Prometheus Relabel Config Examples - https://prometheus.io/docs/operating/configuration/#<relabel_config>

prometheus.yml

global:
  scrape_interval: 60s

  external_labels:
    monitor: 'example'

rule_files:
  - /etc/prometheus/config/*.rules

scrape_configs:

  - job_name: 'scrape-then-use-relabel-to-rename-selected-metrics'
    static_configs:
      - targets: ['10.10.10.1:19126']
    metric_relabel_configs:
      - source_labels: [ __name__ ]
        target_label: __name__
        regex: '(^(?:go|http|process)_.*$)'
        action: replace
        replacement: telegraf_${1}

  - job_name: 'scrape-then-use-relabel-to-remove-a-label'
    static_configs:
      - targets: ['10.10.10.2:19126']
    metric_relabel_configs:
      - source_labels: [ host ]
        target_label: host
        action: replace
        replacement: ''
        
  - job_name: 'scrape-then-use-relabel-add-an-arbitrary-label'
    static_configs:
      - targets: ['10.10.10.3:19126']
    metric_relabel_configs:
     - source_labels: [ instance ]
       target_label: instance
       action: replace
       replacement: log-downloader