fix(metric): Update dynamic interface label to be constant (#1078)

# Description

Updated dynamic interface label for `interface_stats` metric to be set
to `all_interfaces`. Also did some optimisation on the `EthtoolStats`
struct. All stat names will be accumulated across all interface names

## Related Issue

#1067

## Checklist

- [x] I have read the [contributing
documentation](https://retina.sh/docs/contributing).
- [x] I signed and signed-off the commits (`git commit -S -s ...`). See
[this
documentation](https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification)
on signing commits.
- [x] I have correctly attributed the author(s) of the code.
- [x] I have tested the changes locally.
- [x] I have followed the project's style guidelines.
- [x] I have updated the documentation, if necessary.
- [ ] I have added tests, if applicable.

## Screenshots (if applicable) or Testing Completed

Please add any relevant screenshots or GIFs to showcase the changes
made.

## Additional Notes

Add any additional notes or context about the pull request here.

---

Please refer to the [CONTRIBUTING.md](../CONTRIBUTING.md) file for more
information on how to contribute to this project.

pkg/plugin/linuxutil/ethtool_stats_linux.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/microsoft/retina/pkg/log"
 	"github.com/microsoft/retina/pkg/metrics"
+	"github.com/microsoft/retina/pkg/utils"
 	"github.com/safchain/ethtool"
 	"go.uber.org/zap"
 )
@@ -60,7 +61,7 @@ func (er *EthtoolReader) readInterfaceStats() error {
 	defer er.ethHandle.Close()
 
 	er.data = &EthtoolStats{
-		stats: make(map[string]map[string]uint64),
+		stats: make(map[string]uint64),
 	}
 
 	for _, i := range ifaces {
@@ -83,12 +84,12 @@ func (er *EthtoolReader) readInterfaceStats() error {
 			continue
 		}
 
-		er.data.stats[i.Name] = make(map[string]uint64)
 		tempMap := er.processStats(ifaceStats)
-		er.data.stats[i.Name] = tempMap
+		for key, value := range tempMap {
+			er.data.stats[key] += value
+		}
 
 		er.l.Debug("Processed ethtool Stats ", zap.String("ifacename", i.Name))
-
 	}
 
 	return nil
@@ -114,10 +115,8 @@ func (er *EthtoolReader) processStats(ifaceStats map[string]uint64) map[string]u
 
 func (er *EthtoolReader) updateMetrics() {
 	// update metrics section
-	// retrive interfacename and statname from ethStats
-	for ifName, stats := range er.data.stats {
-		for statName, statVal := range stats {
-			metrics.InterfaceStatsGauge.WithLabelValues(ifName, statName).Set(float64(statVal))
-		}
+	// retrive statname from ethStats
+	for statName, statVal := range er.data.stats {
+		metrics.InterfaceStatsGauge.WithLabelValues(utils.InterfaceNameConstant, statName).Set(float64(statVal))
 	}
 }

pkg/plugin/linuxutil/types_linux.go

@@ -35,7 +35,7 @@ var netstatCuratedKeys = map[string]struct{}{
 	"DataCsumErr":        {},
 	"AddAddrDrop":        {},
 	"RmAddrDrop":         {},
-	"TCPTimeouts": 	      {},
+	"TCPTimeouts":        {},
 	"TCPLossProbes":      {},
 	"TCPLostRetransmit":  {},
 }
@@ -95,8 +95,8 @@ type NetstatOpts struct {
 }
 
 type EthtoolStats struct {
-	// Stats by interface name and stat name
-	stats map[string]map[string]uint64
+	// Stats by name
+	stats map[string]uint64
 }
 
 type EthtoolOpts struct {

pkg/utils/attr_utils.go

@@ -34,21 +34,22 @@ var (
 	remoteNodeKey      = attribute.Key("remote_node")
 
 	// todo move to attributes pkg?
-	Type           = "type"
-	Reason         = "reason"
-	Direction      = "direction"
-	SourceNodeName = "source_node_name"
-	TargetNodeName = "target_node_name"
-	State          = "state"
-	Address        = "address"
-	Port           = "port"
-	StatName       = "statistic_name"
-	InterfaceName  = "interface_name"
-	Flag           = "flag"
-	Endpoint       = "endpoint"
-	AclRule        = "aclrule"
-	Active         = "ACTIVE"
-	Device         = "device"
+	Type                  = "type"
+	Reason                = "reason"
+	Direction             = "direction"
+	SourceNodeName        = "source_node_name"
+	TargetNodeName        = "target_node_name"
+	State                 = "state"
+	Address               = "address"
+	Port                  = "port"
+	StatName              = "statistic_name"
+	InterfaceName         = "interface_name"
+	InterfaceNameConstant = "all_interfaces"
+	Flag                  = "flag"
+	Endpoint              = "endpoint"
+	AclRule               = "aclrule"
+	Active                = "ACTIVE"
+	Device                = "device"
 
 	// TCP Connection Statistic Names
 	ResetCount           = "ResetCount"