79 lines
2.1 KiB
ReStructuredText
79 lines
2.1 KiB
ReStructuredText
|
===============
|
||
|
|
Scope fetcher
|
||
|
|
===============
|
||
|
|
|
||
|
|
The fetcher retrieves a list of scopes to rate. These scopes are then passed to
|
||
|
|
the collector, in combination with each metric type.
|
||
|
|
|
||
|
|
Implementation
|
||
|
|
==============
|
||
|
|
|
||
|
|
Fetchers are extremely simple. A custom fetcher must implement the following
|
||
|
|
class:
|
||
|
|
|
||
|
|
.. autoclass:: cloudkitty.fetcher.BaseFetcher
|
||
|
|
:members: get_tenants
|
||
|
|
|
||
|
|
The ``get_tenants`` method takes no parameters and returns a list of unique
|
||
|
|
scope_ids, represented as ``str``.
|
||
|
|
|
||
|
|
The name of the new fetcher must be specified as a class attribute.
|
||
|
|
|
||
|
|
Options for the new fetcher must be registered under the ``fetcher_<name>``
|
||
|
|
config section.
|
||
|
|
|
||
|
|
A new scope fetcher must be implemented in a new module, in
|
||
|
|
``cloudkitty.fetcher.<name>.py``. Its class must be called ``<Name>Fetcher``.
|
||
|
|
|
||
|
|
An entrypoint must be registered for new fetchers. This is done in the
|
||
|
|
``setup.cfg`` file, located at the root of the repository:
|
||
|
|
|
||
|
|
.. code-block:: ini
|
||
|
|
|
||
|
|
cloudkitty.fetchers =
|
||
|
|
keystone = cloudkitty.fetcher.keystone:KeystoneFetcher
|
||
|
|
source = cloudkitty.fetcher.source:SourceFetcher
|
||
|
|
# [...]
|
||
|
|
custom = cloudkitty.fetcher.custom:CustomFetcher
|
||
|
|
|
||
|
|
Example
|
||
|
|
=======
|
||
|
|
|
||
|
|
The most simple scope fetcher is the ``SourceFetcher``. It simply returns a
|
||
|
|
list of scopes read from the configuration file:
|
||
|
|
|
||
|
|
.. code-block:: python
|
||
|
|
|
||
|
|
# In cloudkitty/fetcher/source.py
|
||
|
|
from oslo_config import cfg
|
||
|
|
|
||
|
|
from cloudkitty import fetcher
|
||
|
|
|
||
|
|
FETCHER_SOURCE_OPTS = 'fetcher_source'
|
||
|
|
|
||
|
|
fetcher_source_opts = [
|
||
|
|
cfg.ListOpt(
|
||
|
|
'sources',
|
||
|
|
default=list(),
|
||
|
|
help='list of source identifiers',
|
||
|
|
),
|
||
|
|
]
|
||
|
|
|
||
|
|
# Registering the 'sources' option in the 'fetcher_source' option
|
||
|
|
cfg.CONF.register_opts(fetcher_source_opts, FETCHER_SOURCE_OPTS)
|
||
|
|
|
||
|
|
CONF = cfg.CONF
|
||
|
|
|
||
|
|
|
||
|
|
class SourceFetcher(fetcher.BaseFetcher):
|
||
|
|
|
||
|
|
# Defining the name of the fetcher
|
||
|
|
name = 'source'
|
||
|
|
|
||
|
|
# Returning the list of scopes read from the configuration file
|
||
|
|
def get_tenants(self):
|
||
|
|
return CONF.fetcher_source.sources
|
||
|
|
|
||
|
|
|
||
|
|
More complex examples can be found in the ``cloudkitty/fetcher`` directory.
|