Argo workflow - Prometheus metrics

https://argoproj.github.io/argo-workflows/metrics/#metric-spec

prometheus:
  # Metric name (will be prepended with "argo_workflows_").
  # Metric names can only contain alphanumeric characters, _, and :.
  - name: metric_failed_with_output_result
    # Metric definitions must include a name and a help doc string.
    # (this is a Prometheus requirement)Metrics with the
    # same name must always use the same exact help string,
    # having different metrics with the same name,
    # but with a different help string will cause an error.
    help: "test run"
    # Labels are optional. Avoid cardinality explosion.
    labels:
      - key: workflow_name
        value: "{{ workflow.name }}"
      - key: workflow_namespace
        value: "{{ workflow.namespace }}"
      - key: status
        # different workflows may fail with the same error, 
        # so add unique workflow as prefix
        value: "{{ workflow.name }}_{{ outputs.result }}"
    # Emit the metric conditionally. Works the same as normal "when"
    when: "{{ status }} == Failed"
    # The metric type. Available are "gauge", "histogram", and "counter".
    gauge:
      # This increments the counter by 1
      value: "{{duration}}"