def get_redis_connection(hostname=None, port=None):
""" Get a connection to a Redis server. The priority is:
- look for an environment variable REDISTOGO_URL (Heroku), else
- look for an environment variable REDIS_HOST, else
- look for an EC2 hosted server offering the service 'redis', else
- use localhost, 127.0.0.1.
"""
host = (
hostname or
os.environ.get("REDIS_HOST") or
ec2.get_hostname("redis") or
"127.0.0.1"
)
port = port or os.environ.get("REDIS_PORT", 6379)
url = os.environ.get('REDISTOGO_URL', # Set when on Heroku.
'redis://{}:{}'.format(host, port))
log.info("Connecting to Redis server at {}".format(url))
server = redis.from_url(url)
# Add some utility function. These functions first
# serialize to/from JSON the given object, then call redis get/set.
def redis_jget(key):
value = server.get(key)
return json.loads(value) if value else None
server.jset = lambda key, obj: server.set(key, json.dumps(obj))
server.jget = redis_jget
return server
def get_cube_host(hostname=None):
"""Get the hostname for the Cube server. These are tried, in order:
- an environment variable CUBE_HOST;
- an EC2 hosted server offering the service 'cube';
- 127.0.0.1.
"""
return (
hostname or
os.environ.get("CUBE_HOST") or
ec2.get_hostname("cube") or
"127.0.0.1"
)
def get_server(hostname=None, port=None, username=None, password=None,
protocol=None):
"""Return a server instance.
The following heuristic is used to find the server:
- function arguments take precedence over all else,
- environment variable COUCHDB_HOST is used otherwise,
- use the service finder of cloudly.aws.ec2 to look up a couchdb
server if none was found so far,
- else use 127.0.0.1
"""
host = (
hostname or
os.environ.get("COUCHDB_HOST") or
ec2.get_hostname("couchdb") or
"127.0.0.1"
)
protocol = protocol or os.environ.get("COUCHDB_PROTOCOL", "http")
port = port or os.environ.get("COUCHDB_PORT",
443 if protocol == "https" else 5984)
username = username or os.environ.get("COUCHDB_USERNAME", None)
password = password or os.environ.get("COUCHDB_PASSWORD", None)
if username is not None and password is not None:
url = "{protocol}://{username}:{password}@{host}:{port}".format(
protocol=protocol,
host=host,
port=port,
username=username,
password=password,
)
log.info("{} port {}, authenticated".format(host, port))
else:
url = "{protocol}://{host}:{port}".format(
protocol=protocol,
host=host,
port=port,
)
log.info("{} port {}".format(host, port))
return couchdb.Server(url)
