Merge pull request #7 from neuroforgede/packaging

Add support for templating of string variables via env vars via {{ nothelm.env.VARIABLE_NAME }}

example/project/templates/sample-stack.yml.j2

@@ -6,6 +6,8 @@ services:
 {% raw %}
     hostname: "hello-{{ .Task.Slot }}"
 {% endraw %}
+    environment:
+      - "SOME_HOME={{ home_dir }}"
     deploy:
       mode: replicated
       replicas: {{ replica_count }}

example/project/values.yaml.j2

@@ -0,0 +1,4 @@
+# no default variables here
+replica_count: 2
+outside_port: 8899
+home_dir: "{{ nothelm.env.HOME }}/hi"

nothelm/lib/template.py

@@ -7,6 +7,39 @@
 import subprocess
 from functools import reduce
 
+def interpolate_env_vars_recursively(values: Dict[str, Any]) -> Dict[str, Any]:
+    def interpolate(value: Any) -> Any:
+        if isinstance(value, dict):
+            return interpolate_dict(value)
+        elif isinstance(value, list):
+            return interpolate_list(value)
+        elif isinstance(value, str):
+            return interpolate_string(value)
+        else:
+            return value
+
+    def interpolate_dict(d: Dict[str, Any]) -> Dict[str, Any]:
+        return {key: interpolate(value) for key, value in d.items()}
+
+    def interpolate_list(l: List[Any]) -> List[Any]:
+        return [interpolate(value) for value in l]
+
+    # expand environment variables, they are available in "jinja" format {{ nothelm.env.VARIABLE_NAME }}
+    def interpolate_jinja(s: str) -> str:
+        env = Environment()
+        template = env.from_string(s)
+        return template.render(nothelm={"env": os.environ})
+
+    def interpolate_string(s: str) -> str:
+        # check if we need to interpolate the string
+        if "{{" in s:
+            return interpolate_jinja(s)
+
+        return os.path.expandvars(s)
+
+    return interpolate_dict(values)
+
+
 def load_values(path: str) -> Dict[str, Any]:
     with open(path, "r") as stream:
         variables = yaml.safe_load(stream)
@@ -17,6 +50,9 @@ def load_values(path: str) -> Dict[str, Any]:
         if not isinstance(variables, dict):
             raise ValueError(f"file at {path} did not contain a YAML dictionary at top level")
 
+        if path.endswith('.j2') or path.endswith('.jinja2'):
+            variables = interpolate_env_vars_recursively(variables)
+
         return variables
 
 
@@ -45,6 +81,8 @@ def template_project(
 
     if os.path.exists(f'{project_dir}/values.yaml'):
         default_values = load_values(f'{project_dir}/values.yaml')
+    elif os.path.exists(f'{project_dir}/values.yaml.j2'):
+        default_values = load_values(f'{project_dir}/values.yaml.j2')
     else:
         default_values = dict()
 

setup.py

@@ -14,7 +14,7 @@ def cli_test_suite():
 setuptools.setup(
     name="nothelm.py",
     scripts=["bin/nothelm"],
-    version="0.2.1",
+    version="0.2.2",
     author="NeuroForge GmbH & Co. KG",
     author_email="[email protected]",
     description="nothelm.py",