hashicorp/nomad · error

-dev=connect uses network namespaces: could not find public

Error message

-dev=connect uses network namespaces: could not find public network interface

What it means

When interface enumeration succeeds but returns an empty list, -dev-connect cannot find a public network interface to bind and returns this error (message rendered from the same typo'd format string) with the static reason.

Source

Thrown at command/agent/config.go:1758

		mode.iface = "Loopback Pseudo-Interface 1"
		return nil
	}
	if runtime.GOOS == "darwin" {
		mode.bindAddr = "127.0.0.1"
		mode.iface = "lo0"
		return nil
	}
	if mode != nil && mode.connectMode {
		// if we hit either of the errors here we're in a weird situation
		// where syscalls to get the list of network interfaces are failing.
		// rather than throwing errors, we'll fall back to the default.
		ifAddrs, err := sockaddr.GetDefaultInterfaces()
		errMsg := "-dev=connect uses network namespaces: %v"
		if err != nil {
			return fmt.Errorf(errMsg, err)
		}
		if len(ifAddrs) < 1 {
			return fmt.Errorf(errMsg, "could not find public network interface")
		}
		iface := ifAddrs[0].Name
		mode.iface = iface
		mode.bindAddr = "0.0.0.0" // allows CLI to "just work"
		return nil
	}
	mode.bindAddr = "127.0.0.1"
	mode.iface = "lo"
	return nil
}

// DevConfig is a Config that is used for dev mode of Nomad.
func DevConfig(mode *devModeConfig) *Config {
	if mode == nil {
		mode = &devModeConfig{defaultMode: true}
		mode.networkConfig()
	}
	conf := DefaultConfig()

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Ensure the environment has a routable non-loopback interface (attach a bridge/network).
2. Use a different dev environment (host network, default docker bridge).
3. Fall back to plain -dev mode which does not need a public interface.

Example fix

# before (no interfaces)
docker run --network none nomad-dev nomad agent -dev-connect
# after
docker run --network bridge nomad-dev nomad agent -dev-connect

ifAddrs, _ := sockaddr.GetDefaultInterfaces()
if len(ifAddrs) == 0 {
  return errors.New("no public interface; use a networked environment or -dev")
}

When it happens

Trigger: sockaddr.GetDefaultInterfaces() returns 0 interfaces during networkConfig() — e.g. loopback-only containers, freshly created netns with no links configured.

Common situations: Running inside a minimal network namespace (ip netns with only lo); docker run --network none; VMs with interfaces not yet up.

Related errors

• -dev=connect uses network namespaces: %v
• -dev-connect uses network namespaces and is only supported f
• network namespace already exists but was misconfigured
• network already configured but not found in state
• no CNI network config found

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/d961cd99ef494940. Report an issue: GitHub.