Move API call to function and implement keys

Move all API calls to a new common function called call_api to
facilitate easier future changes. Use this function to implement API key
handling via request header value as well as integrate the request URI
generation and debug output handling.

Closes #65

client-cli/cli_lib/common.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+
+# common.py - PVC CLI client function library, Common functions
+# Part of the Parallel Virtual Cluster (PVC) system
+#
+#    Copyright (C) 2018-2019 Joshua M. Boniface <joshua@boniface.me>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+###############################################################################
+
+import requests
+import click
+
+def call_api(config, operation, request_uri, params=None, data=None):
+    # Craft the URI
+    uri = '{}://{}{}{}'.format(
+        config['api_scheme'],
+        config['api_host'],
+        config['api_prefix'],
+        request_uri
+    )
+    # Craft the authentication header if required
+    if config['api_key']:
+        headers = {'X-Api-Key': config['api_key']}
+    else:
+        headers = None
+    # Determine the request type and hit the API
+    if operation == 'get':
+        response = requests.get(
+            uri,
+            headers=headers,
+            params=params,
+            data=data
+        )
+    if operation == 'post':
+        response = requests.post(
+            uri,
+            headers=headers,
+            params=params,
+            data=data
+        )
+    if operation == 'put':
+        response = requests.put(
+            uri,
+            headers=headers,
+            params=params,
+            data=data
+        )
+    if operation == 'patch':
+        response = requests.patch(
+            uri,
+            headers=headers,
+            params=params,
+            data=data
+        )
+    if operation == 'delete':
+        response = requests.delete(
+            uri,
+            headers=headers,
+            params=params,
+            data=data
+        )
+    # Display debug output
+    if config['debug']:
+        click.echo('API endpoint: {}'.format(uri), err=True)
+        click.echo('Response code: {}'.format(response.status_code), err=True)
+        click.echo('Response headers: {}'.format(response.headers), err=True)
+    # Return the response object
+    return response
+