Oslo.config’s primary source of configuration data are plaintext, INI-like style, configuration files. With the addition of backend drivers support, it is possible to store configuration data in different places and with different formats, as long as there exists a proper driver to connect to those external sources and provide a way to fetch configuration values from them.
A backend driver implementation is divided in two main classes, a driver
class of type ConfigurationSourceDriver
and a configuration source
class of type ConfigurationSource
.
IMPORTANT: At this point, all backend drivers are only able to provide immutable values. This protects applications and services from having options in external sources mutated when they reload configuration files.
oslo_config.sources.
ConfigurationSourceDriver
¶A backend driver option for oslo.config.
For each group name listed in config_source on the DEFAULT group,
a ConfigurationSourceDriver
is responsible for creating one new
instance of a ConfigurationSource
. The proper driver class to be
used is selected based on the driver option inside each one of the
groups listed in config_source and loaded through entry points managed by
stevedore using the namespace oslo.config.driver:
[DEFAULT]
config_source = source1
config_source = source2
...
[source1]
driver = remote_file
...
[source2]
driver = castellan
...
Each specific driver knows all the available options to properly instatiate a ConfigurationSource using the values comming from the given group in the open_source_from_opt_group() method and is able to generate sample config through the list_options_for_discovery() method.
list_options_for_discovery
()¶Return the list of options available to configure a new source.
Drivers should advertise all supported options in this method for the purpose of sample generation by oslo-config-generator.
For an example on how to implement this method you can check the remote_file driver at oslo_config.sources._uri.URIConfigurationSourceDriver.
Returns: | a list of supported options of a ConfigurationSource. |
---|
open_source_from_opt_group
(conf, group_name)¶Return an open configuration source.
Uses group_name to find the configuration settings for the new source and then open the configuration source and return it.
If a source cannot be open, raises an appropriate exception.
Parameters: |
|
---|---|
Returns: | an instance of a subclass of ConfigurationSource |
oslo_config.sources.
ConfigurationSource
¶A configuration source option for oslo.config.
A configuration source is able to fetch configuration values based on a (group, option) key from an external source that supports key-value mapping such as INI files, key-value stores, secret stores, and so on.
get
(group_name, option_name, opt)¶Return the value of the option from the group.
Parameters: |
|
---|---|
Returns: | A tuple (value, location) where value is the option value or oslo_config.sources._NoValue if the (group, option) is not present in the source, and location is a LocationInfo. |
oslo_config.sources.
ConfigurationSource
Bases: object
A configuration source option for oslo.config.
A configuration source is able to fetch configuration values based on a (group, option) key from an external source that supports key-value mapping such as INI files, key-value stores, secret stores, and so on.
get
(group_name, option_name, opt)Return the value of the option from the group.
Parameters: |
|
---|---|
Returns: | A tuple (value, location) where value is the option value or oslo_config.sources._NoValue if the (group, option) is not present in the source, and location is a LocationInfo. |
oslo_config.sources.
ConfigurationSourceDriver
Bases: object
A backend driver option for oslo.config.
For each group name listed in config_source on the DEFAULT group,
a ConfigurationSourceDriver
is responsible for creating one new
instance of a ConfigurationSource
. The proper driver class to be
used is selected based on the driver option inside each one of the
groups listed in config_source and loaded through entry points managed by
stevedore using the namespace oslo.config.driver:
[DEFAULT]
config_source = source1
config_source = source2
...
[source1]
driver = remote_file
...
[source2]
driver = castellan
...
Each specific driver knows all the available options to properly instatiate a ConfigurationSource using the values comming from the given group in the open_source_from_opt_group() method and is able to generate sample config through the list_options_for_discovery() method.
list_options_for_discovery
()Return the list of options available to configure a new source.
Drivers should advertise all supported options in this method for the purpose of sample generation by oslo-config-generator.
For an example on how to implement this method you can check the remote_file driver at oslo_config.sources._uri.URIConfigurationSourceDriver.
Returns: | a list of supported options of a ConfigurationSource. |
---|
open_source_from_opt_group
(conf, group_name)Return an open configuration source.
Uses group_name to find the configuration settings for the new source and then open the configuration source and return it.
If a source cannot be open, raises an appropriate exception.
Parameters: |
|
---|---|
Returns: | an instance of a subclass of ConfigurationSource |
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