214 lines
7.7 KiB
Plaintext
214 lines
7.7 KiB
Plaintext
=head1 NAME
|
|
|
|
App::Netdisco::Manual::WritingWorkers - Developer Documentation on Worker Plugins
|
|
|
|
=head1 Introduction
|
|
|
|
L<App::Netdisco>'s plugin system allows users to write I<workers> to gather
|
|
information from network devices using different I<transports> and store
|
|
results in the database.
|
|
|
|
For example, transports might be SNMP, SSH, or HTTPS. Workers might be
|
|
combining those transports with application protocols such as SNMP, NETCONF
|
|
(OpenConfig with XML), RESTCONF (OpenConfig with JSON), eAPI, or even CLI
|
|
scraping. The combination of transport and protocol is known as a I<driver>.
|
|
|
|
Workers can be restricted to certain vendor platforms using familiar ACL
|
|
syntax. They are also attached to specific actions in Netdisco's backend
|
|
operation (discover, macsuck, etc).
|
|
|
|
See L<App::Netdisco::Worker::Plugin> for more information about worker
|
|
plugins.
|
|
|
|
=head1 Developing Workers
|
|
|
|
A worker is Perl code which is run. Therefore it can do anything you like, but
|
|
typically it will make a connection to a device, gather some data, and store
|
|
it in Netdisco's database.
|
|
|
|
App::Netdisco plugins must load the L<App::Netdisco::Worker::Plugin> module.
|
|
This exports a helper subroutine to register the worker. Here's the
|
|
boilerplate code for our example plugin module:
|
|
|
|
package App::Netdisco::Worker::Plugin::Discover::Wireless::UniFi;
|
|
|
|
use Dancer ':syntax';
|
|
use App::Netdisco::Worker::Plugin;
|
|
|
|
# worker registration code goes here, ** see below **
|
|
|
|
true;
|
|
|
|
=head1 Registering a Worker
|
|
|
|
Use the C<register_worker> helper from L<App::Netdisco::Worker::Plugin> to
|
|
register a worker:
|
|
|
|
register_worker( \%workerconf, $coderef );
|
|
|
|
For example:
|
|
|
|
register_worker({
|
|
driver => 'unifiapi',
|
|
}, sub { "worker code here" });
|
|
|
|
An explanation of the C<%workerconf> options is below. The C<$coderef> is the
|
|
main body of your worker. Your worker is run in a L<Try::Tiny> statement to
|
|
catch errors, and passed the following arguments:
|
|
|
|
$coderef->($job, \%workerconf);
|
|
|
|
The C<$job> is an instance of L<App::Netdisco::Backend::Job>. Note that this
|
|
class has a C<device> slot which may be filled, depending on the action, and
|
|
if the device is not yet discovered then the row will not yet be in storage.
|
|
The C<\%workerconf> hashref is the set of configuration parameters you used
|
|
to declare the worker (documented below).
|
|
|
|
=head2 Package Naming Convention
|
|
|
|
The package name used where the worker is declared is significant. Let's look
|
|
at the boilerplate example again:
|
|
|
|
package App::Netdisco::Worker::Plugin::Discover::Wireless::UniFi;
|
|
|
|
The package name B<must> contain C<Plugin::> and the namespace component after
|
|
that becomes the action. For example workers registered in the above package
|
|
will be run during the I<discover> backend action (that is, during a
|
|
C<discover> job). You can replace C<Discover> with other actions such as
|
|
C<Macsuck>, C<Arpnip>, C<Expire>, and C<Nbtstat>, or create your own.
|
|
|
|
The component after the action is known as the I<phase> (C<Wireless> in this
|
|
example), and is the way to override a Netdisco built-in worker, by using the
|
|
same name (plus an entry in C<%workerconf>, see below). Otherwise you can use
|
|
any valid Perl bareword for the phase.
|
|
|
|
Workers may also be registered directly to the action (C<Discover>, in this
|
|
example). This is used for very early bootstrapping code (such as first
|
|
inserting a device into the database so it can be used by subsequent phases).
|
|
|
|
=head2 C<%workerconf> Options
|
|
|
|
=over 4
|
|
|
|
=item ACL Options
|
|
|
|
Workers may have C<only> and C<no> parameters configured which use the
|
|
standard ACL syntax described in L<the settings
|
|
guide|App::Netdisco::Manual::Configuration>. The C<only> directive is
|
|
especially useful as it can restrict a worker to a given device platform or
|
|
operating system (for example Cisco IOS XR for the C<restconf> driver).
|
|
|
|
=item C<driver> (string)
|
|
|
|
The driver is a label associated with a group of workers and typically refers
|
|
to the combination of transport and application protocol. Examples include
|
|
C<snmp>, C<netconf>, C<restconf>, C<eapi>, and C<cli>. The convention is for
|
|
driver names to be lowercase.
|
|
|
|
Users will bind authentication configuration settings to drivers in their
|
|
configuration. If no driver is specified when registering a worker, it will be
|
|
run for every device and phase (such as during Expire jobs).
|
|
|
|
=item C<primary> (boolean)
|
|
|
|
When multiple workers are registered for the same phase, they will all be run.
|
|
However there is a special "I<primary>" slot for each phase in which only one
|
|
worker (the first that succeeds) is used. Most of Netdisco's built-in worker
|
|
code is registered in this way, so to override it you can use the same package
|
|
namespace and set C<primary> to be C<true>.
|
|
|
|
=back
|
|
|
|
=head2 Worker Execution and Return Code
|
|
|
|
Workers are configured as an ordered list. They are grouped by C<action> and
|
|
C<phase> (as in Package Naming Convention, above).
|
|
|
|
Workers defined in C<extra_worker_plugins> are run before those in
|
|
C<worker_plugins> so you have an opportunity to override built-in workers by
|
|
adding them to C<extra_worker_plugins> and setting C<primary> to C<true> in
|
|
the worker configuration.
|
|
|
|
The return code of the worker is significant for those configured with
|
|
C<primary> as C<true>: when the worker returns true, no other C<primary> hooks
|
|
are run for that phase.
|
|
|
|
Remember that a worker is only run if it matches the hardware platform of the
|
|
target device and the user's configuration, and is not also excluded by the
|
|
user's configuration. This filtering takes place before inspecting C<primary>.
|
|
|
|
=head2 Accessing Transports
|
|
|
|
From your worker you will want to connect to a device to gather data. This is
|
|
done using a transport protocol session (SNMP, SSH, etc). Transports are
|
|
singleton objects instantiated on demand, so they can be shared among a set of
|
|
workers that are accessing the same device.
|
|
|
|
See the documentation for each transport to find out how to access it:
|
|
|
|
=over 4
|
|
|
|
=item *
|
|
|
|
L<App::Netdisco::Transport::SNMP>
|
|
|
|
=back
|
|
|
|
=head2 Review of Terminology
|
|
|
|
In summary, Worker code is defined in a package namespace specifying the
|
|
Action and Phase, and registered as a plugin with configuration which may
|
|
specify the Driver and whether it is in the Primary slot. Access Control Lists
|
|
determine which Workers are permitted to run, and when. Here are more complete
|
|
definitions:
|
|
|
|
=over 4
|
|
|
|
=item C<action>
|
|
|
|
The highest level grouping of workers, corresponding to a Netdisco command
|
|
such as C<discover> or C<macsuck>. Workers can be registered at this level to
|
|
do really early bootstrapping work.
|
|
|
|
=item C<phase>
|
|
|
|
The next level down from C<action> for grouping workers. Phases have arbitrary
|
|
names and are visited in the order defined in the C<extra_worker_plugins>
|
|
setting list, followed by the C<worker_plugins> setting list. Workers are
|
|
usually registered at this level.
|
|
|
|
=item C<worker>
|
|
|
|
A lump of code you write which does a single clearly defined task. The package
|
|
namespace of the worker identifies the action and optionally the phase.
|
|
Workers are typically registered with some configuration settings.
|
|
|
|
=item C<driver>
|
|
|
|
A label associated with a group of workers which refers to a combination of
|
|
transport and application protocol used to connect to and communicate with the
|
|
target device. Users attach authentication configuration to specific drivers.
|
|
|
|
=item C<primary> (defaults to C<false>)
|
|
|
|
Indicates that the worker will only be run if no other C<primary> worker for
|
|
this phase has already succeeded. In this way, you can override Netdisco code
|
|
by setting this option and returning true from your worker.
|
|
|
|
=back
|
|
|
|
=head2 Database Connections
|
|
|
|
The Netdisco database is available via the C<netdisco> schema key, as below.
|
|
You can also use the C<external_databases> configuration item to set up
|
|
connections to other databases.
|
|
|
|
# plugin package
|
|
use Dancer::Plugin::DBIC;
|
|
my $set =
|
|
schema('netdisco')->resultset('Devices')
|
|
->search({vendor => 'cisco'});
|
|
|
|
=cut
|
|
|