Exception with OtlpGrpcSpanExporter and latest grpc

[croudet]

Describe the bug
Got an exception when trying to build and OtlpGrpcSpanExporter not using default okhttp exporter but opentelemetry-exporter-sender-grpc-managed-channel

Exception in thread "main" java.lang.NullPointerException: channel
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:921)
	at io.grpc.ClientInterceptors.intercept(ClientInterceptors.java:87)
	at io.grpc.ClientInterceptors.intercept(ClientInterceptors.java:74)
	at io.opentelemetry.exporter.sender.grpc.managedchannel.internal.UpstreamGrpcSenderProvider.createSender(UpstreamGrpcSenderProvider.java:59)
	at io.opentelemetry.exporter.internal.grpc.GrpcExporterBuilder.build(GrpcExporterBuilder.java:158)
	at io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporterBuilder.build(OtlpGrpcSpanExporterBuilder.java:189)

Steps to reproduce

public static void main(String... args) {
        OtlpGrpcSpanExporter.builder()
                .setEndpoint("https://collector-service:4317")
                .build();

What did you expect to see?
No Exception.

What did you see instead?
An exception because channel is null and io.grpc.ClientInterceptors.intercept checks that.

What version and what artifacts are you using?
grpc-java: 1.58.0

<dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-exporter-otlp</artifactId>
      <version>1.31.0</version>
      <exclusions>
        <exclusion>
          <groupId>io.opentelemetry</groupId>
          <artifactId>opentelemetry-exporter-sender-okhttp</artifactId>
        </exclusion>
        <exclusion>
          <groupId>com.squareup.okhttp3</groupId>
          <artifactId>okhttp</artifactId>
        </exclusion>
      </exclusions>
 </dependency>
 <dependency>
      <groupId>io.opentelemetry</groupId>
      <artifactId>opentelemetry-exporter-sender-grpc-managed-channel</artifactId>
      <version>1.31.0</version>
 </dependency>

Environment
Compiler: OpenJDK Runtime Environment Temurin-17.0.8+7 (build 17.0.8+7)
OS: Windows

[laurit]

As far as I understand you should supply the channel instead of the endpoint like it is done in

opentelemetry-java/exporters/otlp/all/src/testGrpcNetty/java/io/opentelemetry/exporter/otlp/trace/OtlpGrpcNettySpanExporterTest.java

Line 37 in 3827ee1

try (Closeable exporter = OtlpGrpcSpanExporter.builder().setChannel(channel).build()) {

to use the upstream grpc implementation. Did this worke in a previous version?

[croudet]

Yes, but setChannel is deprecated, I wonder if there was another way to initialize it.

[jack-berg]

Yes @laurit is correct.

#4531 describes a use case where setEndpoint is insufficient and requests that we do not deprecate setChannel. In general, we want to encourage use of the OkHttp exporter and expand the capabilities of it where missing. I'm going to close this in favor of #4531, but it would be helpful if you could describe your use case for using opentelemetry-exporter-sender-grpc-managed-channel on that issue.

[croudet]

it is just that okhttp brings kotlin dependencies, and in the project I plan to use it, we already have grpc-java.

[jack-berg]

If you're on java 11+, consider using opentelemetry-exporter-sender-jdk. It only supports OtlpHttp{Signal}Exporters (i.e. the http/protobuf) version of the protocol), but uses the built in JDK HttpClient and has zero transitive dependencies.

[fax4ever]

@jack-berg is there a way to setChannel using autoconfigure? thanks