feat: add Bigtable Change Streams to Bigtable template and support Bigtable output in Streaming Data Generator

[stankiewicz]

Changes:

1. Streaming Data Generator: Native BigTableIO Sink

• Introduced new sink transform StreamingDataGeneratorWriteToBigtable to map incoming JSON messages directly into PCollection<KV<ByteString, Iterable<Mutation>>> into BigtableIO.write().

2. New Template: Bigtable Change Streams to Bigtable Replicator

• Implemented a streaming pipeline BigtableChangeStreamsToBigtable.java under v2/googlecloud-to-googlecloud that ingests CDC mutations and replicates them to another Cloud Bigtable instance. Kind of similar to BigTableToHBase.

3. Documentation & Infrastructure Automation

• Auto-Generated Markdown READMEs: README_Bigtable_Change_Streams_to_Bigtable.md, README_Streaming_Data_Generator.md
• Terraform Provisioning: Generated Terraform

Verification Results:

• spotless, checkstyle, unit tests
• Executed IT tests on personal project.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new streaming pipeline template for replicating Bigtable change stream mutations between instances, alongside a new native Bigtable sink for the Streaming Data Generator. These additions expand the capabilities of the Dataflow templates library by providing robust CDC replication and improved data generation testing support for Bigtable.

Highlights

• Bigtable Change Streams to Bigtable Template: Added a new streaming pipeline template to replicate Bigtable change stream mutations to another Bigtable instance, supporting features like bidirectional replication and mutation filtering.
• Streaming Data Generator Sink: Introduced a native Bigtable sink to the Streaming Data Generator, enabling direct writing of generated JSON messages to Bigtable tables.
• Documentation and Infrastructure: Included auto-generated README files and Terraform provisioning scripts for the new template, and updated existing documentation for the Streaming Data Generator.

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[gemini-code-assist]

Code Review

This pull request introduces a new Dataflow template, "Bigtable Change Streams to Bigtable Replicator," which facilitates the replication of Bigtable change stream mutations between instances, including support for bidirectional replication and garbage collection filtering. It also adds a Bigtable sink to the "Streaming Data Generator" template. Review feedback suggests enhancing the Bigtable write configuration to expose performance-tuning parameters, optimizing JSON parsing by reading directly from byte arrays to avoid unnecessary string allocations, and using more idiomatic Jackson API methods for iterating over JSON fields.

[codecov]

Codecov Report

❌ Patch coverage is 51.82482% with 132 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.51%. Comparing base (00cd31f) to head (632801e).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...amstobigtable/BigtableChangeStreamsToBigtable.java	47.05%	84 Missing and 15 partials ⚠️
...nsforms/StreamingDataGeneratorWriteToBigtable.java	57.35%	25 Missing and 4 partials ⚠️
.../teleport/v2/templates/StreamingDataGenerator.java	78.94%	0 Missing and 4 partials ⚠️

❌ Your patch check has failed because the patch coverage (51.82%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3774      +/-   ##
============================================
+ Coverage     53.29%   53.51%   +0.21%     
+ Complexity     6575     6231     -344     
============================================
  Files          1079     1084       +5     
  Lines         65576    66141     +565     
  Branches       7301     7382      +81     
============================================
+ Hits          34948    35393     +445     
- Misses        28277    28366      +89     
- Partials       2351     2382      +31     

Components	Coverage Δ
spanner-templates	72.83% <ø> (+0.04%)	⬆️
spanner-import-export	68.65% <ø> (+0.12%)	⬆️
spanner-live-forward-migration	80.93% <ø> (-0.02%)	⬇️
spanner-live-reverse-replication	77.08% <ø> (+0.01%)	⬆️
spanner-bulk-migration	91.10% <ø> (-0.01%)	⬇️
gcs-spanner-dv	85.74% <ø> (-0.02%)	⬇️

Files with missing lines	Coverage Δ
.../teleport/v2/templates/StreamingDataGenerator.java	39.86% <78.94%> (+5.24%)	⬆️
...nsforms/StreamingDataGeneratorWriteToBigtable.java	57.35% <57.35%> (ø)
...amstobigtable/BigtableChangeStreamsToBigtable.java	47.05% <47.05%> (ø)

... and 24 files with indirect coverage changes

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