Google Cloud Storage

The Google Cloud Storage origin reads objects stored in Google Cloud Storage. The objects must be fully written and reside in a single bucket. The object names must share a prefix pattern.

With the Google Cloud Storage origin, you define the bucket, prefix pattern, and optional common prefix. These properties determine the objects that the origin processes.

You also define the project and credentials provider to use to connect to Google Cloud Storage. The origin can retrieve credentials from the Google Application Default Credentials or from a Google Cloud service account credentials file.

After processing an object or upon encountering errors, the origin can keep, archive, or delete the object. When archiving, the origin can copy or move the object.

When the pipeline stops, the Google Cloud Storage origin notes where it stops reading. When the pipeline starts again, the origin continues processing from where it stopped by default. You can reset the origin to process all requested objects.

The origin can generate events for an event stream. For more information about dataflow triggers and the event framework, see Dataflow Triggers Overview.

Credentials

Before reading objects in Google Cloud Storage, the Google Cloud Storage origin must pass credentials to Google Cloud Storage. Configure the origin to retrieve the credentials from the Google Application Default Credentials or from a Google Cloud service account credentials file.

Default Credentials Provider

When configured to use the Google Application Default Credentials, the origin checks for the credentials file defined in the GOOGLE_APPLICATION_CREDENTIALS environment variable. If the environment variable doesn't exist and Data Collector is running on a virtual machine (VM) in Google Cloud Platform (GCP), the origin uses the built-in service account associated with the virtual machine instance.

For more information about the default credentials, see Google Application Default Credentials in the Google Developer documentation.

Complete the following steps to define the credentials file in the environment variable:

  1. Use the Google Cloud Platform Console or the gcloud command-line tool to create a Google service account and have your application use it for API access.
    For example, to use the command line tool, run the following commands:
    gcloud iam service-accounts create my-account
gcloud iam service-accounts keys create key.json --iam-account=my-account@my-project.iam.gserviceaccount.com
  2. Store the generated credentials file on the Data Collector machine.
  3. Add the GOOGLE_APPLICATION_CREDENTIALS environment variable to the appropriate file and point it to the credentials file.

    Modify environment variables using the method required by your installation type.

    Set the environment variable as follows:

    export GOOGLE_APPLICATION_CREDENTIALS="/var/lib/sdc-resources/keyfile.json"
  4. Restart Data Collector to enable the changes.
  5. On the Credentials tab for the stage, select Default Credentials Provider for the credentials provider.

Service Account Credentials (JSON)

When configured to use the Google Cloud service account credentials file, the origin checks for the file defined in the origin properties.

Complete the following steps to use the service account credentials file:
  1. Generate a service account credentials file in JSON format.

    Use the Google Cloud Platform Console or the gcloud command-line tool to generate and download the credentials file. For more information, see generating a service account credential in the Google Cloud Platform documentation.

  2. Store the generated credentials file on the Data Collector machine.

    As a best practice, store the file in the Data Collector resources directory, $SDC_RESOURCES.

  3. On the Credentials tab for the stage, select Service Account Credentials File for the credentials provider and enter the path to the credentials file.

Common Prefix, Prefix Pattern, and Wildcards

The Google Cloud Storage origin appends the common prefix to the prefix pattern to define the objects that the origin processes. You can specify an exact prefix pattern or you can use Ant-style path patterns to read multiple objects recursively.

Ant-style path patterns can include the following wildcards:
  • Question mark (?) to match a single character
  • Asterisk (*) to match zero or more characters
  • Double asterisks (**) to match zero or more directories
For example, to process all log files in US/East/MD/ and all nested prefixes, you can use the following common prefix and prefix pattern:
Common Prefix: US/East/MD/
Prefix Pattern: **/*.log
If the unnamed nested prefixes that you want to include appear earlier in the hierarchy, such as US/**/weblogs/, you can include the nested prefixes in the prefix pattern or define the entire hierarchy in the prefix pattern, as follows:
Common Prefix: US/
Prefix Pattern: **/weblogs/*.log

Common Prefix: 
Prefix Pattern: US/**/weblogs/*.log

Event Generation

The Google Cloud Storage origin can generate events when it completes processing all available data and the configured batch wait time has elapsed.

Google Cloud Storage events can be used in any logical way. For example:
  • With the Pipeline Finisher executor to stop the pipeline and transition the pipeline to a Finished state when the origin completes processing available data.

    When you restart a pipeline stopped by the Pipeline Finisher executor, the origin continues processing from the last-saved offset unless you reset the origin.

    For an example, see Case Study: Stop the Pipeline.

  • With a destination to store event information.

    For an example, see Case Study: Event Storage.

For more information about dataflow triggers and the event framework, see Dataflow Triggers Overview.

Event Records

Event records generated by the Google Cloud Storage origin have the following event-related record header attributes. Record header attributes are stored as String values:
Record Header Attribute Description
sdc.event.type Event type. Uses the following type:
  • no-more-data - Generated after the origin completes processing all available objects and the number of seconds configured for Batch Wait Time has elapsed.
sdc.event.version An integer that indicates the version of the event record type.
sdc.event.creation_timestamp Epoch timestamp when the stage created the event.

The Google Cloud Storage origin can generate the following event record:

no-more-data
The Google Cloud Storage origin generates a no-more-data event record when the origin completes processing all available records and the number of seconds configured for Batch Wait Time elapses without any new objects appearing to be processed.
No-more-data event records generated by the origin have the sdc.event.type set to no-more-data and include the following fields:
Event Record Field Description
record-count Number of records successfully generated since the pipeline started or since the last no-more-data event was created.
error-count Number of error records generated since the pipeline started or since the last no-more-data event was created.
file-count Number of objects that the origin attempted to process. Can include objects that were unable to be processed or were not fully processed.

Data Formats

The Google Cloud Storage origin processes data differently based on the data format. The origin processes the following types of data:
Avro
Generates a record for every Avro record. Includes a "precision" and "scale" field attribute for each Decimal field. For more information about field attributes, see Field Attributes.
The origin writes the Avro schema to an avroSchema record header attribute. For more information about record header attributes, see Record Header Attributes.
You can use one of the following methods to specify the location of the Avro schema definition:
  • Message/Data Includes Schema - Use the schema in the file.
  • In Pipeline Configuration - Use the schema that you provide in the stage configuration.
  • Confluent Schema Registry - Retrieve the schema from Confluent Schema Registry. The Confluent Schema Registry is a distributed storage layer for Avro schemas. You can configure the origin to look up the schema in the Confluent Schema Registry by the schema ID or subject specified in the stage configuration.
Using a schema in the stage configuration or retrieving a schema from the Confluent Schema Registry overrides any schema that might be included in the file and can improve performance.
The origin reads files compressed by Avro-supported compression codecs without requiring additional configuration. To enable the origin to read files compressed by other codecs, use the compression format property in the stage.
Delimited
Generates a record for each delimited line. You can use the following delimited format types:
  • Default CSV - File that includes comma-separated values. Ignores empty lines in the file.
  • RFC4180 CSV - Comma-separated file that strictly follows RFC4180 guidelines.
  • MS Excel CSV - Microsoft Excel comma-separated file.
  • MySQL CSV - MySQL comma-separated file.
  • PostgreSQL CSV - PostgreSQL comma-separated file.
  • PostgreSQL Text - PostgreSQL text file.
  • Tab-Separated Values - File that includes tab-separated values.
  • Custom - File that uses user-defined delimiter, escape, and quote characters.
You can use a list or list-map root field type for delimited data, optionally including the header information when available. For more information about the root field types, see Delimited Data Root Field Type.
When using a header line, you can allow processing records with additional columns. The additional columns are named using a custom prefix and integers in sequential increasing order, such as _extra_1, _extra_2. When you disallow additional columns when using a header line, records that include additional columns are sent to error.
You can also replace a string constant with null values.
When a record exceeds the user-defined maximum record length, the origin cannot continue processing data in the file. Records already processed from the file are passed to the pipeline. The behavior of the origin is then based on the error handling configured for the stage:
  • Discard - The origin continues processing with the next file, leaving the partially-processed file in the directory.
  • To Error - The origin continues processing with the next file. If a post-processing error directory is configured for the stage, the origin moves the partially-processed file to the error directory. Otherwise, it leaves the file in the directory.
  • Stop Pipeline - The origin stops the pipeline.
Excel
Generates a record for every row in the file. Can process .xls or .xlsx files.
You can specify whether files include a header row and whether to ignore the header row. A header row must be the first row of a file. Vertical header columns are not recognized.
JSON
Generates a record for each JSON object. You can process JSON files that include multiple JSON objects or a single JSON array.
When an object exceeds the maximum object length defined for the origin, the origin cannot continue processing data in the file. Records already processed from the file are passed to the pipeline. The behavior of the origin is then based on the error handling configured for the stage:
  • Discard - The origin continues processing with the next file, leaving the partially-processed file in the directory.
  • To Error - The origin continues processing with the next file. If a post-processing error directory is configured for the stage, the origin moves the partially-processed file to the error directory. Otherwise, it leaves the file in the directory.
  • Stop Pipeline - The origin stops the pipeline.
Log
Generates a record for every log line.
When a line exceeds the user-defined maximum line length, the origin truncates longer lines.
You can include the processed log line as a field in the record. If the log line is truncated, and you request the log line in the record, the origin includes the truncated line.
You can define the log format or type to be read.
Protobuf
Generates a record for every protobuf message.
Protobuf messages must match the specified message type and be described in the descriptor file.
When the data for a record exceeds 1 MB, the origin cannot continue processing data in the file. The origin handles the file based on file error handling properties and continues reading the next file.
For information about generating the descriptor file, see Protobuf Data Format Prerequisites.
SDC Record
Generates a record for every record. Use to process records generated by a Data Collector pipeline using the SDC Record data format.
For error records, the origin provides the original record as read from the origin in the original pipeline, as well as error information that you can use to correct the record.
When processing error records, the origin expects the error file names and contents as generated by the original pipeline.
Text
Generates a record for each line of text or for each section of text based on a custom delimiter.
When a line or section exceeds the maximum line length defined for the origin, the origin truncates it. The origin adds a boolean field named Truncated to indicate if the line was truncated.
For more information about processing text with a custom delimiter, see Text Data Format with Custom Delimiters.
Whole File
Streams whole files from the origin system to the destination system. You can specify a transfer rate or use all available resources to perform the transfer.
The origin uses checksums to verify the integrity of data transmission.
The origin generates two fields: one for a file reference and one for file information. For more information, see Whole File Data Format.

Configuring a Google Cloud Storage Origin

Configure a Google Cloud Storage origin to read data from objects in Google Cloud Storage.
  1. In the Properties panel, on the General tab, configure the following properties:
    General Property Description
    Name Stage name.
    Description Optional description.
    Produce Events Generates event records when events occur. Use for event handling.
    On Record Error Error record handling for the stage:
    • Discard - Discards the record.
    • Send to Error - Sends the record to the pipeline for error handling.
    • Stop Pipeline - Stops the pipeline.
  2. On the GCS tab, configure the following properties:
    GCS Property Description
    Bucket Bucket that contains the objects to be read.
    Note: The bucket name must be DNS compliant. For more information about bucket naming conventions, see the Google Cloud Storage documentation.

    For a full list of origins that support this data format, see Origins in the "Data Formats by Stage" appendix.

    For a full list of destinations that support this data format, see Destinations in the "Data Formats by Stage" appendix.

    For a list of origins and destinations that process this data format, see Data Format Support.
    Common Prefix Optional common prefix that describes the location of the objects. When defined, the common prefix acts as a root for the prefix pattern.
    Prefix Pattern Prefix pattern that describes the objects to be processed.

    You can include the entire path to the objects. You can also use Ant-style path patterns to read objects recursively.

    Max Batch Size (records) Maximum number of records processed at one time. Honors values up to the Data Collector maximum batch size.

    Default is 1000. The Data Collector default is 1000.
    Batch Wait Time (ms) Number of milliseconds to wait before sending a partial or empty batch.
  3. On the Error Handling tab, configure the following properties:
    Error Handling Property Description
    Error Handling Option The action taken when an error occurs while processing an object:
    • None - Keeps the object in place.
    • Archive - Copies or moves the object to another prefix or bucket.
    • Delete - Deletes the object.

    When archiving processed objects, best practice is to also archive objects that cannot be processed.

    Archiving Option The action to take when archiving an object that cannot be processed.

    You can copy or move the object to another prefix or bucket. When you use another prefix, enter the prefix. When you use another bucket, enter a prefix and bucket.

    Copying the object leaves the original object in place.

    Error Prefix Prefix for the objects that cannot be processed.
    Error Bucket Bucket for the objects that cannot be processed.
  4. On the Data Format tab, configure the following property:
    Data Format Property Description
    Data Format Data format for source files. Use one of the following formats:
    • Avro
    • Delimited
    • Excel
    • JSON
    • Log
    • Protobuf
    • SDC Record
    • Text
    • Whole File
  5. For Avro data, on the Data Format tab, configure the following properties:
    Avro Property Description
    Avro Schema Location Location of the Avro schema definition to use when processing data:
    • Message/Data Includes Schema - Use the schema in the file.
    • In Pipeline Configuration - Use the schema provided in the stage configuration.
    • Confluent Schema Registry - Retrieve the schema from the Confluent Schema Registry.

    Using a schema in the stage configuration or in the Confluent Schema Registry can improve performance.
    Avro Schema Avro schema definition used to process the data. Overrides any existing schema definitions associated with the data.

    You can optionally use the runtime:loadResource function to use a schema definition stored in a runtime resource file.

    Schema Registry URLs Confluent Schema Registry URLs used to look up the schema. To add a URL, click Add. Use the following format to enter the URL:
    http://<host name>:<port number>
    Lookup Schema By Method used to look up the schema in the Confluent Schema Registry:
    • Subject - Look up the specified Avro schema subject.
    • Schema ID - Look up the specified Avro schema ID.
    Overrides any existing schema definitions associated with the data.
    Schema Subject Avro schema subject to look up in the Confluent Schema Registry.

    If the specified subject has multiple schema versions, the origin uses the latest schema version for that subject. To use an older version, find the corresponding schema ID, and then set the Look Up Schema By property to Schema ID.
    Schema ID Avro schema ID to look up in the Confluent Schema Registry.
  6. For delimited data, on the Data Format tab, configure the following properties:
    Delimited Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
    Delimiter Format Type Delimiter format type. Use one of the following options:
    • Default CSV - File that includes comma-separated values. Ignores empty lines in the file.
    • RFC4180 CSV - Comma-separated file that strictly follows RFC4180 guidelines.
    • MS Excel CSV - Microsoft Excel comma-separated file.
    • MySQL CSV - MySQL comma-separated file.
    • PostgreSQL CSV - PostgreSQL comma-separated file.
    • PostgreSQL Text - PostgreSQL text file.
    • Tab-Separated Values - File that includes tab-separated values.
    • Custom - File that uses user-defined delimiter, escape, and quote characters.
    Header Line Indicates whether a file contains a header line, and whether to use the header line.
    Allow Extra Columns When processing data with a header line, allows processing records with more columns than exist in the header line.
    Extra Column Prefix Prefix to use for any additional columns. Extra columns are named using the prefix and sequential increasing integers as follows: <prefix><integer>.

    For example, _extra_1. Default is _extra_.
    Max Record Length (chars) Maximum length of a record in characters. Longer records are not read.

    This property can be limited by the Data Collector parser buffer size. For more information, see Maximum Record Size.
    Delimiter Character Delimiter character for a custom delimiter format. Select one of the available options or use Other to enter a custom character.

    You can enter a Unicode control character using the format \uNNNN, where ​N is a hexadecimal digit from the numbers 0-9 or the letters A-F. For example, enter \u0000 to use the null character as the delimiter or \u2028 to use a line separator as the delimiter.

    Default is the pipe character ( | ).
    Escape Character Escape character for a custom file type.
    Quote Character Quote character for a custom file type.
    Root Field Type Root field type to use:
    • List-Map - Generates an indexed list of data. Enables you to use standard functions to process data. Use for new pipelines.
    • List - Generates a record with an indexed list with a map for header and value. Requires the use of delimited data functions to process data. Use only to maintain pipelines created before 1.1.0.
    Lines to Skip Lines to skip before reading data.
    Parse NULLs Replaces the specified string constant with null values.
    NULL Constant String constant to replace with null values.
    Charset Character encoding of the files to be processed.
    Ignore Ctrl Characters Removes all ASCII control characters except for the tab, line feed, and carriage return characters.
  7. For Excel files, on the Data Format tab, configure the following property:
    Excel Property Description
    Excel Header Option Indicates whether files include a header row and whether to ignore the header row. A header row must be the first row of a file.
  8. For JSON data, on the Data Format tab, configure the following properties:
    JSON Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
    JSON Content Type of JSON content. Use one of the following options:
    • Array of Objects
    • Multiple Objects
    Maximum Object Length (chars) Maximum number of characters in a JSON object.

    Longer objects are diverted to the pipeline for error handling.

    This property can be limited by the Data Collector parser buffer size. For more information, see Maximum Record Size.
    Charset Character encoding of the files to be processed.
    Ignore Ctrl Characters Removes all ASCII control characters except for the tab, line feed, and carriage return characters.
  9. For log data, on the Data Format tab, configure the following properties:
    Log Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
    Log Format Format of the log files. Use one of the following options:
    • Common Log Format
    • Combined Log Format
    • Apache Error Log Format
    • Apache Access Log Custom Format
    • Regular Expression
    • Grok Pattern
    • Log4j
    • Common Event Format (CEF)
    • Log Event Extended Format (LEEF)
    Max Line Length Maximum length of a log line. The origin truncates longer lines.

    This property can be limited by the Data Collector parser buffer size. For more information, see Maximum Record Size.
    Retain Original Line Determines how to treat the original log line. Select to include the original log line as a field in the resulting record.

    By default, the original line is discarded.
    Charset Character encoding of the files to be processed.
    Ignore Ctrl Characters Removes all ASCII control characters except for the tab, line feed, and carriage return characters.
    • When you select Apache Access Log Custom Format, use Apache log format strings to define the Custom Log Format.
    • When you select Regular Expression, enter the regular expression that describes the log format, and then map the fields that you want to include to each regular expression group.
    • When you select Grok Pattern, you can use the Grok Pattern Definition field to define custom grok patterns. You can define a pattern on each line.

      In the Grok Pattern field, enter the pattern to use to parse the log. You can use a predefined grok patterns or create a custom grok pattern using patterns defined in Grok Pattern Definition.

      For more information about defining grok patterns and supported grok patterns, see Defining Grok Patterns.

    • When you select Log4j, define the following properties:
      Log4j Property Description
      On Parse Error Determines how to handle information that cannot be parsed:
      • Skip and Log Error - Skips reading the line and logs a stage error.
      • Skip, No Error - Skips reading the line and does not log an error.
      • Include as Stack Trace - Includes information that cannot be parsed as a stack trace to the previously-read log line. The information is added to the message field for the last valid log line.
      Use Custom Log Format Allows you to define a custom log format.
      Custom Format Use log4j variables to define a custom log format.
  10. For protobuf data, on the Data Format tab, configure the following properties:
    Protobuf Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
    Protobuf Descriptor File Descriptor file (.desc) to use. The descriptor file must be in the Data Collector resources directory, $SDC_RESOURCES.

    For more information about environment variables, see Data Collector Environment Configuration. For information about generating the descriptor file, see Protobuf Data Format Prerequisites.
    Message Type The fully-qualified name for the message type to use when reading data.

    Use the following format: <package name>.<message type>.

    Use a message type defined in the descriptor file.
    Delimited Messages Indicates if a file might include more than one protobuf message.
  11. For SDC Record data, on the Data Format tab, configure the following properties:
    SDC Record Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
  12. For text data, on the Data Format tab, configure the following properties:
    Text Property Description
    Compression Format The compression format of the files:
    • None - Processes only uncompressed files.
    • Compressed File - Processes files compressed by the supported compression formats.
    • Archive - Processes files archived by the supported archive formats.
    • Compressed Archive - Processes files archived and compressed by the supported archive and compression formats.
    File Name Pattern within Compressed Directory For archive and compressed archive files, file name pattern that represents the files to process within the compressed directory. You can use UNIX-style wildcards, such as an asterisk or question mark. For example, *.json.

    Default is *, which processes all files.
    Max Line Length Maximum number of characters allowed for a line. Longer lines are truncated.

    Adds a boolean field to the record to indicate if it was truncated. The field name is Truncated.

    This property can be limited by the Data Collector parser buffer size. For more information, see Maximum Record Size.
    Use Custom Delimiter Uses custom delimiters to define records instead of line breaks.
    Custom Delimiter One or more characters to use to define records.
    Include Custom Delimiter Includes delimiter characters in the record.
    Charset Character encoding of the files to be processed.
    Ignore Ctrl Characters Removes all ASCII control characters except for the tab, line feed, and carriage return characters.
  13. For whole files, on the Data Format tab, configure the following properties:
    Whole File Property Description
    Buffer Size (bytes) Size of the buffer to use to transfer data.
    Rate per Second Transfer rate to use.

    Enter a number to specify a rate in bytes per second. Use an expression to specify a rate that uses a different unit of measure per second, e.g. ${5 * MB}. Use -1 to opt out of this property.

    By default, the origin does not use a transfer rate.

    Verify Checksum Verifies the checksum during the read.
  14. On the Credentials tab, configure the following properties:
    Credentials Property Description
    Project ID Google Cloud Storage project ID to connect to.
    Credentials Provider Credentials provider to use to connect to Google Cloud Storage:
    • Default credentials provider
    • Service account credentials file (JSON)
    Credentials File Path (JSON) When using a Google Cloud service account credentials file, path to the file that the origin uses to connect to Google Cloud Storage. The credentials file must be a JSON file.

    Enter a path relative to the Data Collector resources directory, $SDC_RESOURCES, or enter an absolute path.