Add to_yaml variable filter (#116)

README.md

@@ -276,6 +276,7 @@ Templates in k8s-handle use jinja2 syntax and support all standard filters + som
 * `{{ my_var | b64encode }}` - encode value of my_var to base64
 * `{{ my_var | b64decode }}` - decode value of my_var from base64
 * `{{ my_var | hash_sha256 }}` - encode value of my_var to sha256sum
+* `{{ my_var | to_yaml(flow_style=True, width=99999) }}` - Tries to render yaml representation of given variable(flow_style=True - render in one line, False multiline. width - max line width for rendered yaml lines) 
 > Warning: You can use filters only for templates and can't for config.yaml
 ### Functions
 * `{{ include_file('my_file.txt') }}` - include my_file.txt to resulting resource w/o parsing it, useful for include configs to configmap.

k8s_handle/templating.py

@@ -59,6 +59,10 @@ def hash_sha256(string):
     return res.hexdigest()
 
 
+def to_yaml(data, flow_style=True, width=99999):
+    return yaml.safe_dump(data, default_flow_style=flow_style, width=width)
+
+
 def get_env(templates_dir):
     # https://stackoverflow.com/questions/9767585/insert-static-files-literally-into-jinja-templates-without-parsing-them
     def include_file(path):
@@ -76,6 +80,7 @@ def include_file(path):
     env.filters['b64decode'] = b64decode
     env.filters['b64encode'] = b64encode
     env.filters['hash_sha256'] = hash_sha256
+    env.filters['to_yaml'] = to_yaml
     env.globals['include_file'] = include_file
 
     log.debug('Available templates in path {}: {}'.format(templates_dir, env.list_templates()))

tests/fixtures/config.yaml

@@ -71,6 +71,23 @@ templates_regex_invalid:
     - template: '['
     - template: template1.yaml.j2
 
+test_filters:
+  to_base64: hello world
+  from_base64: azhzLWhhbmRsZQ==
+  to_sha256: k8s-hanle
+  affinity:
+    - key: "dedicated"
+      operator: "Equal"
+      value: "monitoring"
+      effect: "NoSchedule"
+    - key: "dedicated"
+      operator: "Equal"
+      value:
+        hello: world
+      effect: "NoSchedule"
+  templates:
+    - template: filters.yaml.j2
+
 section_with_kubectl:
   dirs:
     - dst: /tmp/test_directory1/

tests/templates_tests/filters.yaml.j2

@@ -0,0 +1,4 @@
+b64encode: {{ to_base64 | b64encode }}
+b64decode: {{ from_base64 | b64decode }}
+sha256: {{ to_sha256 | hash_sha256 }}
+affinity: {{ affinity | to_yaml() }}

tests/test_templating.py

@@ -1,4 +1,5 @@
 import os
+import yaml
 import shutil
 import unittest
 from k8s_handle import settings
@@ -163,3 +164,19 @@ def test_templates_regex_parse_failed(self):
         with self.assertRaises(TemplateRenderingError) as context:
             r.generate_by_context(c)
         self.assertTrue('Processing [: template [ hasn\'t been found' in str(context.exception))
+
+    def test_filters(self):
+        r = templating.Renderer(os.path.join(os.path.dirname(__file__), 'templates_tests'))
+        context = config.load_context_section('test_filters')
+        r.generate_by_context(context)
+        result = '{}/filters.yaml'.format(settings.TEMP_DIR)
+        with open(result, 'r') as f:
+            actual = yaml.safe_load(f)
+        self.assertEqual('aGVsbG8gd29ybGQ=', actual.get('b64encode'))
+        self.assertEqual('k8s-handle', actual.get('b64decode'))
+        self.assertEqual('8fae6dd899aace000fd494fd6d795e26e2c85bf8e59d4262ef56b03dc91e924c', actual.get('sha256'))
+        affinity = [
+            {'effect': 'NoSchedule', 'key': 'dedicated', 'operator': 'Equal', 'value': 'monitoring'},
+            {'effect': 'NoSchedule', 'key': 'dedicated', 'operator': 'Equal', 'value': {'hello': 'world'}}
+        ]
+        self.assertEqual(affinity, actual.get('affinity'))