ProjectStack
docker

Temporary failure in name resolution / Could not resolve host

A process inside your container can't resolve domain names. DNS resolution is failing, which means the container can't look up the IP address for any external hostname. This is a container networking configuration issue, not a problem with the application code itself.

Common causes

  • Docker's internal DNS is unreachable — this can happen if the host DNS is misconfigured
  • The container is using host networking mode with a broken /etc/resolv.conf on the host
  • A custom Docker network with no DNS configuration, or the DNS option wasn't set
  • Firewall or VPN software on the host blocking DNS traffic from reaching Docker containers

How to fix it

  1. Test basic DNS from a container: docker run --rm busybox nslookup google.com
  2. Set explicit DNS servers for Docker: add {"dns": ["8.8.8.8", "8.8.4.4"]} to /etc/docker/daemon.json, then restart Docker
  3. For a single container: docker run --dns 8.8.8.8 myimage
  4. In Docker Compose: add dns: ["8.8.8.8"] under the service definition

Example

$ docker run myapp curl: (6) Could not resolve host: api.example.com Temporary failure in name resolution

Container can't reach external services because DNS isn't working inside the container

Related Docker Errors

Cannot connect to Docker daemonPermission denied connecting to Docker socketDocker daemon not running on this hostImage not found or pull access deniedImage manifest not found (tag doesn't exist)

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