Add go report and fix issues from it

README.md

@@ -2,6 +2,7 @@
 
 [![Project Status](https://opensource.box.com/badges/active.svg)](https://opensource.box.com/badges)
 [![Build Status](https://travis-ci.com/box/kube-iptables-tailer.svg?token=xQMR2mqCqLKhWA2AL639&branch=master)](https://travis-ci.com/box/kube-iptables-tailer)
+[![Go Report Card](https://goreportcard.com/badge/github.com/box/kube-iptables-tailer)](https://goreportcard.com/report/github.com/box/kube-iptables-tailer)
 
 kube-iptables-tailer is a service that gives you better visibility on networking issues in your Kubernetes cluster by detecting the traffic denied by iptables and surfacing corresponding information to the affected Pods via Kubernetes events.
 

drop/parser.go

@@ -1,7 +1,6 @@
 package drop
 
 import (
-	"errors"
 	"fmt"
 	"github.com/box/kube-iptables-tailer/util"
 	"github.com/golang/glog"
@@ -24,7 +23,7 @@ type PacketDrop struct {
 
 var fieldCount = reflect.ValueOf(PacketDrop{}).NumField()
 
-// Check if PacketDrop is expired
+// IsExpired returns true if PacketDrop is expired
 func (pd PacketDrop) IsExpired() bool {
 	logTime, err := pd.GetLogTime()
 	if err != nil {
@@ -37,12 +36,12 @@ func (pd PacketDrop) IsExpired() bool {
 	return curTime.Sub(logTime).Minutes() > expiredMinutes
 }
 
-// Get the time object of PacketDrop log time
+// GetLogTime returns the time object of PacketDrop log time
 func (pd PacketDrop) GetLogTime() (time.Time, error) {
 	return time.Parse(PacketDropLogTimeLayout, pd.LogTime)
 }
 
-// Parse the logs from given channel and insert objects of PacketDrop as parsing result to another channel
+// RunParsing parses the logs from given channel and inserts objects of PacketDrop as parsing result to another channel
 func RunParsing(logPrefix string, logChangeCh <-chan string, packetDropCh chan<- PacketDrop) {
 	for log := range logChangeCh {
 		parseErr := parse(logPrefix, log, packetDropCh)
@@ -117,7 +116,7 @@ func getPacketDropLogFields(packetDropLog string) ([]string, error) {
 	logFields := strings.Fields(packetDropLog)
 	// check if the logFields contain enough information about a packet drop
 	if len(logFields) < fieldCount {
-		return []string{}, errors.New(fmt.Sprintf("Invalid packet drop: log=%+v", packetDropLog))
+		return []string{}, fmt.Errorf("error invalid packet drop: log=%+v", packetDropLog)
 	}
 	return logFields, nil
 }
@@ -128,11 +127,11 @@ func getFieldValue(logFields []string, fieldName string) (string, error) {
 		if strings.HasPrefix(field, fieldName) {
 			fieldStrs := strings.Split(field, "=")
 			if len(fieldStrs) < 2 {
-				return "", errors.New(fmt.Sprintf("Missing value: field=%+v", fieldName))
+				return "", fmt.Errorf("error missing value: field=%+v", fieldName)
 			}
 			return fieldStrs[1], nil
 
 		}
 	}
-	return "", errors.New(fmt.Sprintf("Missing field=%+v", fieldName))
+	return "", fmt.Errorf("error missing field=%+v", fieldName)
 }

drop/watcher.go

@@ -2,7 +2,6 @@ package drop
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"github.com/golang/glog"
 	"io"
@@ -20,7 +19,7 @@ type Watcher struct {
 	curFingerprint   string
 }
 
-// Init a watcher object and return its pointer
+// InitWatcher inits a watcher object and return its pointer
 func InitWatcher(watchFileName string, watchInterval time.Duration) *Watcher {
 	watcher := Watcher{watchFileName: watchFileName, watchInterval: watchInterval}
 	return &watcher
@@ -84,10 +83,10 @@ func (watcher *Watcher) checkRotation(input io.Reader) error {
 	sizeRead, err := input.Read(bytes)
 	// check sizeRead before err according to documentation of Reader.Read()
 	if sizeRead < fingerprintSize {
-		return errors.New(fmt.Sprint("Error getting fingerprint, insufficient content."))
+		return fmt.Errorf("error getting fingerprint due to insufficient content, size read:%v", sizeRead)
 	}
 	if err != nil {
-		return errors.New(fmt.Sprintf("Error checking rotation: error=%+v", err.Error()))
+		return fmt.Errorf("error checking rotation: error=%+v", err.Error())
 	}
 	fingerprint := string(bytes[:])
 	if fingerprint != watcher.curFingerprint {

event/locator.go

@@ -3,7 +3,6 @@ package event
 import (
 	"bytes"
 	"context"
-	"errors"
 	"fmt"
 	"github.com/box/kube-iptables-tailer/util"
 	"github.com/golang/glog"
@@ -20,10 +19,12 @@ type DnsResolver interface {
 	LookupAddr(context context.Context, ip string) (names []string, err error)
 }
 
+// NodeGetter has an method to get a worker node in Kubernetes
 type NodeGetter interface {
 	Get(name string, options metav1.GetOptions) (*v1.Node, error)
 }
 
+// TrafficDirection is used while generating message for Kubernetes events
 type TrafficDirection int
 
 const (
@@ -44,6 +45,7 @@ func (td TrafficDirection) String() string {
 
 const indexerName = "podIp"
 
+// Locator has methods to work with locating Pods in Kubernetes
 type Locator interface {
 	Run(stopCh <-chan struct{})
 	LocatePod(ip string) (*v1.Pod, error)
@@ -54,9 +56,7 @@ type PodLocator struct {
 	informer cache.SharedIndexInformer
 }
 
-/*
- * Returns a locator that pulls pod data from the apiserver
- */
+// NewApiServerPodLocator returns a locator that pulls pod data from the apiserver
 func NewApiServerPodLocator(client *kubernetes.Clientset) (*PodLocator, error) {
 	listWatch := cache.NewListWatchFromClient(
 		client.CoreV1().RESTClient(), "pods", v1.NamespaceAll, fields.Everything())
@@ -97,6 +97,7 @@ func podIPIndexer() func(obj interface{}) ([]string, error) {
 	return indexFunc
 }
 
+// Run process of locating Pods
 func (locator *PodLocator) Run(stopCh <-chan struct{}) {
 	go locator.informer.Run(stopCh)
 
@@ -106,10 +107,11 @@ func (locator *PodLocator) Run(stopCh <-chan struct{}) {
 	}
 }
 
+// LocatePod locates the pod by given IP address
 func (locator *PodLocator) LocatePod(ip string) (*v1.Pod, error) {
 	items, err := locator.informer.GetIndexer().ByIndex(indexerName, ip)
 	if err != nil {
-		return nil, errors.New(fmt.Sprintf("Error looking up pod: ip=%v", ip))
+		return nil, fmt.Errorf("error looking up Pod: ip=%v", ip)
 	} else if len(items) > 0 {
 		if pod, ok := items[0].(*v1.Pod); ok {
 			return pod, nil

event/poster.go

@@ -1,7 +1,6 @@
 package event
 
 import (
-	"errors"
 	"fmt"
 	"github.com/box/kube-iptables-tailer/drop"
 	"github.com/box/kube-iptables-tailer/metrics"
@@ -29,7 +28,7 @@ type Poster struct {
 	locator            Locator
 }
 
-// Init Poster and return its pointer
+// InitPoster inits a Poster and return its pointer
 func InitPoster() (*Poster, error) {
 	kubeClient, err := initKubeClient()
 	if err != nil {
@@ -45,7 +44,7 @@ func InitPoster() (*Poster, error) {
 
 	locator, err := NewApiServerPodLocator(kubeClient)
 	if err != nil {
-		return nil, errors.New(fmt.Sprintf("Error creating locator: %+v", err))
+		return nil, fmt.Errorf("error creating locator: %+v", err)
 	}
 
 	return &Poster{

metrics/metrics.go

@@ -18,7 +18,7 @@ type Metrics struct {
 	packetDropsCount *prometheus.CounterVec
 }
 
-// Return the singleton instance of metrics
+// GetInstance returns the singleton instance of metrics
 func GetInstance() *Metrics {
 	once.Do(initMetricsSingleton) // thread-safe way to construct the singleton instance
 	return instance
@@ -43,13 +43,13 @@ func initMetricsSingleton() {
 	instance = &Metrics{packetDropsCount: packetDropCountsVec, registry: r}
 }
 
-// Return the handler of metrics
+// GetHandler returns the handler of metrics
 func (m *Metrics) GetHandler() http.Handler {
 	// need to specify registry to avoid getting extra data sent in prometheus
 	return promhttp.HandlerFor(m.registry, promhttp.HandlerOpts{})
 }
 
-// Update the metrics by given service name
+// ProcessPacketDrop updates the metrics by given service name
 func (m *Metrics) ProcessPacketDrop(src, dst string) {
 	m.packetDropsCount.With(prometheus.Labels{
 		"src": src,

util/envar.go

@@ -38,6 +38,7 @@ const (
 	DefaultWatchLogsIntervalSecond = 5
 )
 
+// GetRequiredEnvString returns string environment variable of the given key
 func GetRequiredEnvString(key string) string {
 	val := os.Getenv(key)
 	if len(val) == 0 {
@@ -46,15 +47,7 @@ func GetRequiredEnvString(key string) string {
 	return val
 }
 
-func GetRequiredEnvInt(key string) int {
-	stringVal := GetRequiredEnvString(key)
-	intVal, err := strconv.Atoi(stringVal)
-	if err != nil {
-		log.Fatalf("Error converting environment variable %s to int: %v", stringVal, err)
-	}
-	return intVal
-}
-
+// GetRequiredEnvString returns integer environment variable of the given key or default value if key does not exist
 func GetEnvIntOrDefault(key string, def int) int {
 	if env := os.Getenv(key); env != "" {
 		val, err := strconv.Atoi(env)
@@ -67,6 +60,7 @@ func GetEnvIntOrDefault(key string, def int) int {
 	return def
 }
 
+// GetEnvStringOrDefault returns string environment variable of the given key or default value if key does not exist
 func GetEnvStringOrDefault(key string, def string) string {
 	if val := os.Getenv(key); len(val) > 0 {
 		return val

util/util.go

@@ -7,17 +7,18 @@ import (
 	"time"
 )
 
+// PrettyPrint returns the string in JSON format
 func PrettyPrint(i interface{}) string {
 	s, err := json.MarshalIndent(i, "", "  ")
 	if err != nil {
 		glog.Errorf("Error marshaling JSON: obj=%+v", i)
 		return fmt.Sprintf("%+v", i)
-	} else {
-		return string(s)
 	}
+	return string(s)
+
 }
 
-// Utility functions for packet drop testing
+// GetExpiredTimeInString returns an expired time which is used in packet drop testing
 func GetExpiredTimeInString(expirationMinutes int, timeFormat string) string {
 	duration := time.Duration(expirationMinutes) * time.Minute
 	// add one more minute than given expiration to make sure the time is expired