Retrieves a listing of objects from an GCS bucket. For each object that is listed, creates a FlowFile that represents the object so that it can be fetched in conjunction with FetchGCSObject. This Processor is designed to run on Primary Node only in a cluster. If the primary node changes, the new Primary Node will pick up where the previous node left off without duplicating all of the data.


google cloud, google, storage, gcs, list


In the list below, the names of required properties appear in bold. Any other properties (not in bold) are considered optional. The table also indicates any default values.

Name Default Value Allowable Values Description
GCP Credentials Provider Service Controller Service API:
The Controller Service used to obtain Google Cloud Platform credentials.
Project ID Google Cloud Project ID
Number of retries 6 How many retry attempts should be made before routing to the failure relationship.
Bucket Bucket of the object.
Prefix The prefix used to filter the object list. In most cases, it should end with a forward slash ('/').
Use Generations false * true
* false
Specifies whether to use GCS Generations, if applicable. If false, only the latest version of each object will be returned.


Name Description
success FlowFiles are routed to this relationship after a successful Google Cloud Storage operation.

Reads Attributes:

None specified.

Writes Attributes:

Name Description
filename The name of the file
gcs.bucket Bucket of the object.
gcs.key Name of the object.
gcs.size Size of the object.
gcs.cache.control Data cache control of the object.
gcs.component.count The number of components which make up the object.
gcs.content.disposition The data content disposition of the object.
gcs.content.encoding The content encoding of the object.
gcs.content.language The content language of the object.
mime.type The MIME/Content-Type of the object
gcs.crc32c The CRC32C checksum of object's data, encoded in base64 in big-endian order.
gcs.create.time The creation time of the object (milliseconds)
gcs.update.time The last modification time of the object (milliseconds)
gcs.encryption.algorithm The algorithm used to encrypt the object.
gcs.encryption.sha256 The SHA256 hash of the key used to encrypt the object
gcs.etag The HTTP 1.1 Entity tag for the object. The service-generated for the object
gcs.generation The data generation of the object.
gcs.md5 The MD5 hash of the object's data encoded in base64. The media download link to the object.
gcs.metageneration The metageneration of the object.
gcs.owner The owner (uploader) of the object.
gcs.owner.type The ACL entity type of the uploader of the object.
gcs.uri The URI of the object as a string.

State management:

Scope Description
CLUSTER After performing a listing of keys, the timestamp of the newest key is stored, along with the keys that share that same timestamp. This allows the Processor to list only keys that have been added or modified after this date the next time that the Processor is run. State is stored across the cluster so that this Processor can be run on Primary Node only and if a new Primary Node is selected, the new node can pick up where the previous node left off, without duplicating the data.


This component is not restricted.

Input requirement:

This component does not allow an incoming relationship.

See Also:

PutGCSObject, DeleteGCSObject, FetchGCSObject