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

tests/unit/module_utils/test_helm.py

@@ -0,0 +1,100 @@
+# -*- coding: utf-8 -*-
+# Copyright: (c) 2020, Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+
+__metaclass__ = type
+
+import os.path
+
+import yaml
+
+
+from ansible_collections.community.kubernetes.plugins.module_utils.helm import (
+    run_helm,
+    write_temp_kubeconfig,
+)
+
+
+class MockedModule:
+    def __init__(self):
+
+        self.params = {
+            "api_key": None,
+            "ca_cert": None,
+            "host": None,
+            "kube_context": None,
+            "kubeconfig": None,
+            "release_namespace": None,
+            "validate_certs": None,
+        }
+
+        self.r = {}
+
+    def run_command(self, command, environ_update=None):
+        self.r = {"command": command, "environ_update": environ_update}
+        return 0, "", ""
+
+
+def test_write_temp_kubeconfig_server_only():
+    file_name = write_temp_kubeconfig("ff")
+    try:
+        with open(file_name, "r") as fd:
+            content = yaml.load(fd)
+    finally:
+        os.remove(file_name)
+
+    assert content == {
+        "apiVersion": "v1",
+        "clusters": [{"cluster": {"server": "ff"}, "name": "generated-cluster"}],
+        "contexts": [
+            {"context": {"cluster": "generated-cluster"}, "name": "generated-context"}
+        ],
+        "current-context": "generated-context",
+        "kind": "Config",
+    }
+
+
+def test_write_temp_kubeconfig_server_inscure_certs():
+    file_name = write_temp_kubeconfig("ff", False, "my-certificate")
+    try:
+        with open(file_name, "r") as fd:
+            content = yaml.load(fd)
+    finally:
+        os.remove(file_name)
+
+    assert content["clusters"][0]["cluster"]["insecure-skip-tls-verify"] is True
+    assert (
+        content["clusters"][0]["cluster"]["certificate-authority"] == "my-certificate"
+    )
+
+
+def test_run_helm_naked():
+    module = MockedModule()
+    run_helm(module, "helm foo")
+
+    assert module.r["command"] == "helm foo"
+    assert module.r["environ_update"] == {}
+
+
+def test_run_helm_with_params():
+    module = MockedModule()
+    module.params = {
+        "api_key": "my-api-key",
+        "ca_cert": "my-ca-cert",
+        "host": "some-host",
+        "kube_context": "my-context",
+        "release_namespace": "a-release-namespace",
+        "validate_certs": False,
+    }
+
+    run_helm(module, "helm foo")
+
+    assert module.r["command"] == "helm foo"
+    assert module.r["environ_update"]["HELM_KUBEAPISERVER"] == "some-host"
+    assert module.r["environ_update"]["HELM_KUBECONTEXT"] == "my-context"
+    assert module.r["environ_update"]["HELM_KUBETOKEN"] == "my-api-key"
+    assert module.r["environ_update"]["HELM_NAMESPACE"] == "a-release-namespace"
+    assert module.r["environ_update"]["KUBECONFIG"]
+    assert not os.path.exists(module.r["environ_update"]["KUBECONFIG"])