add initial support for Arista eAPI

This commit adds the shared module support for Arisat EOS devices
running eAPI.  The shared module builds on top of module_utils/urls.py.

lib/ansible/module_utils/eapi.py

@@ -0,0 +1,155 @@
+#
+# (c) 2015 Peter Sprygada, <psprygada@ansible.com>
+#
+# This file is part of Ansible
+#
+# Ansible 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.
+#
+# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
+#
+"""
+This module adds shared support for Arista EOS devices using eAPI over
+HTTP/S transport.   It is built on module_utils/urls.py which is required
+for proper operation.
+
+In order to use this module, include it as part of a custom
+module as shown below.
+
+** Note: The order of the import statements does matter. **
+
+from ansible.module_utils.basic import *
+from ansible.module_utils.urls import *
+from ansible.module_utils.eapi import *
+
+The eapi module provides the following common argument spec:
+
+    * host (str) - [Required] The IPv4 address or FQDN of the network device
+
+    * port (str) - Overrides the default port to use for the HTTP/S
+        connection.  The default values are 80 for HTTP and
+        443 for HTTPS
+
+    * url_username (str) - [Required] The username to use to authenticate
+        the HTTP/S connection.  Aliases: username
+
+    * url_password (str) - [Required] The password to use to authenticate
+        the HTTP/S connection.  Aliases: password
+
+    * use_ssl (bool) - Specifies whether or not to use an encrypted (HTTPS)
+        connection or not.  The default value is False.
+
+    * enable_mode (bool) - Specifies whether or not to enter `enable` mode
+        prior to executing the command list.  The default value is True
+
+    * enable_password (str) - The password for entering `enable` mode
+        on the switch if configured.
+
+In order to communicate with Arista EOS devices, the eAPI feature
+must be enabled and configured on the device.
+
+"""
+def eapi_argument_spec(spec=None):
+    """Creates an argument spec for working with eAPI
+    """
+    arg_spec = url_argument_spec()
+    arg_spec.update(dict(
+        host=dict(required=True),
+        port=dict(),
+        url_username=dict(required=True, aliases=['username']),
+        url_password=dict(required=True, aliases=['password']),
+        use_ssl=dict(default=True, type='bool'),
+        enable_mode=dict(default=True, type='bool'),
+        enable_password=dict()
+    ))
+    if spec:
+        arg_spec.update(spec)
+    return arg_spec
+
+def eapi_url(module):
+    """Construct a valid Arist eAPI URL
+    """
+    if module.params['use_ssl']:
+        proto = 'https'
+    else:
+        proto = 'http'
+    host = module.params['host']
+    url = '{}://{}'.format(proto, host)
+    if module.params['port']:
+        url = '{}:{}'.format(url, module.params['port'])
+    return '{}/command-api'.format(url)
+
+def to_list(arg):
+    """Convert the argument to a list object
+    """
+    if isinstance(arg, (list, tuple)):
+        return list(arg)
+    elif arg is not None:
+        return [arg]
+    else:
+        return []
+
+def eapi_body(commands, encoding, reqid=None):
+    """Create a valid eAPI JSON-RPC request message
+    """
+    params = dict(version=1, cmds=to_list(commands), format=encoding)
+    return dict(jsonrpc='2.0', id=reqid, method='runCmds', params=params)
+
+def eapi_enable_mode(module):
+    """Build commands for entering `enable` mode on the switch
+    """
+    if module.params['enable_mode']:
+        passwd = module.params['enable_password']
+        if passwd:
+            return dict(cmd='enable', input=passwd)
+        else:
+            return 'enable'
+
+def eapi_command(module, commands, encoding='json'):
+    """Send an ordered list of commands to the device over eAPI
+    """
+    commands = to_list(commands)
+    url = eapi_url(module)
+
+    enable = eapi_enable_mode(module)
+    if enable:
+        commands.insert(0, enable)
+
+    data = eapi_body(commands, encoding)
+    data = module.jsonify(data)
+
+    headers = {'Content-Type': 'application/json-rpc'}
+
+    response, headers = fetch_url(module, url, data=data, headers=headers,
+                                  method='POST')
+
+    if headers['status'] != 200:
+        module.fail_json(**headers)
+
+    response = module.from_json(response.read())
+    if 'error' in response:
+        err = response['error']
+        module.fail_json(msg='json-rpc error', **err)
+
+    if enable:
+        response['result'].pop(0)
+
+    return response['result'], headers
+
+def eapi_configure(module, commands):
+    """Send configuration commands to the device over eAPI
+    """
+    commands.insert(0, 'configure')
+    response, headers = eapi_command(module, commands)
+    response.pop(0)
+    return response, headers
+
+