Cannot set interface to "::" to enable IPv6

[rhertzog]

https://docs.saltstack.com/en/latest/ref/configuration/master.html explains that to enable IPv6 you must set the interface option to '::'. So I have put this in pillar:

salt:
  master:
    ipv6: True
    interface: '::'

But if you apply the salt.master state with this value it will generate an invalid configuration file as it will put the string without the quotes in the generated file:

$ grep ^interface /etc/salt/master.d/f_defaults.conf
interface: ::

And this breaks the salt master... somehow we must enhance the code which embeds strings in the configuration file to add the required quotes.

The code for the minion does use the "json" output filter which avoids this, we should do the same with the master configuration file.

[rhertzog]

Something like this:

diff --git a/salt/files/master.d/f_defaults.conf b/salt/files/master.d/f_defaults.conf
index 29b5f8a..9b0d87c 100644
--- a/salt/files/master.d/f_defaults.conf
+++ b/salt/files/master.d/f_defaults.conf
@@ -5,11 +5,11 @@
 {% set cfg_master = cfg_salt.get('master', {}) -%}
 {%- macro get_config(configname, default_value) -%}
 {%- if configname in cfg_master -%}
-{{ configname }}: {{ cfg_master[configname] }}
+{{ configname }}: {{ cfg_master[configname]|json }}
 {%- elif configname in cfg_salt and configname not in reserved_keys -%}
-{{ configname }}: {{ cfg_salt[configname] }}
+{{ configname }}: {{ cfg_salt[configname]|json }}
 {%- else -%}
-#{{ configname }}: {{ default_value }}
+#{{ configname }}: {{ default_value|json }}
 {%- endif -%}
 {%- endmacro -%}
 {%- from 'salt/formulas.jinja' import file_roots, formulas with context -%}