Fixing Docker DNS Resolution Issue in NixOS

If you’re using NixOS and encountering the following error when trying to pull images from Docker Hub:

Error response from daemon: Get "https://registry-1.docker.io/v2/": dial tcp: lookup registry-1.docker.io: Temporary failure in name resolution

this usually indicates a DNS resolution problem with Docker. Since NixOS uses a declarative configuration, we need to explicitly set the correct DNS resolver to fix the issue.

Cause of the Issue

Docker relies on the system’s DNS configuration to resolve domain names. In some NixOS setups, the /etc/resolv.conf file may not be correctly configured, leading to DNS resolution failures.

Solution: Configure resolv.conf in configuration.nix

To fix this issue, we need to ensure that NixOS properly sets the DNS resolver for Docker. Add the following snippet to your configuration.nix:

{ config, pkgs, ... }:

{
  environment.etc = {
    "resolv.conf".text = "nameserver 8.8.8.8";
  };
}

This configuration explicitly sets the DNS resolver to Google’s 8.8.8.8, ensuring that DNS queries are correctly resolved.

Applying the Fix