apache/pulsar · critical

config file is nil.

Error message

config file is nil.

What it means

newInstanceConf builds the Go function instance configuration from a YAML config file. If conf.GetConf() returns nil (viper failed to read/parse the config), the code panics with 'config file is nil.' because the instance cannot run without its configuration.

Source

Thrown at pulsar-function-go/pf/instanceConf.go:158

	if !instanceConf.funcDetails.AutoAck && //nolint:staticcheck
		(instanceConf.funcDetails.ProcessingGuarantees == pb.ProcessingGuarantees_ATMOST_ONCE ||
			instanceConf.funcDetails.ProcessingGuarantees == pb.ProcessingGuarantees_ATLEAST_ONCE) {
		panic("When Guarantees == " + instanceConf.funcDetails.ProcessingGuarantees.String() +
			", autoAck must be equal to true. If you want not to automatically ack, " +
			"please configure the processing guarantees as MANUAL." +
			" This is a contradictory configuration, autoAck will be removed later." +
			" Please refer to PIP: https://github.com/apache/pulsar/issues/15560")
	}

	return instanceConf
}

func newInstanceConf() *instanceConf {
	config := &conf.Conf{}
	cfg := config.GetConf()
	if cfg == nil {
		panic("config file is nil.")
	}
	return newInstanceConfWithConf(cfg)
}

func (ic *instanceConf) getInstanceName() string {
	return "" + fmt.Sprintf("%d", ic.instanceID)
}

View on GitHub (pinned to 820761864e)

Solutions

1. Ensure the config file path passed to the instance exists and is valid YAML before starting the function
2. Verify environment variables/config injected by the runtime (e.g. conf file at /etc/pulsar/functions/config) are mounted
3. Add a pre-flight check: load conf.Conf{}.GetConf() yourself and log viper errors instead of hitting the panic
4. When running tests, construct the conf explicitly rather than relying on the default file lookup

Example fix

// before
ctx := pf.NewFuncContext() // panics: config file is nil.
// after
if cfg := (&conf.Conf{}).GetConf(); cfg == nil {
    log.Fatal("instance config missing: pass a valid config file path")
}
ctx := pf.NewFuncContext()

cfg := (&conf.Conf{}).GetConf()
if cfg == nil {
    return fmt.Errorf("instance config file missing or invalid")
}

func hasConfig() bool { return (&conf.Conf{}).GetConf() != nil }

// Go panics are not catchable idiomatic; pre-validate instead.
// If necessary: defer func() { if r := recover(); r != nil { log.Fatalf("config load failed: %v", r) } }()

When it happens

Trigger: Calling pf.NewFuncContext (which calls newInstanceConf) when the config file path is wrong, the file does not exist, it is malformed YAML, or the environment (e.g. kubeless/function-mesh injector) failed to mount it.

Common situations: Running a Go function locally without the config file that production injects (functions_instance_config.conf), bad func.yaml config path, missing --instance-conf argument, or a k8s ConfigMap/volume mount miss.

Related errors

• start function failed, please check.
• function is nil
• function kind %s is not %s
• Failed to unmarshal consume specs: %v
• Functions Worker Service Nar Package `${name}` does NOT prov

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/0230b5ada888cb45. Report an issue: GitHub.