Simplify input type Helm #977

docs/pages/input_types/helm.md

@@ -1,6 +1,7 @@
 # :kapitan-logo: **Input Type | Helm**
 
-This is a Python binding to `helm template` command for users with helm charts. This does not require the helm executable, and the templates are rendered without the Tiller server.
+This is a Python binding to `helm template` command for users with helm charts. This requires the `helm` binary to be installed locally.
+If you're using the kapitan docker image, then the `helm` binary is already instealled inside the image.
 
 Unlike other input types, Helm input types support the following additional parameters under `kapitan.compile`:
 
@@ -25,11 +26,29 @@ parameters:
         …
 ```
 
+Alternatively, instead of using a local `chart_path`, you can omit the `input_path` and specify the URL and chart name directly
+
+```yaml
+parameters:
+  kapitan:
+    compile:
+    - output_path: <output_path>
+      input_type: helm
+      helm_params:
+        repo: https://charts.jetstack.io
+        chart_name: cert-manager
+        version: 1.1.0
+        …
+```
+
 `helm_values` is an object containing values specified that will override the default values in the input chart. This has exactly the same effect as specifying `--values custom_values.yml` for `helm template` command where `custom_values.yml` structure mirrors that of `helm_values`.
 
 `helm_values_files` is an array containing the paths to [helm values files](https://helm.sh/docs/chart_template_guide/values_files/) used as input for the chart. This has exactly the same effect as specifying `--file my_custom_values.yml` for the `helm template` command where `my_custom_values.yml` is a helm values file.
+
 If the same keys exist in `helm_values` and in multiple specified `helm_values_files`, the last indexed file in the `helm_values_files` will take precedence followed by the preceding `helm_values_files` and at the bottom the `helm_values` defined in teh compile block.
+
 There is an example in the tests. The `monitoring-dev`(kapitan/tests/test_resources/inventory/targets/monitoring-dev.yml) and `monitoring-prd`(kapitan/tests/test_resources/inventory/targets/monitoring-prd.yml) targets  both use the `monitoring`(tests/test_resources/inventory/classes/component/monitoring.yml) component.
+
 This component has helm chart input and takes a `common.yml` helm_values file which is "shared" by any target that uses the component and it also takes a dynamically defined file based on a kapitan variable defined in the target.
 
 `helm_path` can be use to provide the helm binary name or path.
@@ -55,7 +74,7 @@ Special flags:
 
 See the [helm doc](https://helm.sh/docs/helm/helm_template/) for further detail.
 
-#### Example
+## Example
 
 Let's use [nginx-ingress](https://github.com/helm/charts/tree/master/stable/nginx-ingress) helm chart as the input. Using [kapitan dependency manager](/external_dependencies.md), this chart can be fetched via a URL as listed in <https://helm.nginx.com/stable/index.yaml>.
 
@@ -107,18 +126,7 @@ $ grep "my-controller" compiled/nginx-from-chart/nginx-ingress/templates/control
         app: my-controller
 ```
 
-#### Building the binding from source
-
-Run
-
-```shell
-cd kapitan/inputs/helm
-./build.sh
-```
-
-This requires Go 1.14.
-
-#### Helm subcharts
+## Helm subcharts
 
 There is an [external dependency manager](/external_dependencies.md) of type `helm` which enables you to specify helm
 charts to download, including subcharts.

kapitan/inputs/base.py

@@ -40,7 +40,7 @@ def compile_obj(self, comp_obj, ext_vars, **kwargs):
 
         # expand any globbed paths, taking into account provided search paths
         input_paths = []
-        for input_path in comp_obj["input_paths"]:
+        for input_path in comp_obj.get("input_paths", []):
             globbed_paths = [glob.glob(os.path.join(path, input_path)) for path in self.search_paths]
             inputs = list(itertools.chain.from_iterable(globbed_paths))
             # remove duplicate inputs
@@ -53,6 +53,11 @@ def compile_obj(self, comp_obj, ext_vars, **kwargs):
                 )
             input_paths.extend(inputs)
 
+        # Enable helm input type to compile without input_paths
+        # This is when we use helm CLI to download the chart
+        if input_type == "helm" and "input_paths" not in comp_obj:
+            self.compile_input_path("", comp_obj, ext_vars, **kwargs)
+
         for input_path in input_paths:
             self.compile_input_path(input_path, comp_obj, ext_vars, **kwargs)
 

kapitan/inputs/helm.py

@@ -144,6 +144,7 @@ def render_chart(
     args = ["template"]
 
     name = helm_params.pop("name", None)
+    chart_name = helm_params.pop("chart_name", None)
     output_file = helm_params.pop("output_file", None)
 
     if helm_flags is None:
@@ -208,9 +209,15 @@ def render_chart(
     if "name_template" not in helm_flags:
         args.append(name or "--generate-name")
 
-    # uses absolute path to make sure helm interprets it as a
-    # local dir and not a chart_name that it should download.
-    args.append(chart_dir)
+    # if chart_name is specified then the last argument to helm_cli is the
+    # name of the chart we want to use. Otherwise it's the chart_dir that
+    # was previously downloaded as an external dependency
+    if chart_name:
+        args.append(chart_name)
+    else:
+        # uses absolute path to make sure helm interprets it as a
+        # local dir and not a chart_name that it should download.
+        args.append(chart_dir)
 
     # If output_path is '-', output is a string with rendered chart
     if output_path == "-":

kapitan/targets.py

@@ -602,7 +602,7 @@ def valid_target_obj(target_obj, require_compile=True):
                         "suffix_remove": {"type": "boolean"},
                         "suffix_stripped": {"type": "string"},
                     },
-                    "required": ["input_type", "input_paths", "output_path"],
+                    "required": ["input_type", "output_path"],
                     "minItems": 1,
                     "oneOf": [
                         {

tests/test_helm_input.py

@@ -49,19 +49,13 @@ def test_compile_chart(self):
         temp = tempfile.mkdtemp()
         sys.argv = ["kapitan", "compile", "--output-path", temp, "-t", "acs-engine-autoscaler"]
         main()
+        base_path = os.path.join(temp, "compiled", "acs-engine-autoscaler")
         self.assertTrue(
-            os.path.isfile(
-                os.path.join(
-                    temp,
-                    "compiled",
-                    "acs-engine-autoscaler",
-                    "acs-engine-autoscaler",
-                    "templates",
-                    "secrets.yaml",
-                )
-            )
+            os.path.isfile(os.path.join(base_path, "acs-engine-autoscaler", "templates", "secrets.yaml"))
         )
 
+        self.assertTrue(os.path.isfile(os.path.join(base_path, "expanded-cert-manager-chart.yaml")))
+
     def test_compile_subcharts(self):
         temp = tempfile.mkdtemp()
         sys.argv = ["kapitan", "compile", "--output-path", temp, "-t", "istio"]

tests/test_resources/inventory/targets/acs-engine-autoscaler.yml

@@ -8,3 +8,11 @@ parameters:
         input_type: helm
         input_paths:
           - charts/acs-engine-autoscaler
+
+      - output_path: .
+        input_type: helm
+        helm_params:
+          repo: https://charts.jetstack.io
+          chart_name: cert-manager
+          version: 1.1.0
+          output_file: expanded-cert-manager-chart.yaml