ListGCSBucket

Description:

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.

Additional Details...

Tags:

google cloud, google, storage, gcs, list

Properties:

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, whether a property supports the NiFi Expression Language, and whether a property is considered "sensitive", meaning that its value will be encrypted. Before entering a value in a sensitive property, ensure that the nifi.properties file has an entry for the property nifi.sensitive.props.key.

NameDefault ValueAllowable ValuesDescription
Listing StrategyTracking Timestamps
  • Tracking Timestamps This strategy tracks the latest timestamp of listed entity to determine new/updated entities. Since it only tracks few timestamps, it can manage listing state efficiently. This strategy will not pick up any newly added or modified entity if their timestamps are older than the tracked latest timestamp. Also may miss files when multiple subdirectories are being written at the same time while listing is running.
  • Tracking Entities This strategy tracks information of all the listed entities within the latest 'Entity Tracking Time Window' to determine new/updated entities. This strategy can pick entities having old timestamp that can be missed with 'Tracing Timestamps'. Works even when multiple subdirectories are being written at the same time while listing is running. However an additional DistributedMapCache controller service is required and more JVM heap memory is used. For more information on how the 'Entity Tracking Time Window' property works, see the description.
Specify how to determine new/updated entities. See each strategy descriptions for detail.
Entity Tracking State CacheController Service API:
DistributedMapCacheClient
Implementations: HBase_1_1_2_ClientMapCacheService
RedisDistributedMapCacheClientService
CouchbaseMapCacheClient
CassandraDistributedMapCache
HazelcastMapCacheClient
DistributedMapCacheClientService
HBase_2_ClientMapCacheService
Listed entities are stored in the specified cache storage so that this processor can resume listing across NiFi restart or in case of primary node change. 'Tracking Entities' strategy require tracking information of all listed entities within the last 'Tracking Time Window'. To support large number of entities, the strategy uses DistributedMapCache instead of managed state. Cache key format is 'ListedEntities::{processorId}(::{nodeId})'. If it tracks per node listed entities, then the optional '::{nodeId}' part is added to manage state separately. E.g. cluster wide cache key = 'ListedEntities::8dda2321-0164-1000-50fa-3042fe7d6a7b', per node cache key = 'ListedEntities::8dda2321-0164-1000-50fa-3042fe7d6a7b::nifi-node3' The stored cache content is Gzipped JSON string. The cache key will be deleted when target listing configuration is changed. Used by 'Tracking Entities' strategy.

This Property is only considered if the [Listing Strategy] Property has a value of "Tracking Entities".
Entity Tracking Initial Listing TargetAll Available
  • Tracking Time Window Ignore entities having timestamp older than the specified 'Tracking Time Window' at the initial listing activity.
  • All Available Regardless of entities timestamp, all existing entities will be listed at the initial listing activity.
Specify how initial listing should be handled. Used by 'Tracking Entities' strategy.

This Property is only considered if the [Listing Strategy] Property has a value of "Tracking Entities".
Entity Tracking Time Window3 hoursSpecify how long this processor should track already-listed entities. 'Tracking Entities' strategy can pick any entity whose timestamp is inside the specified time window. For example, if set to '30 minutes', any entity having timestamp in recent 30 minutes will be the listing target when this processor runs. A listed entity is considered 'new/updated' and a FlowFile is emitted if one of following condition meets: 1. does not exist in the already-listed entities, 2. has newer timestamp than the cached entity, 3. has different size than the cached entity. If a cached entity's timestamp becomes older than specified time window, that entity will be removed from the cached already-listed entities. Used by 'Tracking Entities' strategy.
Supports Expression Language: true (will be evaluated using variable registry only)

This Property is only considered if the [Entity Tracking Initial Listing Target] Property has a value of "Tracking Time Window".
BucketBucket of the object.
Supports Expression Language: true (will be evaluated using variable registry only)
Record WriterController Service API:
RecordSetWriterFactory
Implementations: RecordSetWriterLookup
AvroRecordSetWriter
FreeFormTextRecordSetWriter
XMLRecordSetWriter
ScriptedRecordSetWriter
CSVRecordSetWriter
JsonRecordSetWriter
ParquetRecordSetWriter
Specifies the Record Writer to use for creating the listing. If not specified, one FlowFile will be created for each entity that is listed. If the Record Writer is specified, all entities will be written to a single FlowFile instead of adding attributes to individual FlowFiles.
Project IDGoogle Cloud Project ID
Supports Expression Language: true (will be evaluated using variable registry only)
GCP Credentials Provider ServiceController Service API:
GCPCredentialsService
Implementation: GCPCredentialsControllerService
The Controller Service used to obtain Google Cloud Platform credentials.
Number of retries6How many retry attempts should be made before routing to the failure relationship.
Proxy hostIP or hostname of the proxy to be used. You might need to set the following properties in bootstrap for https proxy usage: -Djdk.http.auth.tunneling.disabledSchemes= -Djdk.http.auth.proxying.disabledSchemes=
Supports Expression Language: true (will be evaluated using variable registry only)
Proxy portProxy port number
Supports Expression Language: true (will be evaluated using variable registry only)
HTTP Proxy UsernameHTTP Proxy Username
Supports Expression Language: true (will be evaluated using variable registry only)
HTTP Proxy PasswordHTTP Proxy Password
Sensitive Property: true
Supports Expression Language: true (will be evaluated using variable registry only)
Proxy Configuration ServiceController Service API:
ProxyConfigurationService
Implementation: StandardProxyConfigurationService
Specifies the Proxy Configuration Controller Service to proxy network requests. If set, it supersedes proxy settings configured per component. Supported proxies: HTTP + AuthN
PrefixThe prefix used to filter the object list. In most cases, it should end with a forward slash ('/').
Supports Expression Language: true (will be evaluated using variable registry only)
Use Generationsfalse
  • true
  • false
Specifies whether to use GCS Generations, if applicable. If false, only the latest version of each object will be returned.

Relationships:

NameDescription
successFlowFiles are routed to this relationship after a successful Google Cloud Storage operation.

Reads Attributes:

None specified.

Writes Attributes:

NameDescription
filenameThe name of the file
gcs.bucketBucket of the object.
gcs.keyName of the object.
gcs.sizeSize of the object.
gcs.cache.controlData cache control of the object.
gcs.component.countThe number of components which make up the object.
gcs.content.dispositionThe data content disposition of the object.
gcs.content.encodingThe content encoding of the object.
gcs.content.languageThe content language of the object.
mime.typeThe MIME/Content-Type of the object
gcs.crc32cThe CRC32C checksum of object's data, encoded in base64 in big-endian order.
gcs.create.timeThe creation time of the object (milliseconds)
gcs.update.timeThe last modification time of the object (milliseconds)
gcs.encryption.algorithmThe algorithm used to encrypt the object.
gcs.encryption.sha256The SHA256 hash of the key used to encrypt the object
gcs.etagThe HTTP 1.1 Entity tag for the object.
gcs.generated.idThe service-generated for the object
gcs.generationThe data generation of the object.
gcs.md5The MD5 hash of the object's data encoded in base64.
gcs.media.linkThe media download link to the object.
gcs.metagenerationThe metageneration of the object.
gcs.ownerThe owner (uploader) of the object.
gcs.owner.typeThe ACL entity type of the uploader of the object.
gcs.uriThe URI of the object as a string.

State management:

ScopeDescription
CLUSTERAfter 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.

Restricted:

This component is not restricted.

Input requirement:

This component does not allow an incoming relationship.

System Resource Considerations:

None specified.

See Also:

PutGCSObject, DeleteGCSObject, FetchGCSObject