allow otlp clients to use existing grpc connection (#2002)

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -8,6 +8,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Added
+
+- Adds `otlptracegrpc.WithGRPCConn` and `otlpmetricgrpc.WithGRPCConn` for reusing existing gRPC connection. (#2002)
+
 ## [1.0.1] - 2021-10-01
 
 ### Fixed

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

@@ -75,6 +75,7 @@ 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

@@ -221,6 +221,10 @@ 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

@@ -58,6 +58,7 @@ type (
 		ReconnectionPeriod time.Duration
 		ServiceConfig      string
 		DialOptions        []grpc.DialOption
+		GRPCConn           *grpc.ClientConn
 	}
 )
 

exporters/otlp/otlptrace/otlptracegrpc/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 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 {