playbook_sysupgrade: make idempotent

only issue a sysupgrade if the desired garet version and profile
specified in the inventory does not match the firmware running on the
device.

Because we do not put the firmware files into this git, simply
clone the garet repo, checkout the desired commit, build the needed
profile and then put the firmware file into
  firmware/garet_${profile}-${version}.bin

playbook_sysupgrade.yml

@@ -1,19 +1,30 @@
 ---
 - name: upgrade firmware on openwrt device(s)
-  gather_facts: no
   hosts: accesspoints
+  vars:
+    running_garet_profile: "{{ ansible_local['garet']['profile'] | default() }}"
+    running_garet_release: "{{ ansible_local['garet']['release'] | default() }}"
+    firmware_file: "firmware/garet_{{ garet_profile }}-{{ garet_release }}.bin"
+  gather_facts: no
   tasks:
-    - name: upload new firmware
-      copy:
-        src: "{{ firmware_file }}"
-        dest: "/tmp/{{ firmware_file | basename }}"
+    - name: gather firmware version
+      setup:
+        filter: ansible_local
 
-    - name: issue sysupgrade command
-      command:
-        cmd: "sysupgrade /tmp/{{ firmware_file | basename }}"
-      ignore_errors: yes
+    - name: handle update
+      block:
+        - name: upload new firmware
+          copy:
+            src: "{{ firmware_file }}"
+            dest: "/tmp/{{ firmware_file | basename }}"
 
-    - name: wait till device is back online
-      wait_for_connection:
-        delay: 10
-        timeout: 600
+        - name: issue sysupgrade command
+          shell:
+            cmd: "sysupgrade /tmp/{{ firmware_file | basename }} && exit 0"
+          ignore_unreachable: yes
+
+        - name: wait till device is back online
+          wait_for_connection:
+            delay: 10
+            timeout: 600
+      when: garet_profile != running_garet_profile or garet_release != running_garet_release