# Prometheus scrape job cannot reach the metrics

**URL:** <https://meta.discourse.org/t/prometheus-scrape-job-cannot-reach-the-metrics/264902>\
**Category:** Self-hosting\
**Tags:** prometheus\
**Created:** [May 13, 2023, 5:23pm UTC](https://meta.discourse.org/t/prometheus-scrape-job-cannot-reach-the-metrics/264902 "2023-05-13T17:23:40Z")\
**Posts on this page:** 1\
**Showing post:** 11

<div class="post-metadata">

**Author:** ![leonardo](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/leonardo/32/228634_2.png) [@leonardo](https://meta.discourse.org/u/leonardo)\
**Post date:** [May 15, 2023, 4:41pm UTC](https://meta.discourse.org/t/prometheus-scrape-job-cannot-reach-the-metrics/264902/11 "2023-05-15T16:41:24Z")

</div>

> [@pfaffman](#):
>
> You need to access it using the host name, not the container name.

What Jay meant here is that you need to use the configured hostname (`DISCOURSE_HOSTNAME` in your container .yml definition) as opposed to any hostname that happens to resolve to the correct IP.

This is deliberate, so that you can’t trivially reverse proxy a public instance from just anywhere, and so that only the configured hostname is accepted:

```bash
$ curl -I https://try.discourse.org/about.json
HTTP/2 200
server: nginx
date: Mon, 15 May 2023 16:25:05 GMT
content-type: application/json; charset=utf-8
[...]

# the following is equivalent to creating a DNS record at
# try.somebogusreverseproxy.com pointing to the same IP address as try.discourse.org,
# and then requesting https://try.somebogusreverseproxy.com/about.json
$ curl -H 'Host: try.somebogusreverseproxy.com' -I https://try.discourse.org/about.json
HTTP/2 404
cache-control: no-cache
content-length: 1427
content-type: text/html
cdck-proxy-id: app-router-tiehunter02.sea1
cdck-proxy-id: app-balancer-tieinterceptor1b.sea1

```

Conversely, if you try this:

```bash
curl -H 'Host: YOUR_CONFIGURED_HOSTNAME' -I https://discourse_app/metrics

```

it should work, but it’s a hack. The expectation is that you’ll set up DNS as required so that Discourse can be reached at its configured hostname transparently:

```bash
curl -I https://YOUR_CONFIGURED_HOSTNAME/metrics

```

How to do that depends greatly on your requirements, but the simplest option is to set up an alias in `/etc/hosts` from where your HTTP requests originate.

---

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