Problems in Docker, changes for file_sd_configs

I was trying to Dockerize the proxy in my personal fork

Because I would like to use the file_sd_configs in Prometheus scrape config to get the scrape endpoints dynamically, I decided to send the fqdn along with the port. If I check the /clients endpoint, I now have valid scrape configs in there. So far so good.

I did some tests locally in Visual Studio Code, everything worked like a charm. As soon as I start the Docker Container for the proxy, the problems begin. The response for /poll sometimes works and sometimes not. If I do the exact same thing without Docker it's working reliable.

Does anyone have an idea? I stuck in this for more than one day. Probably someone with Go and Docker Know-How can support me here.

In meantime I will try to setup a remote debugging environment for Go and Docker to get a better overview.

Many Thanks
e-bits

Notice:
I'm in clear mind that I will loose the ability to scan different Ports if I inject the port already on client start.

Start with the Dockerfile in the linked fork and compare the Docker and local behavior of the /poll endpoint. Check the /clients response and the file_sd_configs change, then use the proposed Go/Docker remote debugging setup to isolate the intermittent failure. Done means the cause is identified and /poll works reliably in the container.