CORD-654 configure MAAS via ansible module

Change-Id: I9f1b3b83b41d2cf1e87660d4a50fd3267ad1679a
diff --git a/library/maas_cluster.py b/library/maas_cluster.py
new file mode 100644
index 0000000..5a3f4b7
--- /dev/null
+++ b/library/maas_cluster.py
@@ -0,0 +1,188 @@
+#!/usr/bin/python
+
+DOCUMENTATION = '''
+---
+module: maas_cluster
+short_description: Manage MAAS Clusters Interfaces
+options:
+  maas:
+    description:
+      - URL of MAAS server
+    default: http://localhost/MAAS/api/1.0/
+  key:
+    description:
+      - MAAS API key
+    required: yes
+  name:
+    description:
+      - name of the cluster
+    required: yes
+  status:
+    description:
+      - indicates the enabled state of the cluster
+    choices: ['enabled', 'disabled']
+    default: enabled
+  domain:
+    description:
+      - DNS zone name
+    required: no
+  state:
+    description:
+      - possible states for this cluster
+    choices: ['present', 'query']
+    default: present
+
+requirements: [ipaddress, requests_oauthlib, maasclient]
+author: David Bainbridge
+'''
+
+EXAMPLES = '''
+examples:
+  maas_cluster:
+    maas: http://my.maas.server.com/MAAS/api/1.0/
+    key: 'xBvr9dx5k7S52myufC:fqBXV7hJgXegNZDw9c:K8hsmL47XjAppfQy2pDVW7G49p6PELgp'
+    name: MyCluster
+    status: enabled
+    domain: company.com
+    state: present
+
+  maas_cluster:
+    maas: http://my.maas.server.com/MAAS/api/1.0/
+    key: 'xBvr9dx5k7S52myufC:fqBXV7hJgXegNZDw9c:K8hsmL47XjAppfQy2pDVW7G49p6PELgp'
+    name: MyDeadCluster
+    state: query
+'''
+
+import sys
+import json
+import ipaddress
+import requests
+from maasclient.auth import MaasAuth
+from maasclient import MaasClient
+
+# For some reason the maasclient doesn't provide a put method. So
+# we will add it here
+def put(client, url, params=None):
+    return requests.put(url=client.auth.api_url + url,
+                        auth=client._oauth(), data=params)
+
+# Attempt to interpret the given value as a JSON object, if that fails
+# just return it as a string
+def string_or_object(val):
+    try:
+        return json.loads(val)
+    except:
+        return val
+
+# Return a copy of the given dictionary with any `null` valued entries
+# removed
+def remove_null(d_in):
+    d = d_in.copy()
+    to_remove = []
+    for k in d.keys():
+        if d[k] == None:
+            to_remove.append(k)
+    for k in to_remove:
+        del d[k]
+    return d
+
+# Deterine if two dictionaries are different
+def different(have, want):
+    have_keys = have.keys()
+    for key in want.keys():
+        if (key in have_keys and want[key] != have[key]) or key not in have_keys:
+            return True
+    return False
+
+# Get an cluster from MAAS using its name, if not found return None
+def get_cluster(maas, name):
+    res = maas.get('/nodegroups/', dict(op='list'))
+    if res.ok:
+        for ng in json.loads(res.text):
+            if ng['cluster_name'] == name:
+                return ng
+    return None
+
+def update_cluster(maas, have, want):
+    merged = have.copy()
+    merged.update(want)
+    res = put(maas, '/nodegroups/%s/' % merged['uuid'], merged)
+    if res.ok:
+        return { 'error': False, 'status': get_cluster(maas, merged['cluster_name']) }
+    return { 'error': True, 'status': string_or_object(res.text) }
+
+def main():
+    module = AnsibleModule(
+        argument_spec = dict(
+            maas=dict(default='http://localhost/MAAS/api/1.0/'),
+            key=dict(required=True),
+            name=dict(required=True),
+            status=dict(default='enabled', choices=['enabled', 'disabled']),
+            domain=dict(required=False),
+            state=dict(default='present', choices=['present', 'query'])
+        ),
+        supports_check_mode = False
+    )
+
+    maas = module.params['maas']
+    key = module.params['key']
+    state = module.params['state']
+
+    status_map = {
+        'enabled': 1,
+        'disabled': 2
+    }
+
+    # Construct a sparsely populate desired state
+    desired = remove_null({
+        'cluster_name': module.params['name'],
+        'status': status_map[module.params['status']],
+        'name' : module.params['domain'],
+    })
+
+    # Authenticate into MAAS
+    auth = MaasAuth(maas, key)
+    maas = MaasClient(auth)
+
+    # Attempt to get the cluster from MAAS
+    cluster = get_cluster(maas, desired['cluster_name'])
+
+    # Actions if the cluster does not currently exist
+    if not cluster:
+        if state == 'query':
+            # If this is a query, returne it is not found
+            module.exit_json(changed=False, found=False)
+        elif state == 'present':
+            # Not able to create clusters via the API
+            module.fail_json(msg='Named cluster does not exist and clusters cannot be programatically created')
+        else:
+            # If this should be absent, then we are done and in the desired state
+            module.exit_json(changed=False)
+
+        # Done with clusters does not exists actions
+        return
+
+    # Actions if the cluster does exist
+    if state == 'query':
+        # If this is a query, return the cluster
+        module.exit_json(changed=False, found=True, cluster=cluster)
+    elif state == 'present':
+        # If we want this to exists check to see if this is different and
+        # needs updated
+        if different(cluster, desired):
+            res = update_cluster(maas, cluster, desired)
+            if res['error']:
+                module.fail_json(msg=res['status'])
+            else:
+                module.exit_json(changed=True, cluster=res['status'])
+        else:
+            # No differences, to nothing to change
+            module.exit_json(changed=False, cluster=cluster)
+    else:
+        # Not able to delete clusters via the API
+        module.fail_json(msg='Named cluster exists and clusters cannot be programmatically deleted')
+
+# this is magic, see lib/ansible/module_common.py
+#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
+if __name__ == '__main__':
+    main()