======================= Working with NetDevices ======================= :class:`~trigger.netdevices.NetDevices` is the core of Trigger's device interaction. Anything that communicates with devices relies on the metadata stored within :class:`~trigger.netdevices.NetDevice` objects. netdevices.xml ============== NetDevices reads in your ``netdevices.xml`` file that should be a dump of relevant metadata fields from your CMDB. If you don't have a CMDB, then you're going to have to populate this file manually. But you're a Python programmer, right? So you can come up with something spiffy! Here is what the ``netdevices.xml`` file bundled with the Trigger source code looks like: .. code-block:: xml PRODUCTION 0000012345 tacacs 0101010101 1234578 Data Center 16ZZ ROUTER boguspassword 2010-07-19 19:56:32.0 1 1 1 INSTALLED M40 INTERNET BACKBONE ROUTER JUNIPER M40-B-AC test1-abc.net.aol.com nobody@aol.net 17 Data Center Data Center C ts1.oob.aol.com ts1 5 5005 MONITORED 12345678 - Network Engineering Test Lab CR10 987654321 LAB ... We plan to add support for different input sources including JSON, Sqlite, or "other" in the near future, but for now this is it. By default the location of ``netdevices.xml`` can be specified one of two ways: 1. Specifing the path in the ``NETDEVICESXML_FILE`` environment variable, or; 2. modifying the value of of ``settings.NETDEVICESXML_FILE``. Getting Started =============== First things first, you must instantiate NetDevices. It has three things it requires before you can properly do this: 1. The ``netdevices.xml`` file must be readable and must properly parse (see above); 2. An instance of Redis. 3. The path to ``autoacl.py`` must be valid, and must properly parse. How it works ------------ The NetDevices object itself is an immutable, dictionary-like Singleton_ object. If you don't know what a Singleton is, it means that the actual there can only really only be one instance in any program. The actual instance object itself an instance of the inner :class:`~trigger.netdevices.NetDevices._actual` class which is stored in the module object as ``NetDevices._Singleton``. This is done as a performance boost because many Trigger components require a NetDevices instance, and if we had to keep creating new ones, we'd be waiting forever each time one had to parse ``netdevices.xml`` all over again. Upon startup, each ```` element found within ``netdevices.xml`` is used to create a ``NetDevice`` object. This object pulls in ACL associations from AclsDB. .. _Singleton: http://en.wikipedia.org/wiki/Singleton_pattern The Singleton Pattern ~~~~~~~~~~~~~~~~~~~~~ The NetDevices module object has a ``_Singleton`` attribute that defaults to ``None``. Upon creating an instance, this is populated with the ``NetDevices._actual`` instance:: >>> nd = NetDevices() >>> nd._Singleton >>> NetDevices._Singleton This is how new instances are prevented. Whenever you create a new reference by instantiating NetDevices again, what you are really doing is creating a reference to ``NetDevices._Singleton``:: >>> other_nd = NetDevices() >>> other_nd._Singleton >>> nd._Singleton is other_nd._Singleton True The only time this would be an issue is if you needed to change the actual contents of your object (such as when debugging ``netdevices.xml`` or passing ``production_only=False``). If you need to do this, set the value to ``None``:: >>> NetDevices._Singleton = None Then the next call to ``NetDevices()`` will start from scratch. Keep in mind because of this pattern it is not easy to have more than one instance (there are ways but we're not going to list them here!). All existing instances will inherit the value of ``NetDevices._Singleton``:: >>> third_nd = NetDevices(production_only=False) >>> third_nd._Singleton >>> nd._Singleton >>> third_nd._Singleton is nd._Singleton True Instantiating NetDevices ======================== Throughout the Trigger code, the convention when instantiating and referencing a NetDevices instance, is to assign it to the variable ``nd``. All examples will use this, so keep that in mind:: >>> from trigger.netdevices import NetDevices >>> nd = NetDevices() >>> len(nd) 3 By default, this only includes any devices for which ``adminStatus`` (aka administrative status) is ``PRODUCTION``. This means that the device is used in your production environment. If you would like you get all devices regardless of ``adminStatus``, you must pass ``production_only=False`` to the constructor:: >>> from trigger.netdevices import NetDevices >>> nd = NetDevices(production_only=False) >>> len(nd) 4 The included sample ``netdevices.xml`` contains one device that is marked as ``NON-PRODUCTION``. What's in a NetDevice? ====================== A :class:`~trigger.netdevices.NetDevice` object has a number of attributes you can use creatively to correlate or identify them:: >>> dev = nd.find('test1-abc') >>> dev Printing it displays the hostname:: >>> print dev test1-abc.net.aol.com You can dump the values:: >>> dev.dump() Hostname: test1-abc.net.aol.com Owning Org.: 12345678 - Network Engineering Owning Team: Data Center OnCall Team: Data Center Manufacturer: JUNIPER Make: M40 INTERNET BACKBONE ROUTER Model: M40-B-AC Type: ROUTER Location: LAB CR10 16ZZ Project: Test Lab Serial: 987654321 Asset Tag: 0000012345 Budget Code: 1234578 (Data Center) Admin Status: PRODUCTION Lifecycle Status: INSTALLED Operation Status: MONITORED Last Updated: 2010-07-19 19:56:32.0 You can reference them as attributes:: >>> dev.nodeName, dev.manufacturer, dev.deviceType ('test1-abc.net.aol.com', 'JUNIPER', 'ROUTER') There are some special methods to perform identity tests:: >>> dev.is_router(), dev.is_switch(), dev.is_firewall() (True, False, False) You can view the ACLs assigned to the device:: >>> dev.explicit_acls set(['abc123']) >>> dev.implicit_acls set(['juniper-router.policer', 'juniper-router-protect']) >>> dev.acls set(['juniper-router.policer', 'juniper-router-protect', 'abc123']) Or get the next time it's ok to make changes to this device (more on this later):: >>> dev.bounce.next_ok('green') datetime.datetime(2011, 7, 13, 9, 0, tzinfo=) >>> print dev.bounce.status() red Searching for devices ===================== Like a dictionary ----------------- Since the object is like a dictionary, you may reference devices as keys by their hostnames:: >>> nd {'test2-abc.net.aol.com': , 'test1-abc.net.aol.com': , 'lab1-switch.net.aol.com': , 'fw1-xyz.net.aol.com': } >>> nd['test1-abc.net.aol.com'] You may also perform any other operations to iterate devices as you would with a dictionary (``.keys()``, ``.itervalues()``, etc.). Special methods --------------- There are a number of ways you can search for devices. In all cases, you are returned a list. The simplest usage is just to list all devices:: >>> nd.all() [, , , ] Using ``all()`` is going to be very rare, as you're more likely to work with a subset of your devices. Find a device by its shortname (minus the domain):: >>> nd.find('test1-abc') List devices by type (switches, routers, or firewalls):: >>> nd.list_routers() [, ] >>> nd.list_switches() [] >>> nd.list_firewalls() [] Perform a case-sensitive search on any field (it defaults to ``nodeName``):: >>> nd.search('test') [, ] >>> nd.search('test2') [] >>> nd.search('NON-PRODUCTION', 'adminStatus') [] Or you could just roll your own list comprehension to do the same thing:: >>> [d for d in nd.all() if d.adminStatus == 'NON-PRODUCTION'] [] Perform a case-INsenstive search on any number of fields as keyword arguments:: >>> nd.match(oncallname='data center', adminstatus='non') [] >>> nd.match(manufacturer='netscreen') [] Helper function --------------- Another nifty tool within the module is :func:`~trigger.netdevices.device_match`, which returns a NetDevice object:: >>> from trigger.netdevices import device_match >>> device_match('test') 2 possible matches found for 'test': [ 1] test1-abc.net.aol.com [ 2] test2-abc.net.aol.com [ 0] Exit Enter a device number: 2 If there are multiple matches, it presents a prompt and lets you choose, otherwise it chooses for you:: >>> device_match('fw') Matched 'fw1-xyz.net.aol.com'.