           - hostPort: 10253
             containerPort: 10253
-        resources:
-          limits:
-            cpu: "100m"
         volumeMounts:
           - name: "subnetenv"
             mountPath: "/run/flannel"