[otelgrpc] Do not panic for nil instruments (#4875)

* Do not panic for nil instr in grpc

* Add changelog entry

* Apply lint

* Use noop pkg hist impls

CHANGELOG.md

@@ -13,6 +13,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add the new `go.opentelemetry.io/contrib/instrgen` package to provide auto-generated source code instrumentation. (#3068, #3108)
 - Add peer attributes to spans recorded by `NewClientHandler`, `NewServerHandler` in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#4873)
 
+### Fixed
+
+- Do not panic in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc` if `MeterProvider` returns a `nil` instrument. (#4875)
+
 ## [1.22.0/0.47.0/0.16.0/0.2.0] - 2024-01-18
 
 ### Added

instrumentation/google.golang.org/grpc/otelgrpc/config.go

@@ -18,6 +18,7 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/noop"
 	"go.opentelemetry.io/otel/propagation"
 	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
 	"go.opentelemetry.io/otel/trace"
@@ -89,34 +90,49 @@ func newConfig(opts []Option, role string) *config {
 		metric.WithUnit("ms"))
 	if err != nil {
 		otel.Handle(err)
+		if c.rpcDuration == nil {
+			c.rpcDuration = noop.Float64Histogram{}
+		}
 	}
 
 	c.rpcRequestSize, err = c.meter.Int64Histogram("rpc."+role+".request.size",
 		metric.WithDescription("Measures size of RPC request messages (uncompressed)."),
 		metric.WithUnit("By"))
 	if err != nil {
 		otel.Handle(err)
+		if c.rpcRequestSize == nil {
+			c.rpcRequestSize = noop.Int64Histogram{}
+		}
 	}
 
 	c.rpcResponseSize, err = c.meter.Int64Histogram("rpc."+role+".response.size",
 		metric.WithDescription("Measures size of RPC response messages (uncompressed)."),
 		metric.WithUnit("By"))
 	if err != nil {
 		otel.Handle(err)
+		if c.rpcResponseSize == nil {
+			c.rpcResponseSize = noop.Int64Histogram{}
+		}
 	}
 
 	c.rpcRequestsPerRPC, err = c.meter.Int64Histogram("rpc."+role+".requests_per_rpc",
 		metric.WithDescription("Measures the number of messages received per RPC. Should be 1 for all non-streaming RPCs."),
 		metric.WithUnit("{count}"))
 	if err != nil {
 		otel.Handle(err)
+		if c.rpcRequestsPerRPC == nil {
+			c.rpcRequestsPerRPC = noop.Int64Histogram{}
+		}
 	}
 
 	c.rpcResponsesPerRPC, err = c.meter.Int64Histogram("rpc."+role+".responses_per_rpc",
 		metric.WithDescription("Measures the number of messages received per RPC. Should be 1 for all non-streaming RPCs."),
 		metric.WithUnit("{count}"))
 	if err != nil {
 		otel.Handle(err)
+		if c.rpcResponsesPerRPC == nil {
+			c.rpcResponsesPerRPC = noop.Int64Histogram{}
+		}
 	}
 
 	return c

instrumentation/google.golang.org/grpc/otelgrpc/config_test.go

@@ -0,0 +1,58 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otelgrpc
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/embedded"
+)
+
+func TestNilInstruments(t *testing.T) {
+	mp := meterProvider{}
+	c := newConfig([]Option{WithMeterProvider(mp)}, "test")
+
+	ctx := context.Background()
+	assert.NotPanics(t, func() { c.rpcDuration.Record(ctx, 0) }, "rpcDuration")
+	assert.NotPanics(t, func() { c.rpcRequestSize.Record(ctx, 0) }, "rpcRequestSize")
+	assert.NotPanics(t, func() { c.rpcResponseSize.Record(ctx, 0) }, "rpcResponseSize")
+	assert.NotPanics(t, func() { c.rpcRequestsPerRPC.Record(ctx, 0) }, "rpcRequestsPerRPC")
+	assert.NotPanics(t, func() { c.rpcResponsesPerRPC.Record(ctx, 0) }, "rpcResponsesPerRPC")
+}
+
+type meterProvider struct {
+	embedded.MeterProvider
+}
+
+func (meterProvider) Meter(string, ...metric.MeterOption) metric.Meter {
+	return meter{}
+}
+
+type meter struct {
+	// Panic for non-implemented methods.
+	metric.Meter
+}
+
+func (meter) Int64Histogram(string, ...metric.Int64HistogramOption) (metric.Int64Histogram, error) {
+	return nil, assert.AnError
+}
+
+func (meter) Float64Histogram(string, ...metric.Float64HistogramOption) (metric.Float64Histogram, error) {
+	return nil, assert.AnError
+}