hashicorp/nomad · error · ErrCgroupMustBeSet

configureCgroups: %w

Error message

configureCgroups: %w

What it means

configureCgroups (called from newLibcontainerConfig) returns early if ResourceLimits is off; otherwise it requires a stats cgroup name from command.StatsCgroup(). When the cgroup is empty it wraps the sentinel ErrCgroupMustBeSet with this "configureCgroups: " prefix. It means the executor cannot place the task into a cgroup because none was assigned by the driver/client.

Source

Thrown at drivers/shared/executor/executor_linux_cgo.go:782

	}

	if len(command.Mounts) > 0 {
		cfg.Mounts = append(cfg.Mounts, cmdMounts(command.Mounts)...)
	}

	return nil
}

func (l *LibcontainerExecutor) configureCgroups(cfg *runc.Config, command *ExecCommand) error {
	// note: an alloc TR hook pre-creates the cgroup(s) in both v1 and v2

	if !command.ResourceLimits {
		return nil
	}

	cg := command.StatsCgroup()
	if cg == "" {
		return fmt.Errorf("configureCgroups: %w", ErrCgroupMustBeSet)
	}

	// // set the libcontainer hook for writing the PID to cgroup.procs file
	// TODO: this can be cg1 only, right?
	// l.configureCgroupHook(cfg, command)

	// set the libcontainer memory limits
	l.configureCgroupMemory(cfg, command)

	// set cgroup v1/v2 specific attributes (cpu, path)
	switch cgroupslib.GetMode() {
	case cgroupslib.CG1:
		return l.configureCG1(cfg, command, cg)
	default:
		return l.configureCG2(cfg, command, cg)
	}
}

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Ensure the driver allocates and sets the stats cgroup (SetStatsCgroup) before enabling ResourceLimits and calling Launch
2. Check client cgroup configuration (cgroups v1/v2 setup, nomad cgroup parent) so cgroup allocation succeeds
3. If cgroups are not wanted, disable ResourceLimits in the ExecCommand instead of leaving the cgroup unset
4. Report/fix driver ordering: the cgroup must exist before newLibcontainerConfig runs

if cmd.ResourceLimits && cmd.StatsCgroup() == "" {
    return fmt.Errorf("stats cgroup must be set before Launch when ResourceLimits is enabled")
}

if _, err := executor.Launch(cmd); err != nil && strings.Contains(err.Error(), "configureCgroups") && errors.Is(err, executor.ErrCgroupMustBeSet) {
    log.Printf("stats cgroup missing: %v — set cgroup before Launch", err)
}

When it happens

Trigger: command.ResourceLimits is true but command.StopsCgroup()/StatsCgroup() returns "" — the driver never called SetStatsCgroup / the cgroup was not allocated for the task before Launch.

Common situations: Driver invoked the executor with ResourceLimits enabled but forgot to assign the stats cgroup (driver bug or ordering issue); cgroup allocation failed silently upstream (cgroups v1/v2 misconfiguration on the client); custom code constructing ExecCommand manually without StatsCgroup.

Related errors

• failed to configure container(%s): %v
• error setting up exec subcommand: %w
• ErrCgroupMustBeSet
• unable to get orphaned task PIDs: %v
• unable to send signal to process %d: %v

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/144fb1dc1d85afc9. Report an issue: GitHub.