Specifying --config.file=~/snmp_exporter/generator/snmp.yml does not work

[BYT3M3]

Host operating system: output of uname -a

Linux prometheus-01 5.10.0-11-amd64 #1 SMP Debian 5.10.92-1 (2022-01-18) x86_64 GNU/Linux

snmp_exporter version: output of snmp_exporter --version

snmp_exporter, version 0.25.0 (branch: HEAD, revision: 9c42d6c)

build date:       20231210-10:05:18
go version:       go1.21.5
platform:         linux/amd64
tags:             netgo

What device/snmpwalk OID are you using?

Not applicable

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

Not applicable

What did you do that produced an error?

I tried to generate a minimal snmp.yaml file, so I could just query a sysUpTime.
My generator.yml file looks like:

---
auths:
 public_v1:
   version: 1
 public_v2:
   version: 2

modules:
 # Default IF-MIB interfaces table with ifIndex.
 if_mib:
   walk: [sysUpTime]
   lookups:
     - source_indexes: [ifIndex]
       lookup: ifAlias
     - source_indexes: [ifIndex]
       # Uis OID to avoid conflict with PaloAlto PAN-COMMON-MIB.
       lookup: 1.3.6.1.2.1.2.2.1.2 # ifDescr
     - source_indexes: [ifIndex]
       # Use OID to avoid conflict with Netscaler NS-ROOT-MIB.
       lookup: 1.3.6.1.2.1.31.1.1.1.1 # ifName
   overrides:
     ifAlias:
       ignore: true # Lookup metric
     ifDescr:
       ignore: true # Lookup metric
     ifName:
       ignore: true # Lookup metric
     ifType:
       type: EnumAsInfo

I converted this to snmp.yml using ./generator -g /tmp/generator.yml -o /tmp/snmp.yml and my snmp.yml looks like:

# WARNING: This file was auto-generated using snmp_exporter generator, manual changes will be lost.
auths:
  public_v1:
    community: public
    security_level: noAuthNoPriv
    auth_protocol: MD5
    priv_protocol: DES
    version: 1
  public_v2:
    community: public
    security_level: noAuthNoPriv
    auth_protocol: MD5
    priv_protocol: DES
    version: 2
modules:
  if_mib:
    get:
    - 1.3.6.1.2.1.1.3.0
    metrics:
    - name: sysUpTime
      oid: 1.3.6.1.2.1.1.3
      type: gauge
      help: The time (in hundredths of a second) since the network management portion
        of the system was last re-initialized. - 1.3.6.1.2.1.1.3

What did you expect to see?

When surfing to hostname:9116/config I expect to see:

auths:
  public_v1:
    community: <secret>
    security_level: noAuthNoPriv
    auth_protocol: MD5
    priv_protocol: DES
    version: 1
  public_v2:
    community: <secret>
    security_level: noAuthNoPriv
    auth_protocol: MD5
    priv_protocol: DES
    version: 2
modules:
  if_mib:
    get:
    - 1.3.6.1.2.1.1.3.0
    metrics:
    - name: sysUpTime
      oid: 1.3.6.1.2.1.1.3
      type: gauge
      help: The time (in hundredths of a second) since the network management portion
        of the system was last re-initialized. - 1.3.6.1.2.1.1.3
    max_repetitions: 25
    retries: 3
    timeout: 5s

And when I try to query a machines sysUpTime, I expect to see:

# HELP snmp_scrape_duration_seconds Total SNMP time scrape took (walk and processing).
# TYPE snmp_scrape_duration_seconds gauge
snmp_scrape_duration_seconds{module="if_mib"} 0.002477075
# HELP snmp_scrape_packets_retried Packets retried for get, bulkget, and walk.
# TYPE snmp_scrape_packets_retried gauge
snmp_scrape_packets_retried{module="if_mib"} 0
# HELP snmp_scrape_packets_sent Packets sent for get, bulkget, and walk; including retries.
# TYPE snmp_scrape_packets_sent gauge
snmp_scrape_packets_sent{module="if_mib"} 1
# HELP snmp_scrape_pdus_returned PDUs returned from get, bulkget, and walk.
# TYPE snmp_scrape_pdus_returned gauge
snmp_scrape_pdus_returned{module="if_mib"} 1
# HELP snmp_scrape_walk_duration_seconds Time SNMP walk/bulkwalk took.
# TYPE snmp_scrape_walk_duration_seconds gauge
snmp_scrape_walk_duration_seconds{module="if_mib"} 0.002360924
# HELP sysUpTime The time (in hundredths of a second) since the network management portion of the system was last re-initialized. - 1.3.6.1.2.1.1.3
# TYPE sysUpTime gauge
sysUpTime 9.895252e+06

What did you see instead?

When going to hostname:9116/config I saw:

{}

And querying the ifMib, yielded:

Unknown auth 'public_v2'

How did I work around this issue?

I just replaced ~ (which is the standard reference to the home directory) with an absolute or a relative path and this did work. This issue is a user friendliness bug. This could be fixed by indicating more clearly that the config file wasn't found or even better: just support using ~.