abiosoft/colima · critical

error parsing disk mount script template: %v

Error message

error parsing disk mount script template: %v

What it means

diskMountScript (environment/vm/lima/disk.go:107) parses the hardcoded diskScript template with a fixed values struct {Format bool, InstanceId string}; if ParseTemplate returns any error it panics with this message ('must never happen'). Because both the template body and the values are compile-time constants in the same file, the only way to reach the panic is a source edit that breaks the template (syntax error) or references a field absent from the values struct. It crashes the CLI at VM startup whenever a runtime disk is provisioned.

Source

Thrown at environment/vm/lima/disk.go:107

		return incus.DataDisk()
	}

	return environment.DataDisk{}
}

func diskMountScript(format bool) string {
	var values = struct {
		Format     bool
		InstanceId string
	}{
		Format:     format,
		InstanceId: config.CurrentProfile().ID,
	}

	b, err := util.ParseTemplate(diskScript, values)
	if err != nil {
		// must never happen
		panic(fmt.Sprintf("error parsing disk mount script template: %v", err))
	}
	return string(b)
}

func (l *limaVM) mountRuntimeDisk(conf config.Config, format bool) {
	// provision script to prepare disk
	l.limaConf.Provision = append(l.limaConf.Provision, limaconfig.Provision{
		Mode:   "dependency",
		Script: diskMountScript(format),
	})

	// handle disk mounts
	disk := dataDisk(conf.Runtime)

	// pre mount script
	for _, script := range disk.PreMount {
		l.limaConf.Provision = append(l.limaConf.Provision, limaconfig.Provision{
			Mode:   "dependency",

View on GitHub (pinned to c3a5f9184d)

Solutions

1. Fix the template literal in disk.go: match field names exactly (Format, InstanceId) and balance delimiters
2. Add a unit test that calls diskMountScript(true) and diskMountScript(false) and asserts no panic and non-empty output
3. Run `go test ./environment/...` after touching templates before starting a VM
4. If hit on a stock binary, reinstall — it means the binary does not match the sources

Example fix

// environment/vm/lima/disk.go (before)
const diskScript = `echo {{.format}} {{.InstanceId}}` // .format -> execute error -> panic

// after
const diskScript = `echo {{.Format}} {{.InstanceId}}`

// fork safety net: validate the disk template at init/test time
func init() {
    if _, err := util.ParseTemplate(diskScript, struct {
        Format     bool
        InstanceId string
    }{true, "test"}); err != nil {
        panic("diskScript template is broken: " + err.Error())
    }
}

// if you call code that may panic during template generation:
defer func() {
    if r := recover(); r != nil {
        return fmt.Errorf("disk mount script generation failed: %v", r)
    }
}()

When it happens

Trigger: Editing the diskScript template literal in environment/vm/lima/disk.go and introducing a typo ({{.format}} instead of {{.Format}}, missing braces), then running `colima start` with a disk configured — the panic fires while generating the Lima provision script.

Common situations: Fork development around disk mounting; renaming config fields without updating the template; build from a dirty tree mid-refactor.

Related errors

• error deleting container data: %w
• error creating runtime disk: %w
• dependency check failed for VM: %w
• error starting vm: %w
• error stopping vm: %w

AI-assisted analysis of abiosoft/colima@c3a5f9184d (2026-08-15). Data as JSON: /api/errors/4429266797963913. Report an issue: GitHub.