fix: make necessary modifications to get working on `salt-ssh`

* Similar situation to https://github.com/saltstack-formulas/logrotate-formula/pull/53
  - https://freenode.logbot.info/saltstack-formulas/20200507#c3819526-c3819581
  - https://freenode.logbot.info/saltstack-formulas/20200508#c3826763-c3826995
* Send template values by `context`

postfix/config.sls

@@ -21,6 +21,8 @@ include:
     - watch_in:
       - service: postfix
     - template: jinja
+    - context:
+        postfix: {{ postfix|tojson }}
 
 {% if 'vmail' in pillar.get('postfix', '') %}
 {{ postfix.config_path }}/virtual_alias_maps.cf:
@@ -61,6 +63,7 @@ include:
 {% endif %}
 
 {% if salt['pillar.get']('postfix:manage_master_config', True) %}
+{% import_yaml "postfix/services.yaml" as postfix_master_services %}
 {{ postfix.config_path }}/master.cf:
   file.managed:
     - source: salt://postfix/files/master.cf
@@ -72,6 +75,9 @@ include:
     - watch_in:
       - service: postfix
     - template: jinja
+    - context:
+        postfix: {{ postfix|tojson }}
+        postfix_master_services: {{ postfix_master_services|tojson }}
 {% endif %}
 
 {% if 'transport' in pillar.get('postfix', '') %}

postfix/files/main.cf

@@ -1,4 +1,3 @@
-{%- from "postfix/map.jinja" import postfix with context -%}
 {%- set config = salt['pillar.get']('postfix:config', {}) -%}
 
 {#- " | list": Python3.6 retuns dict_keys here, which needs to be converted into a list here. -#}

postfix/files/master.cf

@@ -1,7 +1,4 @@
-{%- from "postfix/map.jinja" import postfix with context -%}
 {%- set master_config = salt['pillar.get']('postfix:master_config', {}) -%}
-{% import_yaml "postfix/services.yaml" as postfix_master_services %}
-
 {#-
  # Handle the case that the pillar data does not provide any service
  # configuration but submission parameters are provided in the pillar.