From cf9e4121f61fe3fbeaa4cd89951d26c6225ce990 Mon Sep 17 00:00:00 2001
From: Radek Zajic <radek.zajic@showmax.com>
Date: Tue, 5 May 2020 13:50:36 +0200
Subject: [PATCH] Debian: avoid misconfigured interfaces on up/down script
 errors

In Debian, if you bring up dual-stack interfaces, the pre/post-up/down
scripts are run on the configuration of each stack. I.e. if you bring up
the IPv4 config on an interface, the ifupdown scripts launch scripts in
the post-up directory. These scripts are common for IPv4 and IPv6 in current
version of puppet-network. At the moment IPv6 is not yet configured, but
IPv6 commands are called - and fail. If an IPv6 command (e.g. `ip -6 route add`)
is the last one in the post-up script, the overall post-up script fails.

When the post-up script fails when bringing up the IPv4 configuration,
ifupdown no longer attempts to bring up the IPv6 configuration on that
interface and leaves the interface misconfigured (IPv4 is configured,
IPv6 is not).

This situation can be avoided by adding the `exit 0` command at the very
end of the script files. It is okay if the IPv6 commands in the common script
fail when only IPv4 is brought up, as ifupdown will re-run them after
IPv6 is brought up.
---
 templates/interface/Debian.erb  | 1 +
 templates/route_down-Debian.erb | 2 ++
 templates/route_up-Debian.erb   | 2 ++
 templates/rule_down-Debian.erb  | 2 ++
 templates/rule_up-Debian.erb    | 2 ++
 5 files changed, 9 insertions(+)

diff --git a/templates/interface/Debian.erb b/templates/interface/Debian.erb
index 6c2b3e3..2aebec2 100644
--- a/templates/interface/Debian.erb
+++ b/templates/interface/Debian.erb
@@ -1,3 +1,4 @@
+# File Managed by Puppet
 # Interface <%= @name %>
 <% if @description and ! @description.empty? -%>
 # <%= @description %>
diff --git a/templates/route_down-Debian.erb b/templates/route_down-Debian.erb
index 7c06013..f4f4301 100644
--- a/templates/route_down-Debian.erb
+++ b/templates/route_down-Debian.erb
@@ -10,3 +10,5 @@ if [ "$IFACE" = "<%= @interface -%>" ] || [ "$IFACE" = "--all" ]; then
   fi
 <%- end -%>
 fi
+# non-zero exit code causes ifupdown to leave the interface partly configured, which may result in connectivity loss
+exit 0
diff --git a/templates/route_up-Debian.erb b/templates/route_up-Debian.erb
index 7dcfbc0..c4733c6 100644
--- a/templates/route_up-Debian.erb
+++ b/templates/route_up-Debian.erb
@@ -10,3 +10,5 @@ if [ "$IFACE" = "<%= @interface -%>" ] || [ "$IFACE" = "--all" ]; then
   fi
 <%- end -%>
 fi
+# non-zero exit code causes ifupdown to leave the interface partly configured, which may result in connectivity loss
+exit 0
diff --git a/templates/rule_down-Debian.erb b/templates/rule_down-Debian.erb
index 20e6b15..26fa6dd 100644
--- a/templates/rule_down-Debian.erb
+++ b/templates/rule_down-Debian.erb
@@ -10,3 +10,5 @@ if [ "$IFACE" = "<%= @interface -%>" ] || [ "$IFACE" = "--all" ]; then
   fi
 <%- end -%>
 fi
+# non-zero exit code causes ifupdown to leave the interface partly configured, which may result in connectivity loss
+exit 0
diff --git a/templates/rule_up-Debian.erb b/templates/rule_up-Debian.erb
index 0ba92be..f1f1626 100644
--- a/templates/rule_up-Debian.erb
+++ b/templates/rule_up-Debian.erb
@@ -10,3 +10,5 @@ if [ "$IFACE" = "<%= @interface -%>" ] || [ "$IFACE" = "--all" ]; then
   fi
 <%- end -%>
 fi
+# non-zero exit code causes ifupdown to leave the interface partly configured, which may result in connectivity loss
+exit 0