Function GenerateRandomID

daemon/internal/stringid/stringid.go:40–60

GenerateRandomID returns a unique, 64-character ID consisting of a-z, 0-9. It guarantees that the ID, when truncated ([TruncateID]) does not consist of numbers only, so that the truncated ID can be used as hostname for containers.

()

// of numbers only, so that the truncated ID can be used as hostname for
// containers.
func GenerateRandomID() string {
	b := make([]byte, 32)
	for {
		if _, err := rand.Read(b); err != nil {
			panic(err) // This shouldn't happen
		}
		id := hex.EncodeToString(b)

		// make sure that the truncated ID does not consist of only numeric
		// characters, as it's used as default hostname for containers.
		//
		// See:
		// - https://github.com/moby/moby/issues/3869
		// - https://bugzilla.redhat.com/show_bug.cgi?id=1059122
		if allNum(id[:shortLen]) {
			// all numbers; try again
			continue
		}
		return id
	}
}

// allNum checks whether id consists of only numbers (0-9).
func allNum(id string) bool {