fix(inputs.kube_inventory): send file location to enable token auto-refresh (#11577)

plugins/inputs/kube_inventory/README.md

@@ -44,10 +44,15 @@ avoid cardinality issues:
   # namespace = "default"
 
   ## Use bearer token for authorization. ('bearer_token' takes priority)
+  ##
   ## If both of these are empty, we'll use the default serviceaccount:
   ## at: /run/secrets/kubernetes.io/serviceaccount/token
-  # bearer_token = "/path/to/bearer/token"
+  ##
+  ## To auto-refresh the token, please use a file with the bearer_token option.
+  ## If given a string, Telegraf cannot refresh the token periodically.
+  # bearer_token = "/run/secrets/kubernetes.io/serviceaccount/token"
   ## OR
+  ## deprecated in 1.24.0; use bearer_token with a file
   # bearer_token_string = "abc_123"
 
   ## Set response_timeout (default 5 seconds)

plugins/inputs/kube_inventory/client.go

@@ -20,8 +20,8 @@ type client struct {
 	*kubernetes.Clientset
 }
 
-func newClient(baseURL, namespace, bearerToken string, timeout time.Duration, tlsConfig tls.ClientConfig) (*client, error) {
-	c, err := kubernetes.NewForConfig(&rest.Config{
+func newClient(baseURL, namespace, bearerTokenFile string, bearerToken string, timeout time.Duration, tlsConfig tls.ClientConfig) (*client, error) {
+	config := &rest.Config{
 		TLSClientConfig: rest.TLSClientConfig{
 			ServerName: tlsConfig.ServerName,
 			Insecure:   tlsConfig.InsecureSkipVerify,
@@ -30,9 +30,16 @@ func newClient(baseURL, namespace, bearerToken string, timeout time.Duration, tl
 			KeyFile:    tlsConfig.TLSKey,
 		},
 		Host:          baseURL,
-		BearerToken:   bearerToken,
 		ContentConfig: rest.ContentConfig{},
-	})
+	}
+
+	if bearerTokenFile != "" {
+		config.BearerTokenFile = bearerTokenFile
+	} else if bearerToken != "" {
+		config.BearerToken = bearerToken
+	}
+
+	c, err := kubernetes.NewForConfig(config)
 	if err != nil {
 		return nil, err
 	}

plugins/inputs/kube_inventory/client_test.go

@@ -25,6 +25,9 @@ func toBoolPtr(b bool) *bool {
 }
 
 func TestNewClient(t *testing.T) {
-	_, err := newClient("https://127.0.0.1:443/", "default", "abc123", time.Second, tls.ClientConfig{})
+	_, err := newClient("https://127.0.0.1:443/", "default", "", "abc123", time.Second, tls.ClientConfig{})
 	require.NoErrorf(t, err, "Failed to create new client - %v", err)
+
+	_, err = newClient("https://127.0.0.1:443/", "default", "nonexistantFile", "", time.Second, tls.ClientConfig{})
+	require.Errorf(t, err, "failed to read token file \"file\": open file: no such file or directory", err)
 }

plugins/inputs/kube_inventory/kube_inventory.go

@@ -5,9 +5,7 @@ import (
 	"context"
 	_ "embed"
 	"fmt"
-	"os"
 	"strconv"
-	"strings"
 	"sync"
 	"time"
 
@@ -32,7 +30,7 @@ const (
 type KubernetesInventory struct {
 	URL               string          `toml:"url"`
 	BearerToken       string          `toml:"bearer_token"`
-	BearerTokenString string          `toml:"bearer_token_string"`
+	BearerTokenString string          `toml:"bearer_token_string" deprecated:"1.24.0;use 'BearerToken' with a file instead"`
 	Namespace         string          `toml:"namespace"`
 	ResponseTimeout   config.Duration `toml:"response_timeout"` // Timeout specified as a string - 3s, 1m, 1h
 	ResourceExclude   []string        `toml:"resource_exclude"`
@@ -60,16 +58,12 @@ func (ki *KubernetesInventory) Init() error {
 		ki.BearerToken = defaultServiceAccountPath
 	}
 
-	if ki.BearerToken != "" {
-		token, err := os.ReadFile(ki.BearerToken)
-		if err != nil {
-			return err
-		}
-		ki.BearerTokenString = strings.TrimSpace(string(token))
+	if ki.BearerTokenString != "" {
+		ki.Log.Warn("Telegraf cannot auto-refresh a bearer token string, use BearerToken file instead")
 	}
 
 	var err error
-	ki.client, err = newClient(ki.URL, ki.Namespace, ki.BearerTokenString, time.Duration(ki.ResponseTimeout), ki.ClientConfig)
+	ki.client, err = newClient(ki.URL, ki.Namespace, ki.BearerToken, ki.BearerTokenString, time.Duration(ki.ResponseTimeout), ki.ClientConfig)
 
 	if err != nil {
 		return err

plugins/inputs/kube_inventory/sample.conf

@@ -7,10 +7,15 @@
   # namespace = "default"
 
   ## Use bearer token for authorization. ('bearer_token' takes priority)
+  ##
   ## If both of these are empty, we'll use the default serviceaccount:
   ## at: /run/secrets/kubernetes.io/serviceaccount/token
-  # bearer_token = "/path/to/bearer/token"
+  ##
+  ## To auto-refresh the token, please use a file with the bearer_token option.
+  ## If given a string, Telegraf cannot refresh the token periodically.
+  # bearer_token = "/run/secrets/kubernetes.io/serviceaccount/token"
   ## OR
+  ## deprecated in 1.24.0; use bearer_token with a file
   # bearer_token_string = "abc_123"
 
   ## Set response_timeout (default 5 seconds)