OTEL_EXPORTER_OTLP_ENDPOINT "no such host" in CI

By Kaveh Alemi·Latchkey

The OTLP exporter could not resolve the hostname in OTEL_EXPORTER_OTLP_ENDPOINT: DNS returned "no such host." Unlike connection refused, the dial never even reached an IP because the name does not resolve.

What this error means

Logs show "dial tcp: lookup otel-collector on ...: no such host" or "no such host" from the exporter, and no telemetry is delivered.

failed to upload metrics: Post "http://otel-collector:4318/v1/metrics":
dial tcp: lookup otel-collector on 127.0.0.11:53: no such host

Common causes

The service name is not resolvable from this job

A service hostname like otel-collector only resolves on the same Docker network; a job not attached to that network cannot look it up.

A typo or wrong scheme in the endpoint

A misspelled host, a missing scheme, or a stale endpoint value makes DNS resolution fail outright.

How to fix it

Use a hostname the runner can resolve

1. For a service container, attach the job to the same network and use the service alias.
2. For an external collector, use its real DNS name or IP.
3. Re-run and confirm the lookup succeeds.

services:
  otel-collector:
    image: otel/opentelemetry-collector:latest
    ports: ['4318:4318']
# then export to the published port:
env:
  OTEL_EXPORTER_OTLP_ENDPOINT: http://localhost:4318

Correct the endpoint value

Include the scheme and the exact host, e.g. http://host:4318, so DNS has a valid name to resolve.

How to prevent it

• Reference collectors by names the runner can actually resolve.
• Include the scheme and port in the OTLP endpoint.
• Use published ports on localhost when a service container is involved.

Frequently asked questions

Related guides

References

• GitHub Actions documentation