Go Prometheus guide: healthcheck uses wrong port and lacks curl

[take-shino]

Is this a docs issue?

• My issue is about the documentation content or website

Type of issue

Information is incorrect

Description

The Go + Prometheus + Grafana guide's sample starts the API successfully, but the container remains unhealthy.

I reproduced this using Docker Desktop on Windows 11.

The API itself was running, and Prometheus could access /metrics. The API logs showed successful HTTP 200 responses. However, docker compose ps reported the API container as unhealthy.

Inspecting the health status showed:

exec: "curl": executable file not found in $PATH

There are two related inconsistencies in the current sample:

1. compose.yaml and the Compose example in README.md check http://localhost:8080/health, while main.go listens on :8000 and the Dockerfile exposes port 8000.
2. The healthcheck invokes curl, but the final alpine:3.17 image does not install it.

Relevant current configuration:

healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:8080/health"]

router.Run(":8000")

FROM alpine:3.17 AS final
EXPOSE 8000

After changing the healthcheck port to 8000, installing curl, and rebuilding the API image, the container changed from unhealthy to healthy.

Sample repository: https://github.com/dockersamples/go-prometheus-monitoring

Location

https://docs.docker.com/guides/go-prometheus-monitoring/

Suggestion

Update the healthcheck in both compose.yaml and the README example to use port 8000:

healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:8000/health"]

Also make the healthcheck executable available in the final image, for example:

RUN apk add --no-cache curl

Alternatively, use a healthcheck command that is already available in the final image.