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

plugins/module_utils/helm.py

@@ -0,0 +1,119 @@
+# -*- 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
+
+
+from contextlib import contextmanager
+import os
+import tempfile
+import traceback
+
+from ansible.module_utils.basic import missing_required_lib
+
+
+try:
+    import yaml
+    HAS_YAML = True
+except ImportError:
+    YAML_IMP_ERR = traceback.format_exc()
+    HAS_YAML = False
+
+
+@contextmanager
+def prepare_helm_environ_update(module):
+    environ_update = {}
+    file_to_cleam_up = None
+    kubeconfig_path = module.params.get('kubeconfig')
+    if module.params.get('kube_context') is not None:
+        environ_update["HELM_KUBECONTEXT"] = module.params.get('kube_context')
+    if module.params.get('release_namespace'):
+        environ_update["HELM_NAMESPACE"] = module.params.get('release_namespace')
+    if module.params.get("api_key"):
+        environ_update["HELM_KUBETOKEN"] = module.params["api_key"]
+    if module.params.get("host"):
+        environ_update["HELM_KUBEAPISERVER"] = module.params["host"]
+    if module.params.get("validate_certs") is False or module.params.get("ca_cert"):
+        kubeconfig_path = write_temp_kubeconfig(
+            module.params["host"],
+            validate_certs=module.params["validate_certs"],
+            ca_cert=module.params["ca_cert"])
+        file_to_cleam_up = kubeconfig_path
+    if kubeconfig_path is not None:
+        environ_update["KUBECONFIG"] = kubeconfig_path
+
+    try:
+        yield environ_update
+    finally:
+        if file_to_cleam_up:
+            os.remove(file_to_cleam_up)
+
+
+def run_helm(module, command, fails_on_error=True):
+    if not HAS_YAML:
+        module.fail_json(msg=missing_required_lib("PyYAML"), exception=YAML_IMP_ERR)
+
+    with prepare_helm_environ_update(module) as environ_update:
+        rc, out, err = module.run_command(command, environ_update=environ_update)
+    if fails_on_error and rc != 0:
+        module.fail_json(
+            msg="Failure when executing Helm command. Exited {0}.\nstdout: {1}\nstderr: {2}".format(rc, out, err),
+            stdout=out,
+            stderr=err,
+            command=command,
+        )
+    return rc, out, err
+
+
+def get_values(module, command, release_name):
+    """
+    Get Values from deployed release
+    """
+    if not HAS_YAML:
+        module.fail_json(msg=missing_required_lib("PyYAML"), exception=YAML_IMP_ERR)
+
+    get_command = command + " get values --output=yaml " + release_name
+
+    rc, out, err = run_helm(module, get_command)
+    # Helm 3 return "null" string when no values are set
+    if out.rstrip("\n") == "null":
+        return {}
+    return yaml.safe_load(out)
+
+
+def write_temp_kubeconfig(server, validate_certs=True, ca_cert=None):
+    # Workaround until https://github.com/helm/helm/pull/8622 is merged
+    content = {
+        "apiVersion": "v1",
+        "kind": "Config",
+        "clusters": [
+            {
+                "cluster": {
+                    "server": server,
+                },
+                "name": "generated-cluster"
+            }
+        ],
+        "contexts": [
+            {
+                "context": {
+                    "cluster": "generated-cluster"
+                },
+                "name": "generated-context"
+            }
+        ],
+        "current-context": "generated-context"
+    }
+
+    if not validate_certs:
+        content["clusters"][0]["cluster"]["insecure-skip-tls-verify"] = True
+    if ca_cert:
+        content["clusters"][0]["cluster"]["certificate-authority"] = ca_cert
+
+    _fd, file_name = tempfile.mkstemp()
+    with os.fdopen(_fd, 'w') as fp:
+        yaml.dump(content, fp)
+    return file_name