allow otlp clients to use existing grpc connection

Signed-off-by: Tonis Tiigi <[email protected]>

CHANGELOG.md

@@ -42,6 +42,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Several builtin resource detectors now correctly populate the schema URL. (#1938)
 - Creates package `go.opentelemetry.io/otel/exporters/otlp/otlpmetric` that defines a metrics exporter that uses a `otlpmetric.Client` to send data.
   Creates package `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc` implementing a gRPC `otlpmetric.Client` and offers convenience functions, `New` and `NewUnstarted`, to create an `otlpmetric.Exporter`.(#1991)
+- Adds `otlptracegrpc.WithGRPCConn` and `otlpmetricgrpc.WithGRPCConn` for reusing existing gRPC connection. (#2002)
 
 ### Changed
 

exporters/otlp/otlpmetric/internal/connection/connection.go

@@ -220,6 +220,10 @@ func (c *Connection) setConnection(cc *grpc.ClientConn) bool {
 }
 
 func (c *Connection) dialToCollector(ctx context.Context) (*grpc.ClientConn, error) {
+	if c.cfg.GRPCConn != nil {
+		return c.cfg.GRPCConn, nil
+	}
+
 	dialOpts := []grpc.DialOption{}
 	if c.cfg.ServiceConfig != "" {
 		dialOpts = append(dialOpts, grpc.WithDefaultServiceConfig(c.cfg.ServiceConfig))

exporters/otlp/otlpmetric/internal/otlpconfig/options.go

@@ -64,6 +64,7 @@ type (
 		ReconnectionPeriod time.Duration
 		ServiceConfig      string
 		DialOptions        []grpc.DialOption
+		GRPCConn           *grpc.ClientConn
 		RetrySettings      RetrySettings
 	}
 )

exporters/otlp/otlpmetric/otlpmetricgrpc/options.go

@@ -116,6 +116,14 @@ func WithDialOption(opts ...grpc.DialOption) Option {
 	})}
 }
 
+// WithGRPCConn allows reusing existing gRPC connection when it has already been
+// established for other services. When set, other dial options will be ignored.
+func WithGRPCConn(conn *grpc.ClientConn) Option {
+	return wrappedOption{otlpconfig.NewGRPCOption(func(cfg *otlpconfig.Config) {
+		cfg.GRPCConn = conn
+	})}
+}
+
 // WithTimeout tells the client the max waiting time for the backend to process
 // each metrics batch. If unset, the default will be 10 seconds.
 func WithTimeout(duration time.Duration) Option {

exporters/otlp/otlptrace/internal/connection/connection.go

@@ -220,6 +220,10 @@ func (c *Connection) setConnection(cc *grpc.ClientConn) bool {
 }
 
 func (c *Connection) dialToCollector(ctx context.Context) (*grpc.ClientConn, error) {
+	if c.cfg.GRPCConn != nil {
+		return c.cfg.GRPCConn, nil
+	}
+
 	dialOpts := []grpc.DialOption{}
 	if c.cfg.ServiceConfig != "" {
 		dialOpts = append(dialOpts, grpc.WithDefaultServiceConfig(c.cfg.ServiceConfig))

exporters/otlp/otlptrace/internal/otlpconfig/options.go

@@ -75,6 +75,7 @@ type (
 		ReconnectionPeriod time.Duration
 		ServiceConfig      string
 		DialOptions        []grpc.DialOption
+		GRPCConn           *grpc.ClientConn
 		RetrySettings      RetrySettings
 	}
 )

exporters/otlp/otlptrace/otlptracegrpc/options.go

@@ -115,6 +115,14 @@ func WithDialOption(opts ...grpc.DialOption) Option {
 	})}
 }
 
+// WithGRPCConn allows reusing existing gRPC connection when it has already been
+// established for other services. When set, other dial options will be ignored.
+func WithGRPCConn(conn *grpc.ClientConn) Option {
+	return wrappedOption{otlpconfig.NewGRPCOption(func(cfg *otlpconfig.Config) {
+		cfg.GRPCConn = conn
+	})}
+}
+
 // WithTimeout tells the driver the max waiting time for the backend to process
 // each spans batch. If unset, the default will be 10 seconds.
 func WithTimeout(duration time.Duration) Option {