CKAN worker can be called in various ways. The preferred method is a command-
line tool called
worker. It will expect to be passed a list of workers
that are supposed to be started and subscribed to a specific queue config,
worker -c config.cfg archive
Note that all workers ran by this tool will use the same queue and thus cannot subscribe to different routing keys etc.
The CKAN worker is a base class for worker tools that consume CKAN queue notifications in order to perform some type of processing based on those messages.
Worker class can be extended by implementing a single method with
the following signature::
MyWorker.consume(self, routing_key, operation, payload)
routing_key argument will usually contain type information regarding
the notification, such as the domain object in
payload (Package, Resource,
operation explains the type of action that triggered the
payload holds a serialized version of the
Worker is derived from CkanClient, it can be used to return values
to CKAN immediately. Precautions should be taken to avoid the creation of
infinite processing loops.
Worker expects to be passed a dictionary of configuration
options to access the queue and to set up a configuration. Most of these
options are the same as in CKANs configuration file: ckan.site_id,
amqp_hostname, amqp_port, amqp_user_id, and amqp_password are described
Additionally, the following keys can be set:
ckan.site_urlwill be used to set up CKANClient.
ckan.api_keywill be used to authenticate against.
Configuration by file
The CKAN worker has a configuration mechanism which can read both a config
file and command line options. It can be used by calling
ckanext.worker.configure(). The default config file name is worker.cfg,
worker.cfg.example for an example.
NOTE: When used as a command line tool, the amqp configuration is passed in as an URL of the format::