move settings under uncloud.common

uncloud/common/settings.py

@@ -0,0 +1,128 @@
+import configparser
+import logging
+import sys
+import os
+
+from datetime import datetime
+
+from uncloud.common.etcd_wrapper import Etcd3Wrapper
+
+logger = logging.getLogger(__name__)
+
+
+class CustomConfigParser(configparser.RawConfigParser):
+    def __getitem__(self, key):
+        try:
+            result = super().__getitem__(key)
+        except KeyError as err:
+            raise KeyError(
+                'Key \'{}\' not found in configuration. Make sure you configure uncloud.'.format(
+                    key
+                )
+            ) from err
+        else:
+            return result
+
+
+class Settings(object):
+    def __init__(self, config_key='/uncloud/config/'):
+        conf_name = 'uncloud.conf'
+        conf_dir = os.environ.get(
+            'UCLOUD_CONF_DIR', os.path.expanduser('~/uncloud/')
+        )
+        self.config_file = os.path.join(conf_dir, conf_name)
+        self.config_parser = CustomConfigParser(allow_no_value=True)
+        self.config_key = config_key
+
+        # this is used to cache config from etcd for 1 minutes. Without this we
+        # would make a lot of requests to etcd which slows down everything.
+        self.last_config_update = datetime.fromtimestamp(0)
+
+        self.read_internal_values()
+        try:
+            self.config_parser.read(self.config_file)
+        except Exception as err:
+            logger.error('%s', err)
+
+    def get_etcd_client(self):
+        args = tuple()
+        try:
+            kwargs = {
+                'host': self.config_parser.get('etcd', 'url'),
+                'port': self.config_parser.get('etcd', 'port'),
+                'ca_cert': self.config_parser.get('etcd', 'ca_cert'),
+                'cert_cert': self.config_parser.get('etcd', 'cert_cert'),
+                'cert_key': self.config_parser.get('etcd', 'cert_key'),
+            }
+        except configparser.Error as err:
+            raise configparser.Error(
+                '{} in config file {}'.format(
+                    err.message, self.config_file
+                )
+            ) from err
+        else:
+            try:
+                wrapper = Etcd3Wrapper(*args, **kwargs)
+            except Exception as err:
+                logger.error(
+                    'etcd connection not successfull. Please check your config file.'
+                    '\nDetails: %s\netcd connection parameters: %s',
+                    err,
+                    kwargs,
+                )
+                sys.exit(1)
+            else:
+                return wrapper
+
+    def read_internal_values(self):
+        self.config_parser.read_dict(
+            {
+                'etcd': {
+                    'file_prefix': '/files/',
+                    'host_prefix': '/hosts/',
+                    'image_prefix': '/images/',
+                    'image_store_prefix': '/imagestore/',
+                    'network_prefix': '/networks/',
+                    'request_prefix': '/requests/',
+                    'user_prefix': '/users/',
+                    'vm_prefix': '/vms/',
+                }
+            }
+        )
+
+    def read_config_file_values(self, config_file):
+        try:
+            # Trying to read configuration file
+            with open(config_file, 'r') as config_file_handle:
+                self.config_parser.read_file(config_file_handle)
+        except FileNotFoundError:
+            sys.exit(
+                'Configuration file {} not found!'.format(config_file)
+            )
+        except Exception as err:
+            logger.exception(err)
+            sys.exit('Error occurred while reading configuration file')
+
+    def read_values_from_etcd(self):
+        etcd_client = self.get_etcd_client()
+        if (datetime.utcnow() - self.last_config_update).total_seconds() > 60:
+            config_from_etcd = etcd_client.get(self.config_key, value_in_json=True)
+            if config_from_etcd:
+                self.config_parser.read_dict(config_from_etcd.value)
+                self.last_config_update = datetime.utcnow()
+            else:
+                raise KeyError('Key \'{}\' not found in etcd. Please configure uncloud.'.format(self.config_key))
+
+    def __getitem__(self, key):
+        # Allow failing to read from etcd if we have
+        # it locally
+        if key not in self.config_parser.sections():
+            try:
+                self.read_values_from_etcd()
+            except KeyError:
+                pass
+
+        return self.config_parser[key]
+
+
+settings = Settings()