Prometheus config file a bit misleading about graylog-docker

[supahgreg]

As of 4.1 Graylog has a built-in Prometheus exporter that should be used instead of the archived project you mentioned. This isn't anything specific to the Docker image.

Try adding these environment variables:

• GRAYLOG_PROMETHEUS_EXPORTER_ENABLED=true
• GRAYLOG_PROMETHEUS_EXPORTER_BIND_ADDRESS=0.0.0.0:9833

... and then add port 9833:9833/tcp and restart rebuild. After that you should be able to hit http://$SOME_HOST_IP:9833/ and see metrics.

[suntereo]

Thank you Greg! I can confirm your steps do work on my end.

But I'm still confused. The graylog.conf file shows 127.0.0.1:

# IP address and port for the Prometheus exporter HTTP server.
# Default: 127.0.0.1:9833
#prometheus_exporter_bind_address = 127.0.0.1:9833

Because of this, 127.0.0.1 is what I was trying to use. But this fails on my end with:

Your advice to use 0.0.0.0 does resolve this error.

But if you use 127.0.0.1:9833, does it work on your end? If not, shouldn't graylog.conf be updated to show 0.0.0.0?

[supahgreg]

The difference is that you're running Graylog within a Docker container rather than directly on the host system. By default, 127.0.0.1 in your container is local to the container (i.e. it's not the 127.0.0.1 of your host system). 0.0.0.0 binds to all available interfaces in the container, including the one used when exposing ports. Docker's networking documentation covers all of this in detail.

127.0.0.1:9833 is a reasonable default, as it prevents unintentionally exposing metrics.

[suntereo]

Thanks again. That is very helpful.

I bet others will blindly follow the comments in the graylog.conf and have it fail like I did. But I suppose they can just find this thread and get the solution they need.