I'm a bit of a newbie with this, but I haven't been able to find an explanation. Here's my issue. I'm trying to get Prometheus and Grafana configured on an AWS Fargate instance. I'm testing inside a Docker instance on my desktop. Both environments were coming up, but Grafana was reporting no data.
- name: Prometheus
I started the container with this:
docker run -d \
--name prometheus \
--hostname prometheus \
-p 8110:22 \
-p 9091:9091 \
When I couldn't figure out why Grafana reported no data, I restarted the container, adding -p 9090:9090 so that I could access Prometheus's graphing interface. And suddenly Grafana shows data.
Which has me deeply puzzled. I don't know how Grafana works under the hood, and so far I haven't found an explanation. So I'm wondering why port-mapping fixed the problem.
Do I need to configure Grafana to access Prometheus via an externally-resolved URL (that is, one that resolves in my browser, not from Grafana itself)?
I hadn't planned on exposing Prometheus itself to the world, but maybe I have to.
Additional Info: Within AWS, my Grafana charts all have a red warning indicator for each chart, and the rollover says "Not allowed to request resource". I haven't found any docs yet on what can cause this. Still digging.