Custom object template - panic if counter list item indent differs

[mamoep]

Describe the bug
I tried to create a custom object template via ansible with {{ item | to_nice_yaml(indent=2) }}. The generated output is valid yaml, but the list items under counter: are not indented as documented for harvest.

Example template (failing):

name: NetPort
object: net_port
query: net-port-get-iter
counters:
  net-port-info:
  - ^broadcast-domain => broadcast_domain
  - ^ifgrp-distribution-function => ifgrp_dist_func
  - ^ifgrp-mode => ifgrp_mode
  - ^ifgrp-port => ifgrp_port
  - ^is-administrative-up => admin_up
  - ^link-status => link_status
  - ^^node => node
  - ^operational-duplex => op_duplex
  - ^operational-speed => op_speed
  - ^^port => port
  - ^port-type => port_type
  - ^role => role
  - ^vlan-id => vlan_id
  - ^vlan-node => vlan_node
  - ^vlan-port => vlan_port
collect_only_labels: true
export_options:
  include_all_labels: true
plugins:
  LabelAgent:
    value_to_num: status link_status up up `0`

Example template (working):

name:   NetPort
query:  net-port-get-iter
object: net_port
counters:
  net-port-info:
    - ^broadcast-domain => broadcast_domain
    - ^ifgrp-distribution-function => ifgrp_dist_func
    - ^ifgrp-mode => ifgrp_mode
    - ^ifgrp-port => ifgrp_port
    - ^is-administrative-up => admin_up
    - ^link-status => link_status
    - ^^node => node
    - ^operational-duplex => op_duplex
    - ^operational-speed => op_speed
    - ^^port => port
    - ^port-type => port_type
    - ^role => role
    - ^vlan-id => vlan_id
    - ^vlan-node => vlan_node
    - ^vlan-port => vlan_port
collect_only_labels: true
plugins:
  LabelAgent:
    value_to_num: status link_status up up `0`
export_options:
  include_all_labels: true

Environment
Provide accurate information about the environment to help us reproduce the issue.

• Harvest version: harvest version 21.11.0-1 (commit 66c5ce1) (build date 2021-11-08T08:32:01-0500) linux/amd64
• Command line arguments used: bin/harvest start
• OS: RHEL 7.9
• Install method: rhel

To Reproduce
Steps to reproduce the behavior:
define custom template as described above

Expected behavior
Collect defined custom metrics

Actual behavior
Template is not picked up and metrics dont get collected

Possible solution, workaround, fix
Indent counter list entries.

Additional context
Log output

"level":"error","Poller":"clustername","collector":"Zapi:NetPort",
  "stack":[
    {"func":"New","line":"35","source":"errors.go"},
    {"func":"(*AbstractCollector).Start.func1","line":"259","source":"collector.go"},
    {"func":"gopanic","line":"1038","source":"panic.go"},
    {"func":"goPanicIndex","line":"90","source":"panic.go"},
    {"func":"(*Node).SearchChildren.func1","line":"438","source":"node.go"},
    {"func":"(*Node).SearchChildren","line":"452","source":"node.go"},
    {"func":"(*Zapi).PollInstance","line":"268","source":"zapi.go"},
    {"func":"(*task).Run","line":"61","source":"schedule.go"},
    {"func":"(*AbstractCollector).Start","line":"293","source":"collector.go"},
    {"func":"goexit","line":"1581","source":"asm_amd64.s"}
    ],
  "error":"goroutine panic => goroutine 504 [running]:\n
    runtime/debug.Stack()\n\t
    runtime/debug/stack.go:24 +0x65\ngoharvest2/cmd/poller/collector.(*AbstractCollector).Start.func1()\n\t
    goharvest2/cmd/poller/collector/collector.go:259 +0x85\n
    panic({0x98e6c0, 0xc0004be5b8})\n\t
    runtime/panic.go:1038 +0x215\n
    goharvest2/pkg/tree/node.(*Node).SearchChildren.func1(0xc000c79290, {0xe44d78, 0x0, 0x0})\n\t
    goharvest2/pkg/tree/node/node.go:438 +0x485\ngoharvest2/pkg/tree/node.(*Node).SearchChildren(0x9b2240, {0xe44d78, 0x0, 0x0})\n\t
    goharvest2/pkg/tree/node/node.go:452 +0xd9\ngoharvest2/cmd/collectors/zapi/collector.(*Zapi).PollInstance(0xc00012f400)\n\t
    goharvest2/cmd/collectors/zapi/collector/zapi.go:268 +0x4e5\n
    goharvest2/cmd/poller/schedule.(*task).Run(0xc0001f22d0)\n\t
    goharvest2/cmd/poller/schedule/schedule.go:61 +0x4e\n
    goharvest2/cmd/poller/collector.(*AbstractCollector).Start(0xc0000f4b60, 0xe13d50)\n\t
    goharvest2/cmd/poller/collector/collector.go:293 +0x40a\n
    created by main.(*Poller).Start\n\t
    ./poller.go:394 +0x2e5\n",
  "caller":"goharvest2/cmd/poller/collector/collector.go:259",
  "time":"2021-11-26T10:32:23+01:00",
  "message":"Collector panicked runtime error: index out of range [0] with length 0"

[rahulguptajss]

@mamoep Thanks for reporting it. We are aware of this issue. We'll look into solving it.

[cgrinds]

Verified using mamoep included failing netport.yaml. Poller starts and collects without error.
Verified on release/22.02.0 3d038fe

bin/harvest start u2 --foreground --collectors Zapi --objects NetPort
starting in foreground, enter CTRL+C or close terminal to stop poller
2:26PM INF ./poller.go:182 > log level used: info Poller=u2
2:26PM INF ./poller.go:183 > options config: ./harvest.yml Poller=u2
2:26PM INF ./poller.go:220 > started in foreground [pid=84870] Poller=u2
2:26PM INF goharvest2/cmd/poller/collector/helpers.go:122 > best-fit template [conf/zapi/cdot/9.8.0/netport.yaml] for [9.7.0] Poller=u2 collector=Zapi:NetPort
2:26PM INF ./poller.go:344 > Autosupport scheduled. Poller=u2 asupSchedule=24h
2:26PM INF ./poller.go:353 > poller start-up complete Poller=u2
2:26PM INF ./poller.go:501 > updated status, up collectors: 1 (of 1), up exporters: 1 (of 1) Poller=u2