def tags
      tags = []
      http_get('/metrics/').map do |g|
        next if g['tags'].nil?

        g['tags'].map do |k, v|
          tags << { k => v }
        end
      end
      tags.uniq!
    end
def tags
      tags = []
      http_get('/metrics/').map do |g|
        next if g['tags'].nil?

        g['tags'].map do |k, v|
          tags << { k => v }
        end
      end
      tags.uniq!
    end
Fetch all tags for metrics definitions
 @return [Hash{String=>String}]