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from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils.decorators import apply_defaults
[docs]class S3PrefixSensor(BaseSensorOperator):
"""
Waits for a prefix to exist. A prefix is the first part of a key,
thus enabling checking of constructs similar to glob airfl* or
SQL LIKE 'airfl%'. There is the possibility to precise a delimiter to
indicate the hierarchy or keys, meaning that the match will stop at that
delimiter. Current code accepts sane delimiters, i.e. characters that
are NOT special characters in the Python regex engine.
:param bucket_name: Name of the S3 bucket
:type bucket_name: str
:param prefix: The prefix being waited on. Relative path from bucket root level.
:type prefix: str
:param delimiter: The delimiter intended to show hierarchy.
Defaults to '/'.
:type delimiter: str
:param aws_conn_id: a reference to the s3 connection
:type aws_conn_id: str
"""
template_fields = ('prefix', 'bucket_name')
@apply_defaults
def __init__(self,
bucket_name,
prefix,
delimiter='/',
aws_conn_id='aws_default',
*args,
**kwargs):
super(S3PrefixSensor, self).__init__(*args, **kwargs)
# Parse
self.bucket_name = bucket_name
self.prefix = prefix
self.delimiter = delimiter
self.full_url = "s3://" + bucket_name + '/' + prefix
self.aws_conn_id = aws_conn_id
[docs] def poke(self, context):
self.log.info('Poking for prefix : {self.prefix}\n'
'in bucket s3://{self.bucket_name}'.format(**locals()))
from airflow.hooks.S3_hook import S3Hook
hook = S3Hook(aws_conn_id=self.aws_conn_id)
return hook.check_for_prefix(
prefix=self.prefix,
delimiter=self.delimiter,
bucket_name=self.bucket_name)