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interceptors.go
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interceptors.go
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package requestid
import (
"context"
grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
"github.com/renstrom/shortuuid"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
// MetadataKey is the HTTP header key using this key we use to store request ids.
// This is the standard key used for request Ids. For example, opentelemetry uses the same one.
const MetadataKey = "x-request-id"
// FromContext returns the request Id embedded in gRPC metadata stored in a context,
// if one is available. The second return value is true if the operation was successful.
func FromContext(ctx context.Context) (string, bool) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
return "", false
}
ids, ok := md[MetadataKey]
if !ok || len(ids) == 0 {
return "", false
}
return ids[0], true
}
// FromContextOrMissing returns the request Id embedded in gRPC metadata stored in a context,
// if one is available. If none is available, the string "missing" is returned.
func FromContextOrMissing(ctx context.Context) string {
if id, ok := FromContext(ctx); ok {
return id
}
return "missing"
}
// AddToIncomingContext returns a new context derived from ctx that is annotated with an Id.
// The Id is stored in the request gRPC metadata. If ctx already has an Id, it is overwritten.
// The second return value is true if the operation was successful.
func AddToIncomingContext(ctx context.Context, id string) (context.Context, bool) {
if md, ok := metadata.FromIncomingContext(ctx); ok {
md.Set(MetadataKey, id)
return metadata.NewIncomingContext(ctx, md), true
}
return ctx, false
}
// UnaryServerInterceptor returns an interceptor that annotates incoming gRPC requests with an Id.
// Ids are stored in the gRPC request metadata and are generated using github.com/renstrom/shortuuid.
// If replace is false, this is only done for requests that do not already have an Id.
func UnaryServerInterceptor(replace bool) grpc.UnaryServerInterceptor {
return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
if _, ok := FromContext(ctx); !ok || replace {
id := shortuuid.New()
ctx, _ = AddToIncomingContext(ctx, id) // If the operation fails, the original context is returned
}
return handler(ctx, req)
}
}
// StreamServerInterceptor returns an interceptor that annotates incoming gRPC requests with an Id.
// Ids are stored in the gRPC request metadata and are generated using github.com/renstrom/shortuuid.
// If replace is false, this is only done for requests that do not already have an Id.
func StreamServerInterceptor(replace bool) grpc.StreamServerInterceptor {
return func(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
ctx := stream.Context()
if _, ok := FromContext(ctx); !ok || replace {
id := shortuuid.New()
ctx, _ = AddToIncomingContext(ctx, id) // If the operation fails, the original context is returned
}
wrapped := grpc_middleware.WrapServerStream(stream)
wrapped.WrappedContext = ctx
return handler(srv, wrapped)
}
}