SNMPv2 Expansion of Environment Variables

[IvoGoman]

Host operating system: output of uname -a

snmp_exporter version: output of snmp_exporter -version

current head version

What device/snmpwalk OID are you using?

not relevant

If this is a new device, please link to the MIB(s).

not relevant

What did you do that produced an error?

We are using a mix of SNMPv2 and SNMPv3 in the auth.yaml. With one device not configured with auth settings.

acistretch_v2:
  version: 2
  community: bla

This v2 module does not work as expected when using expansion of environment variables.
ts=2024-03-27T13:28:01.053Z caller=main.go:203 level=error msg="Error parsing config file" err=" environment variable not found"

The error seems to be here:

snmp_exporter/config/config.go

Lines 47 to 65 in 733e5a1

	if expandEnvVars {
	var err error
	for i, auth := range cfg.Auths {
	cfg.Auths[i].Username, err = substituteEnvVariables(auth.Username)
	if err != nil {
	return nil, err
	}
	password, err := substituteEnvVariables(string(auth.Password))
	if err != nil {
	return nil, err
	}
	cfg.Auths[i].Password.Set(password)
	privPassword, err := substituteEnvVariables(string(auth.PrivPassword))
	if err != nil {
	return nil, err
	}
	cfg.Auths[i].PrivPassword.Set(privPassword)
	}
	}

Since the v2 configuration has no username, password or privPassword this expansion of env variables fails.

Introduced by 59194f6

What did you expect to see?

snmp-exporter does not fail parsing the env variables

What did you see instead?

the above mentionend error message