Getting an error in open telemetry collector as 415 unsupported media type

[iliyas86]

I am trying to query oen telemetry collector through below mentiorn API, but getting an error as

Request: Request: http://127.0.0.1:4318/v1/metrics

Browser:
405 method not allowed, supported: [POST]

Prometheus:
Even tried to connect to Prometheus, but the connection is getting refused.

Postman:
"415 unsupported media type, supported: [application/json, application/x-protobuf]"
In case, if I pass Content-Type "application/json", getting some junk data:

          {
                       "code": 3,
                        "message":"ReadObjectCB: expect { or n, but found 
           }

Setup Info:
Using Docker desktop where All pods are hosted and running.

Configuration:

docker compose:

otel-collector:
image: otel/opentelemetry-collector:latest
volumes:
- ./otel-collector-config.yaml:/etc/otel-collector-config.yaml
ports:
- "4317:4317"
- "4318:4318" # Expose OTLP HTTP endpoint
networks:
- HACK
prometheus:
image: quay.io/prometheus/prometheus:v2.42.0
volumes:
- ./prometheus.yml:/etc/prometheus/prometheus.yml
ports:
- "9090:9090"
networks:
- HACK
depends_on:
- otel-collector

prometheus.yml

global:
scrape_interval: 100s
scrape_timeout: 90s
scrape_configs:

• job_name: 'otel-collector'
  metrics_path: /metrics
  static_configs:
  • targets:
    • '172.27.83.69:4318'

otel-collector-config.yaml

receivers:
otlp:
protocols:
grpc:
endpoint: "localhost:4319"
http:
endpoint: "localhost:4317"

exporters:
prometheus:
endpoint: "localhost:4318"
send_timestamps: true
metric_expiration: 180m
resource_to_telemetry_conversion:
enabled: true

service:
pipelines:
traces:
receivers: [otlp]
processors: [batch]
exporters: [prometheus]

[lextas]

According to the readme you should be able to configure CORS origins on the receiver configuration (in your tempo.yaml). You should also be able to use a wildcard - "*" but that doesn't work for me. Make sure you remove and restart your containers to ensure the new configuration is loaded.

receivers:
  otlp:
    protocols:
      http:
        include_metadata: true
        auth:
          authenticator: some-authenticator-extension
        cors:
          allowed_origins:
            - https://foo.bar.com
            - https://*.test.com
          allowed_headers:
            - Example-Header
          max_age: 7200
        endpoint: 0.0.0.0:55690

[kasbuunk]

I had the same error. As it turned out, I had configured to export to Tempo's gRPC endpoint, but I was using the http trace exporter:

import (
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
)

Switching to the http port (4318) or using the grpc exporter package fixed it for me.