txthinking/brook · error

--blockCIDR6List must be with absolute path

Error message

--blockCIDR6List must be with absolute path

What it means

This is a CLI startup validation guard in the brook command: when --blockCIDR6List is given as a relative filesystem path the command refuses to start, because the block list file must be addressable unambiguously regardless of the working directory (the same pattern also allows http:// or https:// URLs). The input at fault is a relative --blockCIDR6List value; pass an absolute path (or an http(s) URL).

Source

Thrown at cli/brook/main.go:273

			p := prometheus.NewPrometheus(c.String("prometheus"), c.String("prometheusPath"), m)
			p.TouchBrook()
			g.Add(&runnergroup.Runner{
				Start: func() error {
					return p.ListenAndServe()
				},
				Stop: func() error {
					return p.Shutdown()
				},
			})
		}
		if c.String("blockDomainList") != "" && !strings.HasPrefix(c.String("blockDomainList"), "http://") && !strings.HasPrefix(c.String("blockDomainList"), "https://") && !filepath.IsAbs(c.String("blockDomainList")) {
			return errors.New("--blockDomainList must be with absolute path")
		}
		if c.String("blockCIDR4List") != "" && !strings.HasPrefix(c.String("blockCIDR4List"), "http://") && !strings.HasPrefix(c.String("blockCIDR4List"), "https://") && !filepath.IsAbs(c.String("blockCIDR4List")) {
			return errors.New("--blockCIDR4List must be with absolute path")
		}
		if c.String("blockCIDR6List") != "" && !strings.HasPrefix(c.String("blockCIDR6List"), "http://") && !strings.HasPrefix(c.String("blockCIDR6List"), "https://") && !filepath.IsAbs(c.String("blockCIDR6List")) {
			return errors.New("--blockCIDR6List must be with absolute path")
		}
		if c.String("blockDomainList") != "" || c.String("blockCIDR4List") != "" || c.String("blockCIDR6List") != "" || len(c.StringSlice("blockGeoIP")) != 0 {
			p, err := block.NewBlock(c.String("blockDomainList"), c.String("blockCIDR4List"), c.String("blockCIDR6List"), c.StringSlice("blockGeoIP"), c.Int("blockListUpdateInterval"))
			if err != nil {
				return err
			}
			p.TouchBrook()
			if c.Int("blockListUpdateInterval") != 0 {
				g.Add(&runnergroup.Runner{
					Start: func() error {
						p.Update()
						return nil
					},
					Stop: func() error {
						p.Stop()
						return nil
					},
				})

View on GitHub (pinned to 5cd13ef3b1)

Solutions

1. Use an absolute path: --blockCIDR6List /etc/brook/cidr6.txt
2. Use an http(s) URL for the list
3. Make the launch script emit absolute paths

Example fix

// before
brook server -l :9999 --blockCIDR6List cidr6.txt
// after
brook server -l :9999 --blockCIDR6List /etc/brook/cidr6.txt

if v := blockCIDR6List; v != "" && !strings.HasPrefix(v, "http://") && !strings.HasPrefix(v, "https://") && !filepath.IsAbs(v) {
	return fmt.Errorf("--blockCIDR6List must be URL or absolute path, got %q", v)
}

When it happens

Trigger: --blockCIDR6List cidr6.txt or another relative path lacking an http(s):// prefix while non-empty.

Common situations: Relative paths in compose/unit files; forgetting the scheme for hosted lists; mismatch between dev and production working directories.

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

• --blockDomainList must be with absolute path
• --blockCIDR4List must be with absolute path
• --pid must be with absolute path
• --log must be with absolute path
• --cert must be with absolute path

AI-assisted analysis of txthinking/brook@5cd13ef3b1 (2026-09-06). Data as JSON: /api/errors/b8d1f1fb35a64897. Report an issue: GitHub.