Use seconds in haproxy_check_duration_seconds as unit (#183)

According to Prometheus best practices, metrics should be using base
units. Times should be exported in seconds, the check duration metric is
the only outlier here.

With this change, all tested metrics adhere to the guidelines:

    for file in test/*.metrics; do
      promtool check metrics < $file
    done

Signed-off-by: Tobias Schmidt <tobidt@gmail.com>

haproxy_exporter.go

@@ -53,15 +53,17 @@ const (
 	// pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq,dresp,ereq,econ,eresp,wretr,wredis,status,weight,act,bck,chkfail,chkdown,lastchg,downtime,qlimit,pid,iid,sid,throttle,lbtot,tracked,type,rate,rate_lim,rate_max,check_status,check_code,check_duration,hrsp_1xx,hrsp_2xx,hrsp_3xx,hrsp_4xx,hrsp_5xx,hrsp_other,hanafail,req_rate,req_rate_max,req_tot,cli_abrt,srv_abrt,comp_in,comp_out,comp_byp,comp_rsp,lastsess,last_chk,last_agt,qtime,ctime,rtime,ttime,
 	// HAProxy 1.7
 	// pxname,svname,qcur,qmax,scur,smax,slim,stot,bin,bout,dreq,dresp,ereq,econ,eresp,wretr,wredis,status,weight,act,bck,chkfail,chkdown,lastchg,downtime,qlimit,pid,iid,sid,throttle,lbtot,tracked,type,rate,rate_lim,rate_max,check_status,check_code,check_duration,hrsp_1xx,hrsp_2xx,hrsp_3xx,hrsp_4xx,hrsp_5xx,hrsp_other,hanafail,req_rate,req_rate_max,req_tot,cli_abrt,srv_abrt,comp_in,comp_out,comp_byp,comp_rsp,lastsess,last_chk,last_agt,qtime,ctime,rtime,ttime,agent_status,agent_code,agent_duration,check_desc,agent_desc,check_rise,check_fall,check_health,agent_rise,agent_fall,agent_health,addr,cookie,mode,algo,conn_rate,conn_rate_max,conn_tot,intercepted,dcon,dses
-	pxnameField          = 0
-	svnameField          = 1
-	typeField            = 32
 	minimumCsvFieldCount = 33
-	statusField          = 17
-	qtimeMsField         = 58
-	ctimeMsField         = 59
-	rtimeMsField         = 60
-	ttimeMsField         = 61
+
+	pxnameField        = 0
+	svnameField        = 1
+	statusField        = 17
+	typeField          = 32
+	checkDurationField = 38
+	qtimeMsField       = 58
+	ctimeMsField       = 59
+	rtimeMsField       = 60
+	ttimeMsField       = 61
 
 	excludedServerStates = ""
 	showStatCmd          = "show stat\n"
@@ -151,7 +153,7 @@ var (
 		30: newServerMetric("server_selected_total", "Total number of times a server was selected, either for new sessions, or when re-dispatching.", prometheus.CounterValue, nil),
 		33: newServerMetric("current_session_rate", "Current number of sessions per second over last elapsed second.", prometheus.GaugeValue, nil),
 		35: newServerMetric("max_session_rate", "Maximum observed number of sessions per second.", prometheus.GaugeValue, nil),
-		38: newServerMetric("check_duration_milliseconds", "Previously run health check duration, in milliseconds", prometheus.GaugeValue, nil),
+		38: newServerMetric("check_duration_seconds", "Previously run health check duration, in seconds", prometheus.GaugeValue, nil),
 		39: newServerMetric("http_responses_total", "Total of HTTP responses.", prometheus.CounterValue, prometheus.Labels{"code": "1xx"}),
 		40: newServerMetric("http_responses_total", "Total of HTTP responses.", prometheus.CounterValue, prometheus.Labels{"code": "2xx"}),
 		41: newServerMetric("http_responses_total", "Total of HTTP responses.", prometheus.CounterValue, prometheus.Labels{"code": "3xx"}),
@@ -500,7 +502,7 @@ func (e *Exporter) exportCsvFields(metrics map[int]metricInfo, csvRow []string,
 		case statusField:
 			valueInt = parseStatusField(valueStr)
 			value = float64(valueInt)
-		case qtimeMsField, ctimeMsField, rtimeMsField, ttimeMsField:
+		case checkDurationField, qtimeMsField, ctimeMsField, rtimeMsField, ttimeMsField:
 			value, err = strconv.ParseFloat(valueStr, 64)
 			value /= 1000
 		default:

test/server_broken_csv.metrics

@@ -14,11 +14,11 @@ haproxy_server_bytes_in_total{backend="foo",server="foo-instance-0"} 0
 haproxy_server_bytes_out_total{backend="foo",server="BACKEND"} 0
 haproxy_server_bytes_out_total{backend="foo",server="FRONTEND"} 0
 haproxy_server_bytes_out_total{backend="foo",server="foo-instance-0"} 0
-# HELP haproxy_server_check_duration_milliseconds Previously run health check duration, in milliseconds
-# TYPE haproxy_server_check_duration_milliseconds gauge
-haproxy_server_check_duration_milliseconds{backend="foo",server="BACKEND"} 0
-haproxy_server_check_duration_milliseconds{backend="foo",server="FRONTEND"} 0
-haproxy_server_check_duration_milliseconds{backend="foo",server="foo-instance-0"} 0
+# HELP haproxy_server_check_duration_seconds Previously run health check duration, in seconds
+# TYPE haproxy_server_check_duration_seconds gauge
+haproxy_server_check_duration_seconds{backend="foo",server="BACKEND"} 0
+haproxy_server_check_duration_seconds{backend="foo",server="FRONTEND"} 0
+haproxy_server_check_duration_seconds{backend="foo",server="foo-instance-0"} 0
 # HELP haproxy_server_check_failures_total Total number of failed health checks.
 # TYPE haproxy_server_check_failures_total counter
 haproxy_server_check_failures_total{backend="foo",server="BACKEND"} 0