databuild/databuild

DataBuild Protobuf Interfaces

This directory contains the protobuf interfaces for DataBuild, implemented as a hermetic Bazel-native solution.

Architecture

Hermetic Build Approach

Instead of relying on external Cargo dependencies or complex protoc toolchains, we use a hermetic Bazel genrule that generates Rust code directly from the protobuf specification. This ensures:

• Full Hermeticity: No external dependencies beyond what's in the Bazel workspace
• Consistency: Same generated code across all environments
• Performance: Fast builds without complex dependency resolution
• Simplicity: Pure Bazel solution that integrates seamlessly

Generated Code Structure

The build generates Rust structs that mirror the protobuf specification in databuild.proto:

// Core types
pub struct PartitionRef { pub str: String }
pub struct JobConfig { /* ... */ }
pub struct JobGraph { /* ... */ }
// ... and all other protobuf messages

Custom Serialization

Since we're hermetic, we implement our own JSON serialization instead of relying on serde:

let partition = PartitionRef::new("my-partition");
let json = partition.to_json(); // {"str":"my-partition"}
let parsed = PartitionRef::from_json(&json).unwrap();

Usage

In BUILD.bazel files:

rust_library(
    name = "my_service",
    deps = ["//databuild:databuild"],
    # ... 
)

In Rust code:

use databuild::*;

let partition = PartitionRef::new("my-partition");
let job_config = JobConfig {
    outputs: vec![partition],
    inputs: vec![],
    args: vec!["process".to_string()],
    env: HashMap::new(),
};

Build Targets

• //databuild:databuild - Main library with generated protobuf types
• //databuild:databuild_test - Tests for the generated code
• //databuild:databuild_proto - The protobuf library definition
• //databuild:structs - Legacy manually-written structs (deprecated)

Testing

bazel test //databuild:...

Benefits of This Approach

1. No External Dependencies: Eliminates prost, tonic-build, and complex protoc setups
2. Bazel Native: Fully integrated with Bazel's dependency graph
3. Fast Builds: No compilation of external crates or complex build scripts
4. Hermetic: Same results every time, everywhere
5. Maintainable: Simple genrule that's easy to understand and modify
6. Extensible: Easy to add custom methods and serialization logic

Future Enhancements

• Add wire-format serialization if needed
• Generate service stubs for gRPC-like communication
• Add validation methods for message types
• Extend custom serialization to support more formats