HTTP receiver doesn't work

[IvanVan]

Describe the bug
Got the following message error when use http receiver

Sep 22, 2021 5:21:28 PM io.opentelemetry.sdk.internal.ThrottlingLogger doLog
WARNING: Failed to export spans. Server responded with HTTP status code 404. Error message: Unable to parse response body, HTTP status message: Not Found

Steps to reproduce
Run docker compose with the following docker-compose.yaml

version: "2"
services:

  zipkin-all-in-one:
    image: openzipkin/zipkin:latest
    ports:
      - "9411:9411"

  otel-collector:
    image: otel/opentelemetry-collector:latest
    command: ["--config=otel-local-config.yaml", "${OTELCOL_ARGS}"]
    volumes:
      - ${PWD}/config.yaml:/otel-local-config.yaml
    ports:
      - "4318:4318"

and config.yaml

receivers:
  otlp:
    protocols:
      http:

exporters:
  zipkin:
    endpoint: "http://zipkin-all-in-one:9411/api/v2/spans"
    format: proto

  logging:

processors:
  batch:

service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: [batch]
      exporters: [logging, zipkin]

Run simple Java app:

import io.opentelemetry.sdk.autoconfigure.OpenTelemetrySdkAutoConfiguration;
import io.opentelemetry.api.GlobalOpenTelemetry;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.SpanKind;
import io.opentelemetry.api.trace.Tracer;
import java.util.Scanner;

public class Main
{
  public static void main(String[] args)
  {
    System.setProperty("otel.service.name", "Simple server");
    System.setProperty("otel.experimental.exporter.otlp.protocol", "http/protobuf");
    System.setProperty("otel.exporter.otlp.endpoint", "http://localhost:4318");

    OpenTelemetrySdkAutoConfiguration.initialize();

    while (true) {
      Scanner scanner = new Scanner(System.in);
      String in = scanner.nextLine();
      if (in.equals("exit")) {
        break;
      }
      Tracer tracer = GlobalOpenTelemetry.getTracer("Simple server");
      Span outGoing = tracer.spanBuilder("Simple server").setSpanKind(SpanKind.CLIENT).startSpan();
      outGoing.end();
    }
  }
}

What did you expect to see?
Expect to see spans in zipkin

What did you see instead?
Error message

What version did you use?
opentelemetry - 1.6.0
com.google.protobuf - protobuf-java - 3.17.3

[IvanVan]

@jack-berg Could you tell me please if you have any ideas why it happens?

[jack-berg]

Hi @IvanVan. I believe this is related to this issue in opentelemetry-java.

Can you try adding /v1/traces to the the system property?

System.setProperty("otel.exporter.otlp.endpoint", "http://localhost:4318/v1/traces");
// or if you need metrics as well:
// System.setProperty("otel.exporter.otlp.traces.endpoint", "http://localhost:4318/v1/traces");

I'm working on getting a fix for this in opentelemetry-java, but for now you should be able to work around it.

[IvanVan]

Thank you so much @jack-berg for answering and such quick response!
Now it works as expected 🙂