Merge ~hloeung/ubuntu-mirror-charm:master into ubuntu-mirror-charm:master

[Haw Loeung]

Ensure Apache HTTP server started after all interfaces are brought up - LP:1899852

See https://pastebin.canonical.com/p/thzPCcv88P/

Testing:

| ubuntu@juju-87625f-hloeung-66:~$ sudo sysctl net.ipv4.ip_nonlocal_bind=0
| net.ipv4.ip_nonlocal_bind = 0
| ubuntu@juju-87625f-hloeung-66:~$ nc -lv -s 10.10.10.10 -p 35000
| nc: Cannot assign requested address

| ubuntu@juju-87625f-hloeung-66:~$ sudo sysctl net.ipv4.ip_nonlocal_bind=1
| net.ipv4.ip_nonlocal_bind = 1
| ubuntu@juju-87625f-hloeung-66:~$ nc -lv -s 10.10.10.10 -p 35000
| Listening on [10.10.10.10] (family 0, port 35000)
| ^C

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

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

[Colin Misare (cmisare)]

LGTM

review: Approve

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

Change successfully merged at revision c50a97a4cc2ffc6349ee03111659039f68f56767

diff --git a/hooks/hooks.py b/hooks/hooks.py
index 62aa81d..3c1b3b4 100755
--- a/hooks/hooks.py
+++ b/hooks/hooks.py
@@ -1071,6 +1071,11 @@ def configure_sysctl(conf, hostname):
         'kernel.pid_max': 65536,
         # RT#90964: Kill swap on ubuntu-archive servers
         'vm.swappiness': 0,
+        # network-online.target but may not be fully up per upstream bug. Let's use
+        # ip_nonlocal_bind for now.
+        # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=868650
+        'net.ipv4.ip_nonlocal_bind': 1,
+        'net.ipv6.ip_nonlocal_bind': 1,
     }
     sysctl.create(yaml.dump(general_settings), '/etc/sysctl.d/90-ubuntu-mirror.conf')
 
diff --git a/templates/systemd-apache-override.tmpl b/templates/systemd-apache-override.tmpl
index 41bd009..1174c49 100644
--- a/templates/systemd-apache-override.tmpl
+++ b/templates/systemd-apache-override.tmpl
@@ -1,3 +1,8 @@
+[Unit]
+# Work around LP:1899852
+After=network-online.target
+Wants=network-online.target
+
 [Service]
 TasksMax=infinity
 LimitNOFILE=${max_fds}