Question

Your team's network automation stack is defined in a docker-compose.yml. The 'automation' service must reach the 'nautobot' service by hostname for source-of-truth lookups. A colleague wrote the file below, but 'automation' cannot resolve the hostname 'nautobot':

services:
  nautobot:
    image: networktocode/nautobot:latest
    networks:
      - sot-net
  automation:
    image: registry.local/automation:1.4
    networks:
      - ci-net
    links:
      - nautobot

networks:
  sot-net:
  ci-net:

Why does name resolution fail, and what is the correct fix?

Accepted Answer

The two services are attached to different user-defined networks (sot-net and ci-net); attach both services to a shared network so Docker's embedded DNS can resolve 'nautobot'.

Answer

The 'links' directive is deprecated and does nothing; replace it with a 'depends_on' entry pointing to nautobot to enable DNS resolution.

Answer

The nautobot service is missing an 'expose' key; add 'expose: [8080]' so its hostname becomes resolvable on the network.

Answer

The automation image tag is pinned to 1.4, which lacks DNS client support; change it to 'latest' so the container can query Docker DNS.