prometheus_datacenter_coordinates.erb

# HELP consul_wan_servers_rtt_seconds Min Round trip with other servers of DC
# TYPE consul_wan_servers_rtt_seconds gauge
<%
# This computes the RTT over WAN for all DCs
results = {'min' => {}, 'max' => {}, 'p50' => {}, 'p90' => {}}
my_dcname = (agent_self['Config'] || {})['Datacenter']
my_dc = coordinate.datacenters.select { |d| d['Datacenter'] == my_dcname }.first

def percentile(values_sorted, percentile)
  k = (percentile*(values_sorted.length-1)+1).floor - 1
  f = (percentile*(values_sorted.length-1)+1).modulo(1)
  return values_sorted[k] + (f * (values_sorted[k+1] - values_sorted[k]))
end

if my_dc
  from = my_dc['Datacenter']
  coordinate.datacenters.each do |dc_coords|  
    min = Float::MAX
    max = 0
    rtts = []
    dc_coords['Coordinates'].each do |s2|
      my_dc['Coordinates'].each do |s1|
        rtt = coordinate.rtt(s1['Coord'], s2['Coord'])
        min = rtt if rtt < min
        max = rtt if rtt > max
        idx = rtts.bsearch_index { |x| x > rtt }
        if idx.nil?
          rtts << rtt
        else
          rtts = rtts.insert(idx, rtt)
        end
%>
consul_wan_servers_rtt_seconds{from="<%= from %>",to="<%= dc_coords['Datacenter'] %>",from_node="<%= s1['Node'] %>",to_node="<%= s2['Node'] %>"} <%= rtt.round(3) %><%
      end
    end
    results['min'][dc_coords['Datacenter']] = min
    results['max'][dc_coords['Datacenter']] = max
    results['p50'][dc_coords['Datacenter']] = percentile(rtts, 0.5)
    results['p90'][dc_coords['Datacenter']] = percentile(rtts, 0.9)
  end

  # Now, we iterate over aggregated results, type is min, max...
  results.each do |type, res_type|
  %>

# HELP consul_wan_dc_<%= type %>_seconds <%= type %> round trip with other DCs
# TYPE consul_wan_dc_<%= type %>_seconds gauge
<%
    # Iterate over destinations
    res_type.each do |dst, val|
%>consul_wan_dc_<%= type %>_seconds{from="<%= my_dcname %>",to="<%= dst %>"} <%= val.round(3) %>
<%
    end
  end
end
%>