prometheus_scrape can't handle label values with more than 1024 characters

[MartinGers]

Bug Report

Describe the bug
If an opentelemetry-contrib prometheus exporter exposes the mandatory target_info metric with a very long process_command line label, the prometheus scrape plugin neither collect any of the exposed metrics nor it throws any error or warning.

To Reproduce
Try to scrape the following metric with the fluent-bit prometheus_scrape plugin.
target_info{process_command_line="foobaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaar"} 1
If one character will be removed, the the scrape plugin can process the metric.

Expected behavior
Should handle label values longer than 1024 characters. Maybe the label value size should be configurable? For debugging reasons, a message should be logged, what happens in detail.

Your Environment

• Version used: 3.1.6
• Configuration:

[INPUT]
    Name                prometheus_scrape
    Host                0.0.0.0
    Port                9200
    Metrics_Path        /metrics
    Scrape_Interval     5s
    Buffer_Max_Size     100MB


[OUTPUT]
    name stdout
    match *

• Operating System and version: Linux
• Filters and plugins: prometheus_scrape plugin

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[github-actions]

This issue was closed because it has been stalled for 5 days with no activity.