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/weave/defaults/main.yml

@@ -0,0 +1,4 @@
+---
+# Limits
+weave_memory_limit: 500M
+weave_cpu_limit: 300m

roles/network_plugin/weave/tasks/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: Weave | Copy cni plugins from hyperkube
-  command: "/usr/bin/docker run --rm -v /opt/cni/bin:/cnibindir {{ hyperkube_image_repo }}:{{ hyperkube_image_tag }} /bin/cp -r /opt/cni/bin/. /cnibindir/"
+  command: "{{ docker_bin_dir }}/docker run --rm -v /opt/cni/bin:/cnibindir {{ hyperkube_image_repo }}:{{ hyperkube_image_tag }} /bin/cp -r /opt/cni/bin/. /cnibindir/"
   register: cni_task_result
   until: cni_task_result.rc == 0
   retries: 4

roles/network_plugin/weave/templates/weave.j2

@@ -1,3 +1,4 @@
+WEAVE_DOCKER_ARGS="--memory={{ weave_memory_limit|regex_replace('Mi', 'M') }} --cpu-shares={{ weave_cpu_limit|regex_replace('m', '') }}"
 WEAVE_PEERS="{% for host in groups['k8s-cluster'] %}{{ hostvars[host]['access_ip'] | default(hostvars[host]['ip'] | default(hostvars[host]['ansible_default_ipv4']['address'])) }}{% if not loop.last %} {% endif %}{% endfor %}"
 WEAVEPROXY_ARGS="--rewrite-inspect --without-dns"
 WEAVE_SUBNET="--ipalloc-range {{ kube_pods_subnet }}"

roles/network_plugin/weave/templates/weave.service.j2

@@ -6,12 +6,13 @@ After=docker.service docker.socket
 
 [Service]
 EnvironmentFile=-/etc/weave.env
-ExecStartPre=-/usr/bin/docker rm -f weave
+ExecStartPre=-{{ docker_bin_dir }}/docker rm -f weave
 ExecStartPre={{ bin_dir }}/weave launch-router \
             $WEAVE_SUBNET \
             $WEAVE_PEERS
-ExecStart=/usr/bin/docker attach weave
+ExecStart={{ docker_bin_dir }}/docker attach weave
 ExecStop={{ bin_dir }}/weave stop
+Restart=on-failure
 
 [Install]
 WantedBy=multi-user.target

roles/network_plugin/weave/templates/weaveproxy.service.j2

@@ -7,11 +7,11 @@ After=docker.service docker.socket
 [Service]
 EnvironmentFile=-/etc/weave.%H.env
 EnvironmentFile=-/etc/weave.env
-ExecStartPre=-/usr/bin/docker rm -f weaveproxy
+ExecStartPre=-{{ docker_bin_dir }}/docker rm -f weaveproxy
 ExecStartPre={{ bin_dir }}/weave launch-proxy $WEAVEPROXY_ARGS
-ExecStart=/usr/bin/docker attach weaveproxy
+ExecStart={{ docker_bin_dir }}/docker attach weaveproxy
 Restart=on-failure
-ExecStop=/opt/bin/weave stop-proxy
+ExecStop={{ bin_dir }}/weave stop-proxy
 
 [Install]
 WantedBy=weave-network.target