Prometheus relabelling to get rid of port number

gistfile1.txt

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This does what it should:

  regex: (.+?)(:80)?

Also see https://golang.org/pkg/regexp/syntax/

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This returns 'instance="XX"'

      - targets:
        - XX:80
    relabel_configs:
      - source_labels: [ __address__ ]
        target_label: instance
        regex: '(.*):80'
        replacement: '${1}'

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But auto-attached :80 does not go away and results in 'instance="XX:80"'

      - targets:
        - XX
    relabel_configs:
      - source_labels: [ __address__ ]
        target_label: instance
        regex: '(.*):80'
        replacement: '${1}'

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Returns 'instance="XX"'

      - targets:
        - XX
    relabel_configs:
      - source_labels: [ __address__ ]
        target_label: instance
        regex: '(.*)(:80)?'
        replacement: '${1}'

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Returns 'instance="XX:80"'

      - targets:
        - XX:80
    relabel_configs:
      - source_labels: [ __address__ ]
        target_label: instance
        regex: '(.*)(:80)?'
        replacement: '${1}'