Adjust file descriptor limit when systemd is used

Change-Id: I29629ba3c78a55ebd63e4f9710ba71b85c488279
Related-Bug: #1623164

handlers/main.yml

@@ -13,6 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+- name: Reload the systemd daemon
+  command: "systemctl daemon-reload"
+  when:
+    - pid1_name == "systemd"
+
 - name: Restart memcached
   service:
     name: "memcached"

tasks/main.yml

@@ -24,6 +24,18 @@
   tags:
     - always
 
+- name: Check init system
+  command: cat /proc/1/comm
+  register: _pid1_name
+  tags:
+    - always
+
+- name: Set the name of pid1
+  set_fact:
+    pid1_name: "{{ _pid1_name.stdout }}"
+  tags:
+    - always
+
 - include: memcached_install.yml
   tags:
     - memcached-install

tasks/memcached_config.yml

@@ -40,7 +40,17 @@
     mode: "0644"
   notify: Restart memcached
 
-- name: Apply resource limits
+- name: Create memcached systemd service config dir
+  file:
+    path: "/etc/systemd/system/memcached.service.d"
+    state: "directory"
+    group: "root"
+    owner: "root"
+    mode: "0755"
+  when:
+    - pid1_name == "systemd"
+
+- name: Apply resource limits (upstart)
   template:
     src: "memcached.debian.j2"
     dest: "/etc/default/memcached"
@@ -49,9 +59,24 @@
     mode: "0644"
   when:
     - ansible_pkg_mgr == 'apt'
+    - pid1_name != "systemd"
     - memcached_connections > 1024
   notify: Restart memcached
 
+- name: Apply resource limits (systemd)
+  template:
+    src: "limits.conf.j2"
+    dest: "/etc/systemd/system/memcached.service.d/limits.conf"
+    owner: "root"
+    group: "root"
+    mode: "0644"
+  when:
+    - pid1_name == "systemd"
+    - memcached_connections > 1024
+  notify:
+    - Reload the systemd daemon
+    - Restart memcached
+
 - name: Configure soft file limits
   lineinfile:
     dest: "/etc/security/limits.conf"

templates/limits.conf.j2

@@ -0,0 +1,4 @@
+# {{ ansible_managed }}
+
+[Service]
+LimitNOFILE={{ memcached_connections }}