opensearch-sdk-rs

Rust proof of concept for OpenSearch 3.x extensions that run as a separate process instead of an in-process plugin.

The current implementation focuses on the REST-first extension lifecycle:

• transport frame parsing and encoding
• TCP and transport handshakes
• extension initialization
• REST route registration
• REST request dispatch for a hello-world extension

The design is intentionally closer to opensearch-sdk-py than the larger Java SDK surface.

Development Setup

This project uses Nix for managing development dependencies (Rust and JDK for local OpenSearch work).

Prerequisites

• Nix package manager installed with flakes enabled

Getting Started

1. Enter the Nix development shell:

   nix develop

2. Build the project:

   cargo build

3. Run the server:

   cargo run

4. Run tests:

   cargo test

5. Run the live OpenSearch 3.x hello-world harness:

   ./scripts/live_hello.sh

   This builds the local ../OpenSearch no-jdk-linux-tar archive if needed, starts the Rust extension, initializes it through /_extensions/initialize, and verifies /_extensions/_hello-world-rs/hello.

6. Run the cargo-visible ignored integration test for the same flow:

   cargo test --test live_hello -- --ignored --nocapture

   Use OPENSEARCH_DIR=/path/to/OpenSearch if your local checkout is not at ../OpenSearch.

Using Just

This project includes a justfile for common development tasks:

just build    # Build the project (with formatting)
just test     # Run tests
just run      # Run the server
just live_hello  # Run the end-to-end OpenSearch 3.x hello-world harness
just test_live_hello  # Run the ignored cargo integration test for the live harness
just fmt      # Format code
just clippy   # Run clippy lints

Without Nix

If you prefer not to use Nix, ensure you have the following installed:

• Rust toolchain (rustc, cargo, rustfmt)
• JDK 17 (for running OpenSearch)
• just command runner (optional)

What Works

• internal:tcp/handshake
• internal:transport/handshake
• internal:discovery/extensions
• internal:extensions/restexecuteonextensiontaction
• outbound internal:discovery/registerrestactions
• outbound internal:discovery/enviornmentsettings

Current POC Route

The sample binary exposes one route:

GET /hello

When registered through OpenSearch with the included examples/hello/hello.json, that route is expected to be reachable through:

/_extensions/_hello-world-rs/hello

The sample server accepts optional runtime overrides for live harnessing:

• OPENSEARCH_SDK_RS_HOST
• OPENSEARCH_SDK_RS_PORT
• OPENSEARCH_SDK_RS_TRACE

References

1. https://opensearch.org/blog/introducing-extensions-for-opensearch
2. https://github.com/opensearch-project/opensearch-sdk-py
3. https://github.com/opensearch-project/opensearch-sdk-java