Changing Speedtest DNS Configuration?

[geoscoutCJ]

Hey all,

I am pretty new to working with docker containers and I have run into a question I am having trouble googling my way out of. I want to change the speedtest to use a different IP for it's DNS resolution instead of the local host. Essentially, I want it pointing at my secondary PiHole so it does not throw off my main PiHole dashboard metrics.

I am guessing I would need to change a configuration in the Prometheus container but I haven't the slightest clue as to where to start with that.

Anyone have an idea how I would go about this or is there an easier way to fix the problem I am trying to solve?

Thanks!
Caleb

[martinbrose]

Isn't that something you can specify in the docker-compose for the specific service?

See the following discussion: https://stackoverflow.com/questions/41717180/docker-compose-container-using-host-dns-server

[geoscoutCJ]

Thanks for the suggestion! That was exactly what I was looking for and could not find before.

I had tried editing just the /etc/resolv.conf file but it seemed that docker was not picking that up automatically. I had found a solution to add a global configuration to all docker containers to use specified IPs (Ref: https://serverfault.com/questions/612075/how-to-configure-custom-dns-server-with-docker) but that was not ideal since I really only wanted to have the ping and speedtest containers using the backup by default.

For anyone interested, this is how my ping and speedtest entries look in the docker-compose.yml file now:

ping:
    tty: true
    stdin_open: true
    expose:
      - 9115
    ports:
      - 9115:9115
    image: prom/blackbox-exporter
    restart: always
    volumes:
      - ./blackbox/config:/config
    command:
      - '--config.file=/config/blackbox.yml'
    networks:
      - back-tier
    dns:
      - my.2ndpihole.address.here
      - my.1stpihole.address.here

  speedtest:
    tty: true
    stdin_open: true
    expose:
      - 9798
    ports:
      - 9798:9798
    image: miguelndecarvalho/speedtest-exporter
    restart: always
    networks:
      - back-tier
    dns:
      - my.2ndpihole.address.here
      - my.1stpihole.address.here

All the best,
Caleb