Filestream inputs with duplicated ID cause Filebeat to panic

[belimawr]

First things first: having two Filestream inputs configured with the same ID will lead to data duplication, this is not a valid configuration.

• Version: main, 8.9 branch
• Operating System: all

Steps to Reproduce

1. Create a filebeat.yml with the following content

   filebeat:
     inputs:
       - type: filestream
         id: foo
         paths:
           - /tmp/foo
       - type: filestream
         id: foo
         paths:
           - /tmp/foo2
   output:
     file:
       enabled: true

2. Run Filebeat
3. It will panic:

panic: name foo already used

goroutine 90 [running]:
github.com/elastic/elastic-agent-libs/monitoring.panicErr(...)
        /home/tiago/go/pkg/mod/github.com/elastic/elastic-agent-libs@v0.3.9/monitoring/registry.go:257
github.com/elastic/elastic-agent-libs/monitoring.(*Registry).Add(0xc0003a9840, {0xc0003a46b8, 0x0}, {0x45f3b60, 0xc00072d380}, 0x30)
        /home/tiago/go/pkg/mod/github.com/elastic/elastic-agent-libs@v0.3.9/monitoring/registry.go:155 +0xda
github.com/elastic/elastic-agent-libs/monitoring.(*Registry).NewRegistry(0xc0003a9840, {0xc0003a46b8, 0x3}, {0x0?, 0x0?, 0x4078f36?})
        /home/tiago/go/pkg/mod/github.com/elastic/elastic-agent-libs@v0.3.9/monitoring/registry.go:94 +0x165
github.com/elastic/beats/v7/libbeat/monitoring/inputmon.NewInputRegistry({0x407584e, 0xa}, {0xc0003a46b8, 0x3}, 0xc00013bb10?)
        /home/tiago/devel/beats/libbeat/monitoring/inputmon/input.go:64 +0x3e6
github.com/elastic/beats/v7/filebeat/input/filestream/internal/input-logfile.NewMetrics({0xc0003a46b8, 0x3})
        /home/tiago/devel/beats/filebeat/input/filestream/internal/input-logfile/metrics.go:66 +0xa5
github.com/elastic/beats/v7/filebeat/input/filestream/internal/input-logfile.(*managedInput).Run(_, {0xc000488c30, {0xc0003a46b8, 0x3}, {{0x40708ec, 0x8}, {0x40708ec, 0x8}, {0x406b23e, 0x6}, ...}, ...}, ...)
        /home/tiago/devel/beats/filebeat/input/filestream/internal/input-logfile/input.go:64 +0x1bd
github.com/elastic/beats/v7/filebeat/input/v2/compat.(*runner).Start.func1()
        /home/tiago/devel/beats/filebeat/input/v2/compat/compat.go:122 +0x215
created by github.com/elastic/beats/v7/filebeat/input/v2/compat.(*runner).Start
        /home/tiago/devel/beats/filebeat/input/v2/compat/compat.go:119 +0xd8

The problem comes from registering metrics for Filestream inputs using the ID:

beats/filebeat/input/filestream/internal/input-logfile/metrics.go

Line 66 in 59447f6

reg, unreg := inputmon.NewInputRegistry("filestream", id, nil)

when the second input tries to registry its metrics, the monitoring/metrics code panics.

We need to find a way to detect this case and prevent the panic from happening.

[botelastic]

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