fix: prometheus input plugin run outside k8s cluster error

docs/LICENSE_OF_DEPENDENCIES.md

@@ -101,7 +101,6 @@ following works:
 - github.com/emicklei/go-restful [MIT License](https://github.com/emicklei/go-restful/blob/v3/LICENSE)
 - github.com/fatih/color [MIT License](https://github.com/fatih/color/blob/master/LICENSE.md)
 - github.com/form3tech-oss/jwt-go [MIT License](https://github.com/form3tech-oss/jwt-go/blob/master/LICENSE)
-- github.com/ghodss/yaml [MIT License](https://github.com/ghodss/yaml/blob/master/LICENSE)
 - github.com/go-asn1-ber/asn1-ber [MIT License](https://github.com/go-asn1-ber/asn1-ber/blob/v1.3/LICENSE)
 - github.com/go-ldap/ldap [MIT License](https://github.com/go-ldap/ldap/blob/v3.4.1/LICENSE)
 - github.com/go-logfmt/logfmt [MIT License](https://github.com/go-logfmt/logfmt/blob/master/LICENSE)
@@ -155,6 +154,7 @@ following works:
 - github.com/hashicorp/go-uuid [Mozilla Public License 2.0](https://github.com/hashicorp/go-uuid/blob/master/LICENSE)
 - github.com/hashicorp/golang-lru [Mozilla Public License 2.0](https://github.com/hashicorp/golang-lru/blob/master/LICENSE)
 - github.com/hashicorp/serf [Mozilla Public License 2.0](https://github.com/hashicorp/serf/blob/master/LICENSE)
+- github.com/imdario/mergo [BSD 3-Clause "New" or "Revised" License](https://github.com/imdario/mergo/blob/master/LICENSE)
 - github.com/influxdata/go-syslog [MIT License](https://github.com/influxdata/go-syslog/blob/develop/LICENSE)
 - github.com/influxdata/influxdb-observability/common [MIT License](https://github.com/influxdata/influxdb-observability/blob/main/LICENSE)
 - github.com/influxdata/influxdb-observability/influx2otel [MIT License](https://github.com/influxdata/influxdb-observability/blob/main/LICENSE)
@@ -261,6 +261,7 @@ following works:
 - github.com/sirupsen/logrus [MIT License](https://github.com/sirupsen/logrus/blob/master/LICENSE)
 - github.com/sleepinggenius2/gosmi [MIT License](https://github.com/sleepinggenius2/gosmi/blob/master/LICENSE)
 - github.com/snowflakedb/gosnowflake [Apache License 2.0](https://github.com/snowflakedb/gosnowflake/blob/master/LICENSE)
+- github.com/spf13/pflag [BSD 3-Clause "New" or "Revised" License](https://github.com/spf13/pflag/blob/master/LICENSE)
 - github.com/stretchr/objx [MIT License](https://github.com/stretchr/objx/blob/master/LICENSE)
 - github.com/stretchr/testify [MIT License](https://github.com/stretchr/testify/blob/master/LICENSE)
 - github.com/testcontainers/testcontainers-go [MIT License](https://github.com/testcontainers/testcontainers-go/blob/main/LICENSE)

go.mod

@@ -61,7 +61,6 @@ require (
 	github.com/eclipse/paho.golang v0.10.0
 	github.com/eclipse/paho.mqtt.golang v1.4.1
 	github.com/fatih/color v1.13.0
-	github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32
 	github.com/go-ldap/ldap/v3 v3.4.4
 	github.com/go-logfmt/logfmt v0.5.1
 	github.com/go-ping/ping v0.0.0-20210201095549-52eed920f98c
@@ -182,6 +181,8 @@ require (
 )
 
 require (
+	github.com/imdario/mergo v0.3.12 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 // indirect
 	gopkg.in/macaroon-bakery.v3 v3.0.0 // indirect
 )

go.sum

@@ -825,8 +825,6 @@ github.com/gdamore/tcell v1.3.0/go.mod h1:Hjvr+Ofd+gLglo7RYKxxnzCBmev3BzsS67MebK
 github.com/getkin/kin-openapi v0.76.0/go.mod h1:660oXbgy5JFMKreazJaQTw7o+X00qeSyhcnluiMv+Xg=
 github.com/ghodss/yaml v0.0.0-20150909031657-73d445a93680/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
-github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32 h1:Mn26/9ZMNWSw9C9ERFA1PUxfmGpolnw2v0bKOREu5ew=
-github.com/ghodss/yaml v1.0.1-0.20190212211648-25d852aebe32/go.mod h1:GIjDIg/heH5DOkXY3YJ/wNhfHsQHoXGjl8G8amsYQ1I=
 github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
 github.com/gin-gonic/gin v1.5.0/go.mod h1:Nd6IXA8m5kNZdNEHMBd93KT+mdY3+bewLgRvmCsR2Do=
 github.com/globalsign/mgo v0.0.0-20180905125535-1ca0a4f7cbcb/go.mod h1:xkRDCp4j0OGD1HRkm4kmhM+pmpv3AKq5SU7GMg4oO/Q=
@@ -1348,6 +1346,7 @@ github.com/imdario/mergo v0.3.5/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJ
 github.com/imdario/mergo v0.3.8/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
 github.com/imdario/mergo v0.3.10/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/imdario/mergo v0.3.11/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
+github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
 github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/influxdata/flux v0.65.1/go.mod h1:J754/zds0vvpfwuq7Gc2wRdVwEodfpCFM7mYlOw2LqY=

plugins/inputs/prometheus/kubernetes.go

@@ -8,12 +8,10 @@ import (
 	"net"
 	"net/http"
 	"net/url"
-	"os"
 	"os/user"
 	"path/filepath"
 	"time"
 
-	"github.com/ghodss/yaml"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
@@ -23,6 +21,7 @@ import (
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/cache"
+	"k8s.io/client-go/tools/clientcmd"
 )
 
 type podMetadata struct {
@@ -39,41 +38,38 @@ type podResponse struct {
 
 const cAdvisorPodListDefaultInterval = 60
 
-// loadClient parses a kubeconfig from a file and returns a Kubernetes
-// client. It does not support extensions or client auth providers.
-func loadClient(kubeconfigPath string) (*kubernetes.Clientset, error) {
-	data, err := os.ReadFile(kubeconfigPath)
-	if err != nil {
-		return nil, fmt.Errorf("failed reading '%s': %v", kubeconfigPath, err)
+// loadConfig parses a kubeconfig from a file and returns a Kubernetes rest.Config
+func loadConfig(kubeconfigPath string) (*rest.Config, error) {
+	if kubeconfigPath == "" {
+		return rest.InClusterConfig()
 	}
 
-	// Unmarshal YAML into a Kubernetes config object.
-	var config rest.Config
-	if err := yaml.Unmarshal(data, &config); err != nil {
-		return nil, err
-	}
-	return kubernetes.NewForConfig(&config)
+	return clientcmd.BuildConfigFromFlags("", kubeconfigPath)
 }
 
 func (p *Prometheus) startK8s(ctx context.Context) error {
-	config, err := rest.InClusterConfig()
+	config, err := loadConfig(p.KubeConfig)
 	if err != nil {
-		return fmt.Errorf("failed to get InClusterConfig - %v", err)
+		return fmt.Errorf("failed to get rest.Config from %v - %v", p.KubeConfig, err)
 	}
+
 	client, err := kubernetes.NewForConfig(config)
 	if err != nil {
 		u, err := user.Current()
 		if err != nil {
 			return fmt.Errorf("failed to get current user - %v", err)
 		}
 
-		configLocation := filepath.Join(u.HomeDir, ".kube/config")
-		if p.KubeConfig != "" {
-			configLocation = p.KubeConfig
+		kubeconfig := filepath.Join(u.HomeDir, ".kube/config")
+
+		config, err = loadConfig(kubeconfig)
+		if err != nil {
+			return fmt.Errorf("failed to get rest.Config from %v - %v", kubeconfig, err)
 		}
-		client, err = loadClient(configLocation)
+
+		client, err = kubernetes.NewForConfig(config)
 		if err != nil {
-			return err
+			return fmt.Errorf("failed to get kubernetes client - %v", err)
 		}
 	}