Add platform template environment support

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/platform/classes.py

@@ -1,5 +1,7 @@
 from __future__ import absolute_import, unicode_literals
 
+import os
+
 import yaml
 try:
     from yaml import CSafeLoader as SafeLoader
@@ -13,12 +15,25 @@ from django.utils.translation import ugettext_lazy as _
 from mayan.apps.task_manager.classes import Worker
 
 
+class Variable(object):
+    def __init__(self, name, default, environment_name):
+        self.name = name
+        self.default = default
+        self.environment_name = environment_name
+
+    def get_value(self):
+        return os.environ.get(self.environment_name, self.default)
+
+
 @python_2_unicode_compatible
 class PlatformTemplate(object):
     _registry = {}
     context = {}
+    context_defaults = {}
     label = None
+    settings = None
     template_name = None
+    variables = None
 
     @classmethod
     def all(cls):
@@ -38,14 +53,42 @@ class PlatformTemplate(object):
     def get_context(self):
         return self.context
 
+    def get_context_defaults(self):
+        return self.context_defaults
+
     def get_label(self):
         return self.label or self.name
 
+    def get_settings_context(self):
+        result = {}
+        for setting in self.settings or ():
+            if setting.value:
+                result[setting.global_name] = setting.value
+
+        return result
+
     def get_template_name(self):
         return self.template_name or 'platform/{}.tmpl'.format(self.name)
 
+    def get_variables_context(self):
+        result = {}
+        for variable in self.variables or ():
+            result[variable.name] = variable.get_value()
+
+        return result
+
     def render(self, context_string=None):
-        context = self.get_context()
+        """
+        context_string allows the management command to pass context to this
+        method as a JSON string
+        """
+        context = {}
+
+        context.update(self.get_context_defaults())
+        context.update(self.get_settings_context())
+        context.update(self.get_variables_context())
+        # get_context goes last to server as the override
+        context.update(self.get_context())
 
         if context_string:
             context.update(
@@ -59,23 +102,61 @@ class PlatformTemplate(object):
         )
 
 
+from mayan.apps.common.settings import (
+    setting_celery_broker_url, setting_celery_result_backend
+)
+
 class PlatformTemplateSupervisord(PlatformTemplate):
+    context_defaults = {
+        'BROKER_URL': 'redis://127.0.0.1:6379/0',
+        'CELERY_RESULT_BACKEND': 'redis://127.0.0.1:6379/0',
+    }
     label = _('Template for Supervisord.')
     name = 'supervisord'
+    settings = (
+        setting_celery_broker_url, setting_celery_result_backend
+    )
+    variables = (
+        Variable(
+            name='GUNICORN_WORKERS', default=2,
+            environment_name='MAYAN_GUNICORN_WORKERS'
+        ),
+        Variable(
+            name='DATABASE_CONN_MAX_AGE', default=60,
+            environment_name='MAYAN_DATABASE_CONN_MAX_AGE'
+        ),
+        Variable(
+            name='DATABASE_ENGINE', default='django.db.backends.postgresql',
+            environment_name='MAYAN_DATABASE_ENGINE'
+        ),
+        Variable(
+            name='DATABASE_HOST', default='127.0.0.1',
+            environment_name='MAYAN_DATABASE_HOST'
+        ),
+        Variable(
+            name='DATABASE_NAME', default='mayan',
+            environment_name='MAYAN_DATABASE_NAME'
+        ),
+        Variable(
+            name='DATABASE_PASSWORD', default='mayanuserpass',
+            environment_name='MAYAN_DATABASE_PASSWORD'
+        ),
+        Variable(
+            name='DATABASE_USER', default='mayan',
+            environment_name='MAYAN_DATABASE_USER'
+        ),
+        Variable(
+            name='INSTALLATION_PATH', default='/opt/mayan-edms',
+            environment_name='MAYAN_INSTALLATION_PATH'
+        ),
+        Variable(
+            name='MEDIA_ROOT', default='/opt/mayan-edms/media',
+            environment_name='MAYAN_MEDIA_ROOT'
+        ),
+    )
 
     def get_context(self):
         return {
-            'gunicorn_workers': 2,
-            'result_backend': 'redis://127.0.0.1:6379/0',
-            'broker_url': 'redis://127.0.0.1:6379/0',
-            'database_conn_max_age': 60,
-            'database_engine': 'django.db.backends.postgresql',
-            'database_host': '127.0.0.1',
-            'database_name': 'mayan',
-            'database_password': 'mayanuserpass',
-            'database_user': 'mayan',
-            'installation_path': '/opt/mayan-edms',
-            'media_root': '/opt/mayan-edms/media',
             'workers': Worker.all()
         }