Source code for accre.database.engine

"""
SQLAclhemy engine object for connecting to the
ACCRE database
"""
import ssl

from sqlalchemy import create_engine

from accre.config import get_config


CONFIG = get_config()

_default_engine = None


def create_admin_engine():
    """
    Return an sqlalchemy Engine object to connect to the ACCRE admin
    database.
    :returns: Engine for the ACCRE admin database
    :rtype: sqlalchemy.engine.Engine
    """
    ssl_context = None
    cafile= CONFIG['admin-db'].get('cacert', '/accre/ca/ca.vampire.crt')
    if CONFIG['admin-db'].get('ssl', 'true').lower() == 'true':
        ssl_context = ssl.SSLContext()
        ssl_context.load_verify_locations(cafile=cafile)

    conn_str = '{0}://{1}:{2}@{3}:{4}/{5}'.format(
        CONFIG['admin-db']['driver'],
        CONFIG['admin-db']['user'],
        CONFIG['admin-db']['password'],
        CONFIG['admin-db']['host'],
        CONFIG['admin-db']['port'],
        CONFIG['admin-db']['database']
    )
    return create_engine(conn_str, connect_args={'ssl_context': ssl_context})


def get_default_engine():
    """
    The SQLAlchemy engine should generally persist over the application
    lifetime and can be safely reused between client objects. This
    helper function provides the admin engine if it has already been
    instantiated or creates it if not.
    """
    global _default_engine
    if _default_engine is None:
        _default_engine = create_admin_engine()
    return _default_engine


def set_default_engine(engine):
    """
    There is need to set a default engine in case an engine has already been registered
    from a different context. For example: during testing: setup might create the db client using an engine,
    any other dbclient accesses after that must happen through the same engine
        Args:
            engine: database engine
        Returns:
            None
    """
    global _default_engine
    _default_engine = engine