helm: add support for the K8S_ envvars (#319)

Add support for:

- K8S_AUTH_HOST
- K8S_AUTH_API_KEY
- K8S_AUTH_VERIFY_SSL
- K8S_AUTH_SSL_CA_CERT

This commit also refactor the way we pass K8S related configuration to `helm`:

All the calls are now done in a new module_utils module (`helm.py`).
The handling of the `kube_*` variables has also been moved in this new
module.

We need https://github.com/helm/helm/pull/8622 to be able to ignore the
certificate validation. As a workaround, the generate a temporary
kubeconfig configuration file.

Closes: #279

molecule/default/roles/helm/tasks/run_test.yml

@@ -12,6 +12,9 @@
 - name: "Install {{ helm_version }}"
   include_tasks: install.yml
 
+- name: "Ensure we honor the environment variables"
+  include_tasks: test_read_envvars.yml
+
 - name: tests_repository
   include_tasks: tests_repository.yml
 

molecule/default/roles/helm/tasks/test_read_envvars.yml

@@ -0,0 +1,10 @@
+- name: Pass a bogus server through the K8S_AUTH_HOST environment variable and ensure helm fails as expected
+  helm:
+    binary_path: "{{ helm_binary }}"
+    state: absent
+    name: does-not-exist
+    namespace: "{{ helm_namespace }}"
+  environment:
+    K8S_AUTH_HOST: somewhere
+  register: _helm_result
+  failed_when: '"http://somewhere/version" not in _helm_result.stderr'