[WIP] Add tags as labels to prometheus metrics #898

Description

Fixes #680 - Once working, this should add any tags added in the UI as labels for Prometheus

Type of change

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New feature (non-breaking change which adds functionality)

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@chakflying / @louislam - I'm not sure how to do this in NodeJS, hopefully this is a reasonable start to show the kind of thing I'm trying to achieve?

Instead of

monitor_status{monitor_name="news.bbc.co.uk",monitor_type="http",monitor_url="https://news.bbc.co.uk",monitor_hostname="null",monitor_port="null"} 1

then I should see

monitor_status{monitor_name="news.bbc.co.uk",monitor_type="http",monitor_url="https://news.bbc.co.uk",monitor_hostname="null",monitor_port="null", my_tag_1="my_value_1", my_tag_2="my_value_2"} 1

Does that make sense?

If that's the data structure you want, you would probably do this:

for (const tag of monitor.tags) {
  this.monitorLabelValues[tag.name] = tag.value
}

Looks like the tags aren't part of the monitor object?

console.log(monitor); returns the following

Monitor {
  beanMeta: BeanMeta {
    noCache: false,
    fetchAs: '',
    alias: '',
    via: '',
    withCondition: '',
    withConditionData: []
  },
  _id: 5,
  _name: 'news.bbc.co.uk',
  _active: 1,
  _userId: 1,
  _interval: 60,
  _url: 'https://news.bbc.co.uk',
  _type: 'http',
  _weight: 2000,
  _hostname: null,
  _port: null,
  _createdDate: '2021-11-09 15:40:17',
  _keyword: null,
  _maxretries: 0,
  _ignoreTls: 0,
  _upsideDown: 0,
  _maxredirects: 10,
  _acceptedStatuscodesJson: '["200-299"]',
  _dnsResolveType: 'A',
  _dnsResolveServer: '1.1.1.1',
  _dnsLastResult: null,
  _retryInterval: 60,
  _pushToken: null,
  _method: 'GET',
  _body: null,
  _headers: null
}

however I'd expect it to include two tags based on the data in the UI: