319a824e04
rework of DataSource loading. The DataSources that are loaded are now controlled entirely via configuration file of 'datasource_list', like: datasource_list: [ "NoCloud", "OVF", "Ec2" ] Each item in that list is a "DataSourceCollection". for each item in the list, cloudinit will attempt to load: cloudinit.DataSource<item> and, failing that, DataSource<item> The module is required to have a method named 'get_datasource_list' in it that takes a single list of "dependencies" and returns a list of python classes inside the collection that can run needing only those dependencies. The dependencies are defines in DataSource.py. Currently: DEP_FILESYSTEM = "FILESYSTEM" DEP_NETWORK = "NETWORK" When 'get_datasource_list' is called for the DataSourceOVF module with [DEP_FILESYSTEM], then DataSourceOVF returns a single item list with a reference to the 'DataSourceOVF' class. When 'get_datasource_list' is called for the DataSourceOVF module with [DEP_FILESYSTEM, DEP_NETWORK], it will return a single item list with a reference to 'DataSourceOVFNet'. cloudinit will then instanciate the class and call its 'get_data' method. if the get_data method returns 'True', then it selects this class as the selected Datasource.