[inputs.procstat] systemd_unit is no longer working after #13417

[tjnome]

Relevant telegraf.conf

[[inputs.procstat]]
  systemd_unit = "crond.service"

Logs from Telegraf

telegraf --test --debug --config /tmp/test.conf 

2023-12-12T10:25:55Z I! Loading config: /tmp/test.conf
2023-12-12T10:25:55Z E! error loading config file /tmp/test.conf: plugin inputs.procstat: line 1: configuration specified the fields ["systemd_unit"], but they weren't used

System info

Telegraf 1.29.0

Docker

No response

Steps to reproduce

1. Use old config from before 1.29.0 update or follow README doc https://github.com/influxdata/telegraf/blob/master/plugins/inputs/procstat/README.md

...

Expected behavior

The intended behavior should be metrics. However, due to modifications in the TOML configuration, it no longer searches for 'systemd_unit' but rather 'systemd_units' and old configuration fails

Actual behavior

2023-12-12T10:25:55Z E! error loading config file /tmp/test.conf: plugin inputs.procstat: line 1: configuration specified the fields ["systemd_unit"], but they weren't used

Additional info

This is a straightforward bug that testing should have identified. To ensure 'input.procstat' functions correctly in version 1.29.0, the configuration must be altered from 'systemd_unit' to 'systemd_units'. This change appears to be unexpected and likely an oversight.

[poulhs]

Influx data support case Number: 00115464

[srebhan]

@tjnome, @poulhs and @hackery first of all sorry for breaking your configs! Can you please check the binary in PR #14440 available once CI finished the tests!? Let me know if this fixes the issue!

[tjnome]

No problem. I have tested the RP on RHEL[7-9] and works flawlessly. @srebhan

[poulhs]

works fine for me too:

• /usr/bin/telegraf --version
  Telegraf 1.30.0-bfe2033b (git: pull/14440@bfe2033b)
• /usr/bin/telegraf --test --config inputs_procstat_crond.conf
  2023-12-12T13:29:32Z I! Loading config: inputs_procstat_crond.conf
  2023-12-12T13:29:32Z I! Starting Telegraf 1.30.0-bfe2033b brought to you by InfluxData the makers of InfluxDB
  2023-12-12T13:29:32Z I! Available plugins: 241 inputs, 9 aggregators, 30 processors, 24 parsers, 60 outputs, 6 secret-stores
  2023-12-12T13:29:32Z I! Loaded inputs: procstat
  2023-12-12T13:29:32Z I! Loaded aggregators:
  2023-12-12T13:29:32Z I! Loaded processors:
  2023-12-12T13:29:32Z I! Loaded secretstores:
  2023-12-12T13:29:32Z W! Outputs are not used in testing mode!
  2023-12-12T13:29:32Z I! Tags enabled: host=hostname.elided

procstat,host=hostname.elided,process_name=crond,systemd_unit=crond.service child_major_faults=80i,child_minor_faults=10829757i,cmdline="/usr/sbin/crond -n",cpu_time=2i,cpu_time_iowait=0,cpu_time_system=2.05,cpu_time_user=0.38,cpu_usage=0,created_at=1701660895000000000i,involuntary_context_switches=269i,major_faults=2i,memory_anonymous=868i,memory_data=847872i,memory_locked=0i,memory_private_clean=64i,memory_private_dirty=868i,memory_pss=1032i,memory_referenced=3660i,memory_rss=3747840i,memory_shared_clean=2728i,memory_shared_dirty=0i,memory_size=0i,memory_stack=532480i,memory_swap=0i,memory_usage=0.09865377843379974,memory_vms=8749056i,minor_faults=10082i,nice_priority=20i,num_fds=6i,num_threads=1i,pid=1683i,ppid=1i,read_bytes=49033216i,read_count=16448201i,realtime_priority=0i,rlimit_cpu_time_hard=9223372036854775807i,rlimit_cpu_time_soft=9223372036854775807i,rlimit_file_locks_hard=9223372036854775807i,rlimit_file_locks_soft=9223372036854775807i,rlimit_memory_data_hard=9223372036854775807i,rlimit_memory_data_soft=9223372036854775807i,rlimit_memory_locked_hard=8388608i,rlimit_memory_locked_soft=8388608i,rlimit_memory_rss_hard=9223372036854775807i,rlimit_memory_rss_soft=9223372036854775807i,rlimit_memory_stack_hard=9223372036854775807i,rlimit_memory_stack_soft=8388608i,rlimit_memory_vms_hard=9223372036854775807i,rlimit_memory_vms_soft=9223372036854775807i,rlimit_nice_priority_hard=0i,rlimit_nice_priority_soft=0i,rlimit_num_fds_hard=524288i,rlimit_num_fds_soft=1024i,rlimit_realtime_priority_hard=0i,rlimit_realtime_priority_soft=0i,rlimit_signals_pending_hard=14333i,rlimit_signals_pending_soft=14333i,signals_pending=0i,status="sleep",user="root",voluntary_context_switches=12527i,write_bytes=12580835328i,write_count=4152596i 1702387773000000000
procstat_lookup,host=hostname.elided,pid_finder=pgrep,result=success pid_count=1i,result_code=0i,running=1i 1702387773000000000

• : status=0

[hackery]

Thanks @srebhan - we won't be taking the PR binary for production use, but it looks like it'll land in 1.29.1, we'll take that when it releases.