Merge ~hloeung/ubuntu-repository-cache:fixes into ubuntu-repository-cache:master

[Haw Loeung]

Fix failure trying to initialise squid caches by calling wrong squid command/binary

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Junien F (axino)]

+1

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision a0599fb7616410e0c3de620f4a69f933d6c40271

diff --git a/lib/ubuntu_repository_cache/squid.py b/lib/ubuntu_repository_cache/squid.py
index e3b15cd..2ddf436 100644
--- a/lib/ubuntu_repository_cache/squid.py
+++ b/lib/ubuntu_repository_cache/squid.py
@@ -32,7 +32,14 @@ def init_caches():
     if not unitdata.kv().get('squid-disk-caches'):
         LOG('No on disk cache directories founds for squid.', hookenv.ERROR)
         return
-    subprocess.check_call(['/usr/sbin/squid3', '-N', '-z', '-f', '/etc/squid-deb-proxy/squid-deb-proxy.conf'])
+
+    release = lsb_release()['DISTRIB_RELEASE']
+    if release < '16.04':  # before xenial
+        squid_cmd = '/usr/sbin/squid3'
+    else:
+        squid_cmd = '/usr/sbin/squid'
+
+    subprocess.check_call([squid_cmd, '-N', '-z', '-f', '/etc/squid-deb-proxy/squid-deb-proxy.conf'])
 
 
 def size_caches(system_total_memory=0):