Fix ethtool returning 0 for sanitized metrics (#3335)

The ethtool_linux looks for ethtool stats with their sanitized name
which might be different from the name provisioned by ethtool.

This caused node-exporter to return a 0-value for sanitized metrics.

This patch works-around the missing key by copying ethtool stats
to another map under their sanitized name.

Signed-off-by: Guillaume Espanel <[email protected]>
Co-authored-by: Guillaume Espanel <[email protected]>

Author: quatre

collector/ethtool_linux.go

@@ -453,6 +453,7 @@ func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {
 
 		// Sanitizing the metric names can lead to duplicate metric names. Therefore check for clashes beforehand.
 		metricFQNames := make(map[string]string)
+		renamedStats := make(map[string]uint64, len(stats))
 		for metric := range stats {
 			metricName := SanitizeMetricName(metric)
 			if !c.metricsPattern.MatchString(metricName) {
@@ -467,6 +468,8 @@ func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {
 				metricFQNames[metricFQName] = ""
 			} else {
 				metricFQNames[metricFQName] = metricName
+				// Later we'll go look for the stat with the "sanitized" metric name, so we can copy it there already
+				renamedStats[metricName] = stats[metric]
 			}
 		}
 
@@ -484,7 +487,7 @@ func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {
 				continue
 			}
 
-			val := stats[metric]
+			val := renamedStats[metric]
 
 			// Check to see if this metric exists; if not then create it and store it in c.entries.
 			entry := c.entryWithCreate(metric, metricFQName)

collector/ethtool_linux_test.go

@@ -269,6 +269,7 @@ func NewEthtoolTestCollector(logger *slog.Logger) (Collector, error) {
 
 func TestBuildEthtoolFQName(t *testing.T) {
 	testcases := map[string]string{
+		"port.rx_errors":               "node_ethtool_port_received_errors",
 		"rx_errors":                    "node_ethtool_received_errors",
 		"Queue[0] AllocFails":          "node_ethtool_queue_0_allocfails",
 		"Tx LPI entry count":           "node_ethtool_transmitted_lpi_entry_count",
@@ -292,6 +293,9 @@ node_ethtool_align_errors{device="eth0"} 0
 # HELP node_ethtool_info A metric with a constant '1' value labeled by bus_info, device, driver, expansion_rom_version, firmware_version, version.
 # TYPE node_ethtool_info gauge
 node_ethtool_info{bus_info="0000:00:1f.6",device="eth0",driver="e1000e",expansion_rom_version="",firmware_version="0.5-4",version="5.11.0-22-generic"} 1
+# HELP node_ethtool_port_received_dropped Network interface port_rx_dropped
+# TYPE node_ethtool_port_received_dropped untyped
+node_ethtool_port_received_dropped{device="eth0"} 12028
 # HELP node_ethtool_received_broadcast Network interface rx_broadcast
 # TYPE node_ethtool_received_broadcast untyped
 node_ethtool_received_broadcast{device="eth0"} 5792

collector/fixtures/ethtool/eth0/statistics

@@ -4,6 +4,7 @@ NIC statistics:
      rx_packets: 1260062
      tx_errors: 0
      rx_errors: 0
+     port.rx_dropped: 12028
      rx_missed: 401
      align_errors: 0
      tx_single_collisions: 0