No machine-id detected in docker containers

[Lachlan Donald]

It appears that Docker doesn't expose /var/lib/dbus/machine-id or /etc/machine-id, so no machine-id gets detected inside docker containers.

[Alessandro Dionisi]

Did you try to share the file from the host to the container?

For example:

version: '3'
services:
  service:
    image: image
    ports:
    - 8080:8080
    restart: always
    network_mode: "host"
    volumes:
    - /etc/machine-id:/etc/machine-id
    - /var/lib/dbus/machine-id:/var/lib/dbus/machine-id

[Mark]

This is a great library, thanks so much for writing it.

It would be great if docker containerisation were detected, and then a unique container ID or some information was used as the machine ID - or if it exposed a Docker ID and the machine ID, and both could be used as a third unique ID.

[Chen Mingliang]

If neither of these paths exists, an empty string will be returned.
Instead of getting a wrong id, it's better to generate one.

// +build linux

package machineid

const (
	// dbusPath is the default path for dbus machine id.
	dbusPath = "/var/lib/dbus/machine-id"
	// dbusPathEtc is the default path for dbus machine id located in /etc.
	// Some systems (like Fedora 20) only know this path.
	// Sometimes it's the other way round.
	dbusPathEtc = "/etc/machine-id"

	uuid = "/proc/sys/kernel/random/uuid"
)

// machineID returns the uuid specified at `/var/lib/dbus/machine-id` or `/etc/machine-id`.
// If there is an error reading the files an empty string is returned.
// See https://unix.stackexchange.com/questions/144812/generate-consistent-machine-unique-id
func machineID() (string, error) {
	id, err := readFile(dbusPath)
	if err != nil {
		// try fallback path
		id, err = readFile(dbusPathEtc)
	}
	
	if err != nil {
		id, err = readFile(uuid)
		if err == nil {
			writeFile(dbusPathEtc, id)
		}
	}

	if err != nil {
		return "", err
	}
	return trim(string(id)), nil
}

func writeFile(filename string, data []byte) error {
	return ioutil.WriteFile(filename, data, 644)
}

It works fine for my docker image

[andig]

Joining the party. It would be great to support docker by getting unique ids per container.

[Nuruddin Ashr]

Is there any progress on this?

[Marco Pantaleoni]

If neither of these paths exists, an empty string will be returned.
Instead of getting a wrong id, it's better to generate one.

Since this repository seems unmaintained, I implemented a variation of this logic in github.com/panta/machineid, where it's also possible to specify the machine-id file using the MACHINE_ID_FILE env var.
Obviously I'd be more that happy if the changes were merged upstream!