From d6e799565d3eac26734f4a96ba202804f4d29720 Mon Sep 17 00:00:00 2001
From: Stefan Reimer <stefan@zero-downtime.net>
Date: Thu, 4 Jun 2020 16:32:17 +0100
Subject: [PATCH] New feature: create-docs rendering markdown documentation for
 rendered stacks

---
 CHANGES.md              |  4 ++++
 cloudbender/__init__.py |  2 +-
 cloudbender/cli.py      | 13 ++++++++++++
 cloudbender/jinja.py    | 12 +++++++----
 cloudbender/stack.py    | 47 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index ca5a6fa..6a15928 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.8.3
+- New Feature: `create-docs` command
+  Renders a markdown documentation next to the rendered stack templated by parsing parameters and other relvant metadata
+
 ## 0.8.2
 - Bug fix release to allow empty stack configs again
 
diff --git a/cloudbender/__init__.py b/cloudbender/__init__.py
index 607a825..d9fa39f 100644
--- a/cloudbender/__init__.py
+++ b/cloudbender/__init__.py
@@ -2,7 +2,7 @@ import logging
 
 __author__ = "Stefan Reimer"
 __email__ = "stefan@zero-downtimet.net"
-__version__ = "0.8.2"
+__version__ = "0.8.3"
 
 
 # Set up logging to ``/dev/null`` like a library is supposed to.
diff --git a/cloudbender/cli.py b/cloudbender/cli.py
index b026894..80c67a4 100644
--- a/cloudbender/cli.py
+++ b/cloudbender/cli.py
@@ -94,6 +94,18 @@ def outputs(cb, stack_names, multi, include, values):
         s.get_outputs(include, values)
 
 
+@click.command()
+@click.argument("stack_names", nargs=-1)
+@click.option("--multi", is_flag=True, help="Allow more than one stack to match")
+@click.pass_obj
+def create_docs(cb, stack_names, multi):
+    """ Parses all documentation fragments out of rendered templates creating docs/*.md file """
+
+    stacks = _find_stacks(cb, stack_names, multi)
+    for s in stacks:
+        s.create_docs()
+
+
 @click.command()
 @click.argument("stack_name")
 @click.argument("change_set_name")
@@ -240,6 +252,7 @@ cli.add_command(delete)
 cli.add_command(clean)
 cli.add_command(create_change_set)
 cli.add_command(outputs)
+cli.add_command(create_docs)
 
 if __name__ == '__main__':
     cli(obj={})
diff --git a/cloudbender/jinja.py b/cloudbender/jinja.py
index 14c764e..08721fa 100644
--- a/cloudbender/jinja.py
+++ b/cloudbender/jinja.py
@@ -179,10 +179,14 @@ def JinjaEnv(template_locations=[]):
                               extensions=['jinja2.ext.loopcontrols', 'jinja2.ext.do'])
 #                              undefined=SilentUndefined,
 
-    jinja_loaders = []
-    for _dir in template_locations:
-        jinja_loaders.append(jinja2.FileSystemLoader(str(_dir)))
-    jenv.loader = jinja2.ChoiceLoader(jinja_loaders)
+    if template_locations:
+        jinja_loaders = []
+        for _dir in template_locations:
+            jinja_loaders.append(jinja2.FileSystemLoader(str(_dir)))
+        jenv.loader = jinja2.ChoiceLoader(jinja_loaders)
+
+    else:
+        jenv.loader = jinja2.BaseLoader()
 
     jenv.globals['include_raw'] = include_raw_gz
     jenv.globals['raise'] = raise_helper
diff --git a/cloudbender/stack.py b/cloudbender/stack.py
index b502b44..5861581 100644
--- a/cloudbender/stack.py
+++ b/cloudbender/stack.py
@@ -316,6 +316,53 @@ class Stack(object):
         except ClientError as e:
             raise e
 
+    def create_docs(self):
+        """ Read template, parse documentation fragments, eg. parameter description
+            and create a mardown doc file for the stack
+            same idea as eg. helm-docs for values.yaml
+         """
+
+        self.read_template_file()
+
+        doc_template = """
+{{ name }}
+===
+{{ description }}
+
+{% if dependencies %}
+## Dependencies
+{% for d in dependencies|sort %}
+- {{ d }}
+{% endfor %}
+{% endif %}
+
+{% if dependencies %}
+## Parameters
+| Parameter | Type | Default | Format | Description |
+|-----------|------|---------|--------|-------------|
+{% for p in parameters.keys() %}
+| {{ p }} | {{ parameters[p]['Type'] }} | {{ parameters[p]['Default'] }} | {{ parameters[p]['AllowedValues'] or parameters[p]['AllowedPattern']}} | {{ parameters[p]['Description'] }} |
+{% endfor %}
+{% endif %}
+"""
+
+        jenv = JinjaEnv()
+        template = jenv.from_string(doc_template)
+        data = {}
+
+        data['name'] = self.stackname
+        data['description'] = self.cfn_data['Description']
+        data['dependencies'] = self.dependencies
+
+        if 'Parameters' in self.cfn_data:
+            data['parameters'] = self.cfn_data['Parameters']
+
+        doc_file = os.path.join(self.ctx['template_path'], self.rel_path, self.stackname.upper() + ".md")
+
+        with open(doc_file, 'w') as doc_contents:
+            doc_contents.write(template.render(**data))
+            logger.info('Wrote documentation for %s to %s', self.stackname, doc_file)
+
     def resolve_parameters(self):
         """ Renders parameters for the stack based on the source template and the environment configuration """