[CORD-1273] Base structure for XOS-Config
Change-Id: I27f0b6664127ae2b26a1e7f489c70d5d32b73c3c
diff --git a/lib/xos-config/xosconfig/config.py b/lib/xos-config/xosconfig/config.py
new file mode 100644
index 0000000..e58477c
--- /dev/null
+++ b/lib/xos-config/xosconfig/config.py
@@ -0,0 +1,172 @@
+import os
+import sys
+import yaml
+import requests
+import default
+from pykwalify.core import Core as PyKwalify
+
+DEFAULT_CONFIG_FILE = "/opt/xos/config.yaml"
+INITIALIZED = False
+CONFIG = {}
+
+class Config:
+ """
+ XOS Configuration APIs
+ """
+
+ @staticmethod
+ def init(config_file=DEFAULT_CONFIG_FILE):
+ global INITIALIZED
+ global CONFIG
+ # the config module can be initialized only one
+ if INITIALIZED:
+ raise Exception('[XOS-Config] Module already initialized')
+ INITIALIZED = True
+
+ # if XOS-CONFIG is defined override the config_file
+ if os.environ.get('XOS-CONFIG'):
+ config_file = os.environ['XOS-CONFIG']
+
+ # if a -C parameter is set in the cli override the config_file
+ # FIXME shouldn't this stay in whatever module call this one? and then just pass the file to the init method
+ if Config.get_cli_param(sys.argv):
+ config_file = Config.get_cli_param(sys.argv)
+
+ CONFIG = Config.read_config(config_file)
+
+ @staticmethod
+ def clear():
+ global INITIALIZED
+ INITIALIZED = False
+
+ @staticmethod
+ def validate_config_format(config_file):
+ schema = os.path.abspath(os.path.dirname(os.path.realpath(__file__)) + '/config-schema.yaml')
+ c = PyKwalify(source_file=config_file, schema_files=[schema])
+ c.validate(raise_exception=True)
+
+ @staticmethod
+ def get_cli_param(args):
+ last = None
+ for arg in args:
+ if last == '-C':
+ return arg
+ last = arg
+
+ @staticmethod
+ def read_config(config_file):
+ """
+ Read the configuration file and return a dictionary
+ :param config_file: string
+ :return: dict
+ """
+ if not os.path.exists(config_file):
+ raise Exception('[XOS-Config] Config file not found at: %s' % config_file)
+
+ try:
+ Config.validate_config_format(config_file)
+ except Exception, e:
+ raise Exception('[XOS-Config] The config format is wrong: %s' % e.msg)
+
+ with open(config_file, 'r') as stream:
+ return yaml.safe_load(stream)
+
+ @staticmethod
+ def get(query):
+ """
+ Read a parameter from the config
+ :param query: a dot separated selector for configuration options (eg: database.username)
+ :return: the requested parameter in any format the parameter is specified
+ """
+ global INITIALIZED
+ global CONFIG
+
+ if not INITIALIZED:
+ raise Exception('[XOS-Config] Module has not been initialized')
+
+ val = Config.get_param(query, CONFIG)
+ if not val:
+ val = Config.get_param(query, default.DEFAULT_VALUES)
+ if not val:
+ raise Exception('[XOS-Config] Config does not have a value (or a default) parameter %s' % query)
+ return val
+
+ @staticmethod
+ def get_param(query, config):
+ """
+ Search for a parameter in config's first level, other call get_nested_param
+ :param query: a dot separated selector for configuration options (eg: database.username)
+ :param config: the config source to read from (can be the config file or the defaults)
+ :return: the requested parameter in any format the parameter is specified
+ """
+ keys = query.split('.')
+ if len(keys) == 1:
+ key = keys[0]
+ if not config.has_key(key):
+ return None
+ return config[key]
+ else:
+ return Config.get_nested_param(keys, config)
+
+ @staticmethod
+ def get_nested_param(keys, config):
+ """
+
+ :param keys: a list of descending selector
+ :param config: the config source to read from (can be the config file or the defaults)
+ :return: the requested parameter in any format the parameter is specified
+ """
+ param = config
+ for k in keys:
+ if not param.has_key(k):
+ return None
+ param = param[k]
+ return param
+
+ @staticmethod
+ def get_service_list():
+ """
+ Query registrator to get the list of services
+ NOTE: we assume that consul is a valid URL
+ :return: a list of service names
+ """
+ service_dict = requests.get('http://consul:8500/v1/catalog/services').json()
+ service_list = []
+ for s in service_dict:
+ service_list.append(s)
+ return service_list
+
+ @staticmethod
+ def get_service_info(service_name):
+ """
+ Query registrator to get the details about a service
+ NOTE: we assume that consul is a valid URL
+ :param service_name: the name of the service, can be retrieved from get_service_list
+ :return: the informations about a service
+ """
+ response = requests.get('http://consul:8500/v1/catalog/service/%s' % service_name)
+ if not response.ok:
+ raise Exception('[XOS-Config] Registrator is down')
+ service = response.json()
+ if not service or len(service) == 0:
+ raise Exception('[XOS-Config] The service missing-service looking for does not exist')
+ return {
+ 'name': service[0]['ServiceName'],
+ 'url': service[0]['ServiceAddress'],
+ 'port': service[0]['ServicePort']
+ }
+
+ @staticmethod
+ def get_service_endpoint(service_name):
+ """
+ Query registrator to get the details about a service and return the endpoint in for of a string
+ :param service_name: the name of the service, can be retrieved from get_service_list
+ :return: the endpoint of the service
+ """
+ service = Config.get_service_info(service_name)
+ return 'http://%s:%s' % (service['url'], service['port'])
+
+# NOTE is this needed if this package is not meant to be execute from the CLI?
+if __name__ == '__main__':
+ config = Config()
+ config.init()
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