zstd

Zstandard response compression for the RoadRunner HTTP plugin. The implementation uses klauspost/compress/gzhttp and does not require CGO.

Usage

Include github.com/roadrunner-server/zstd/v6 in your RoadRunner build. Register &zstd.Plugin{} with Endure alongside the HTTP and server plugins. Configuration alone cannot load a plugin that is absent from the build.

Add zstd to the middleware list in your HTTP configuration:

http:
  middleware: ["zstd"]

The plugin does not require a separate configuration section. A client requests compression with Accept-Encoding: zstd. Eligible responses use Content-Encoding: zstd.

Behavior

• Only zstd response compression is enabled. The plugin does not provide gzip fallback or request-body decompression.
• Clients must request zstd explicitly with a nonzero quality value. Missing or unsupported encodings and zstd;q=0 leave the response uncompressed.
• The default compression level is zstd.SpeedFastest. Encoders are pooled.
• The normal minimum response size is 1,024 bytes. A flush can start compression below this limit.
• The wrapper skips HEAD requests, empty bodies, existing Content-Encoding, Content-Range, and content types excluded by the library.
• The wrapper adds Vary: Accept-Encoding. It removes the original Content-Length when it compresses a response.
• HTTP behavior follows the same library as the gzip plugin. The wrapper does not change ETags by default.
• Tracing follows the RoadRunner middleware convention when the request contains the RoadRunner tracer context key.

If both gzip and zstd middleware are enabled, their order can determine the selected encoding. The separate plugins do not compare quality values with each other.

Tests

Run the unit tests and static checks from the repository root:

go test -race -tags=debug ./...
go vet ./...

The integration tests use a separate Go module and a real PHP worker. They require Composer and PHP with the extensions required by the worker packages, including sockets. The worker uses the php executable from PATH.

composer --working-dir=tests/php_test_files install
go -C tests test -race -tags=debug ./...
go -C tests vet ./...

The integration tests register the plugin through Endure and select it through http.middleware. They check the encoded response and decode it with zstd. They also check unsupported clients and a registered plugin that is not selected in the middleware list.