Debian 9下Docker配置求助：无法通过域名访问主机

Hey there! Let's work through why your sitename.loc domain isn't resolving, even though you can reach the host via its IP (172.18.0.7). The errors you’re seeing—ERR_NAME_NOT_RESOLVED and DNS_PROBE_FINISHED_NXDOMAIN—point straight to a DNS resolution problem, so let’s start there before diving into iptables:

1. Check Local Hosts File (Quickest Fix for Local Domains) #

.loc is a local-use domain that public DNS servers don’t recognize by default. If you’re accessing this from the same machine or a local network device, you probably need to manually map the domain to your host’s IP:

• On the device you’re using to access sitename.loc, edit the hosts file:

  sudo nano /etc/hosts # For Linux/macOS
  # On Windows: Open C:\Windows\System32\drivers\etc\hosts with Notepad (run as admin)
  

• Add this line at the bottom:

  172.18.0.7    sitename.loc
  

• Save the file, then try accessing the domain again. If this works, the issue was just a missing local DNS mapping.

2. Test DNS Resolution Directly #

If the hosts file fix doesn’t work, let’s verify if your system can actually resolve the domain:

• Run these commands on your Debian 9 host to check DNS lookup:

  nslookup sitename.loc
  dig sitename.loc
  

• If both return NXDOMAIN, your configured DNS servers have no record for sitename.loc. You have two options here:
  • Set up a local DNS server (like dnsmasq) on your network that can resolve .loc domains to your host’s IP.
  • Add an A record pointing sitename.loc to 172.18.0.7 in your network’s main DNS server.

3. Check Docker's DNS Configuration #

Docker sometimes modifies the host’s DNS settings, which could interfere with local domain resolution:

• Check your Debian host’s resolv.conf file:

  cat /etc/resolv.conf
  

• If you see Docker-specific DNS entries (like 127.0.0.11), override the DNS for your Docker services in docker-compose.yml to use your local network DNS:

  services:
    your-service-name:
      # ... other service configs ...
      dns:
        - 192.168.1.1 # Replace with your local DNS server IP
        - 8.8.8.8 # Fallback to Google DNS
  

• Recreate the containers with docker-compose down && docker-compose up -d after making this change.

4. Rule Out iptables (Less Likely, But Worth Checking) #

Since you already disabled the firewall, iptables is probably not the culprit—but let’s confirm:

• List all iptables rules to check if DNS traffic (UDP port 53) is blocked:

  iptables -L -n | grep 53
  

• If you see any DROP rules targeting port 53, temporarily flush the rules to test:

  sudo iptables -F
  

• Try accessing the domain again. If this works, adjust your iptables rules to allow DNS traffic permanently.

内容的提问来源于stack exchange，提问作者Juljan