hashicorp/nomad · error

Job datacenter must be non-empty string

Error message

Job datacenter must be non-empty string

What it means

When j.Datacenters is non-empty, Job.Validate() iterates the list and rejects any empty-string entry. Every datacenter name must be a non-empty string so the scheduler can match it against node datacenter labels.

Source

Thrown at nomad/structs/structs.go:4771

		mErr.Errors = append(mErr.Errors, errors.New("Job Name contains a null character"))
	}

	if j.Namespace == "" {
		mErr.Errors = append(mErr.Errors, errors.New("Job must be in a namespace"))
	}
	switch j.Type {
	case JobTypeCore, JobTypeService, JobTypeBatch, JobTypeSystem, JobTypeSysBatch:
	case "":
		mErr.Errors = append(mErr.Errors, errors.New("Missing job type"))
	default:
		mErr.Errors = append(mErr.Errors, fmt.Errorf("Invalid job type: %q", j.Type))
	}
	if len(j.Datacenters) == 0 && !j.IsMultiregion() {
		mErr.Errors = append(mErr.Errors, errors.New("Missing job datacenters"))
	} else {
		for _, v := range j.Datacenters {
			if v == "" {
				mErr.Errors = append(mErr.Errors, errors.New("Job datacenter must be non-empty string"))
			}
		}
	}

	if len(j.TaskGroups) == 0 {
		mErr.Errors = append(mErr.Errors, errors.New("Missing job task groups"))
	}
	for idx, constr := range j.Constraints {
		if err := constr.Validate(); err != nil {
			outer := fmt.Errorf("Constraint %d validation failed: %s", idx+1, err)
			mErr.Errors = append(mErr.Errors, outer)
		}
	}
	if j.Type == JobTypeSystem {
		if j.Affinities != nil {
			mErr.Errors = append(mErr.Errors, fmt.Errorf("System jobs may not have an affinity block"))
		}
	} else {

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Remove empty entries from the datacenters list, keeping only valid names
2. Fix the template/variable that renders empty and add a non-empty guard
3. Filter with a helper before submission (keep only trimmed non-empty values)

Example fix

// before
datacenters = ["dc1", "${extra_dc}"]
// after
datacenters = ["dc1"]
// or ensure ${extra_dc} resolves to a real datacenter name

cleaned := make([]string, 0, len(j.Datacenters))
for _, dc := range j.Datacenters {
    if strings.TrimSpace(dc) != "" { cleaned = append(cleaned, dc) }
}
j.Datacenters = cleaned

func hasValidDatacenters(dcs []string) bool {
    for _, dc := range dcs { if strings.TrimSpace(dc) == "" { return false } }
    return len(dcs) > 0
}

if err := job.Validate(); err != nil {
    if strings.Contains(err.Error(), "datacenter must be non-empty") {
        return fmt.Errorf("remove empty entries from the datacenters list: %w", err)
    }
}

When it happens

Trigger: Submitting a job with datacenters = ["dc1", ""] or with a template variable that renders empty inside the list; constructing structs.Job with an empty-string element in Datacenters.

Common situations: Templating like datacenters = ["${dc}"] where ${dc} resolves to ""; trailing commas or whitespace-only entries after string processing; merging config files that append an empty entry.

Related errors

• Missing job datacenters
• Missing job ID
• Job ID contains a space
• Job ID contains a null character
• Missing job name

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/9679ca9bfd105597. Report an issue: GitHub.