grpcserver

grpcserver

gRPC server interceptors for LabKit v2. The gRPC counterpart to httpserver.

Correlation IDs

UnaryServerCorrelationInterceptor and StreamServerCorrelationInterceptor resolve a correlation ID for every incoming call and make it available to the handler via correlation.ExtractFromContext:

srv := grpc.NewServer(
	grpc.ChainUnaryInterceptor(grpcserver.UnaryServerCorrelationInterceptor()),
	grpc.ChainStreamInterceptor(grpcserver.StreamServerCorrelationInterceptor()),
)

Chain them outermost so every later interceptor and the handler observe the ID.

Behaviour, mirroring httpserver.CorrelationIDMiddleware:

• Reads x-gitlab-correlation-id from incoming metadata (CorrelationIDHeader). This is LabKit v1's gRPC header, so v1 clients propagate into v2 servers unchanged. Metadata keys are case-insensitive.
• Validates the value with correlation.Sanitize: trimmed, non-empty, at most correlation.MaxIDLen (255) characters, only [a-zA-Z0-9_-]. Anything else is replaced with a freshly generated UUID, which prevents log injection and downstream poisoning from caller-supplied values.
• Echoes the resolved ID back to the client as a response header under the same key.

Note: v1's correlation/grpc interceptors accepted the incoming value verbatim. Services migrating from v1 gain validation; callers sending IDs outside the allowed character set will see them replaced. Generated IDs are UUIDs (as on v2's HTTP path), not v1's ULIDs.

Do not mix with v1: v1 and v2 store the ID under different context keys, so an ID injected here is invisible to v1's correlation and log packages and correlation_id silently disappears from v1 access logs. Migrate the correlation interceptor and the access logger together.