Add Alpine Linux configuration

Signed-off-by: Jiayi Hu <jiayi.ghu@gmail.com>

roles/raspberrypi/handlers/main.yml

@@ -1,3 +1,7 @@
 ---
 - name: reboot
   reboot:
+
+- name: lbu
+  debug:
+    msg: If you are diskless on Alpine you should commit changes with 'lbu -u' now and reboot.

roles/raspberrypi/tasks/prereq/Alpine.yml

@@ -0,0 +1,29 @@
+---
+- name: Add cgroup mount point
+  lineinfile:
+    path: /etc/fstab
+    line: cgroup /sys/fs/cgroup cgroup defaults 0 0
+
+- name: Define cgroup mount points
+  copy:
+    content: |
+      mount {
+        cpuacct = /cgroup/cpuacct;
+        memory = /cgroup/memory;
+        devices = /cgroup/devices;
+        freezer = /cgroup/freezer;
+        net_cls = /cgroup/net_cls;
+        blkio = /cgroup/blkio;
+        cpuset = /cgroup/cpuset;
+        cpu = /cgroup/cpu;
+      }
+    dest: /etc/cgconfig.conf
+    mode: 0644
+
+- name: Enable cgroup via boot commandline if not already enabled
+  lineinfile:
+    path: /media/mmcblk0p1/cmdline.txt
+    backrefs: yes
+    regexp: '^((?!.*\bcgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory\b).*)$'
+    line: '\1 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory'
+  notify: lbu