add prometheus exporter for minecraft

[CasparChou]

add prometheus exporter for minecraft

visualization game stats and jvm memory usage

by using Prometheus Operator (optional) and Prometheus Exporter Plugins (https://dev.bukkit.org/projects/prometheus-exporter)

[CasparChou]

@itzg don't know how to fix lint-test failed... is there any more detail logs can check ?

[itzg]

Great contribution; however, I would prefer that it incorporate

https://github.com/itzg/mc-monitor

using its Prometheus exporter mode since that will work for all server types without any additional plugin.

[CasparChou]

mc-monitor seems cool !
maybe I can try to add this to chart

[itzg]

Let me know if it looks like it'll be too hard to add mc-monitor and the changes you have will be an excellent step in that direction.

[CasparChou]

do you prefer to add a chart mc-monitor inside this repo, or just add a sidecar beside the minecraft-server container ?

[itzg]

Since mc-monitor doesn't know how to do service discovery, then deploying as a side car makes more sense.

[CasparChou]

itzg/mc-monitor crash after pod started, but it works when I run the code by go run, still troubleshooting

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0x7e1787]
goroutine 14 [running]:
main.(*promBedrockCollector).Collect(0xc000099a40, 0xc000172300)
/home/circleci/project/prom_collector.go:159 +0x357
main.promCollectors.Collect(0xc0000ad9c0, 0x2, 0x2, 0xc000172300)
/home/circleci/project/prom_collector.go:51 +0x64
github.com/prometheus/client_golang/prometheus.(*Registry).Gather.func1()
/go/pkg/mod/github.com/prometheus/[email protected]/prometheus/registry.go:443 +0x19d
created by github.com/prometheus/client_golang/prometheus.(*Registry).Gather
/go/pkg/mod/github.com/prometheus/[email protected]/prometheus/registry.go:535 +0xe36

it said prom_collector.go:L159 has a null pointer error
the problem maybe is mc server not ready

[itzg]

Oh yeah, that might be an edge case that the code isn't handling well. I'll try to look at that today.

If I can get to that soon we can go with your original plan and then use a separate PR to add mc-monitor.

[itzg]

Even IntelliJ is warning me just by it looking at the code :)

[CasparChou]

lol. glad to find out the potential error

[itzg]

0.6.1 now includes the fix

[ChipWolf]

@CasparChou are you wanting to continue with this? Happy to take over if not

[caseyjmorton]

FYI to all interested in this, I'm going to resume work on this as part of my work on a minecraft-operator. Most of the operator code is based on these helm charts, so I'm happy to do any maintenance needed. That said, since this PR is almost 3 years old, I'm sure there has been plenty of drift and rather than try to resolve the conflicts, I'm just going to submit a totally new PR. Once filed, I will post a link to the new one here, for posterity.