Instrument healthChecker with Prometheus metrics

Author: rsienko

cloud/linode/client/client_with_metrics.go

@@ -68,21 +68,9 @@ func init() {
 		})
 }
 
-func initLinodeClient() (client.Client, error) {
-	// Read environment variables (from secrets)
-	apiToken := os.Getenv(accessTokenEnv)
-	if apiToken == "" {
-		return nil, fmt.Errorf("%s must be set in the environment (use a k8s secret)", accessTokenEnv)
-	}
-
-	// set timeout used by linodeclient for API calls
-	timeout := client.DefaultClientTimeout
-	if raw, ok := os.LookupEnv("LINODE_REQUEST_TIMEOUT_SECONDS"); ok {
-		if t, err := strconv.Atoi(raw); err == nil && t > 0 {
-			timeout = time.Duration(t) * time.Second
-		}
-	}
-
+// newLinodeClientWithPrometheus creates a new client kept in its own local
+// scope and returns an instrumented one that should be used and passed around
+func newLinodeClientWithPrometheus(apiToken string, timeout time.Duration) (client.Client, error) {
 	linodeClient, err := client.New(apiToken, timeout)
 	if err != nil {
 		return nil, fmt.Errorf("client was not created succesfully: %w", err)
@@ -92,33 +80,6 @@ func initLinodeClient() (client.Client, error) {
 		linodeClient.SetDebug(true)
 	}
 
-	var healthChecker *healthChecker
-
-	if Options.EnableTokenHealthChecker {
-		authenticated, err := client.CheckClientAuthenticated(context.TODO(), linodeClient)
-		if err != nil {
-			return nil, fmt.Errorf("linode client authenticated connection error: %w", err)
-		}
-
-		if !authenticated {
-			return nil, fmt.Errorf("linode api token %q is invalid", accessTokenEnv)
-		}
-
-		healthChecker, err = newHealthChecker(apiToken, timeout, tokenHealthCheckPeriod, Options.GlobalStopChannel)
-		if err != nil {
-			return nil, fmt.Errorf("unable to initialize healthchecker: %w", err)
-		}
-	}
-
-	if Options.VPCName != "" && Options.VPCNames != "" {
-		return nil, fmt.Errorf("cannot have both vpc-name and vpc-names set")
-	}
-
-	if Options.VPCName != "" {
-		klog.Warningf("vpc-name flag is deprecated. Use vpc-names instead")
-		Options.VPCNames = Options.VPCName
-	}
-
 	return client.NewClientWithPrometheus(linodeClient), nil
 }
 
@@ -128,7 +89,21 @@ func newCloud() (cloudprovider.Interface, error) {
 		return nil, fmt.Errorf("%s must be set in the environment (use a k8s secret)", regionEnv)
 	}
 
-	linodeClient, err := initLinodeClient()
+	// Read environment variables (from secrets)
+	apiToken := os.Getenv(accessTokenEnv)
+	if apiToken == "" {
+		return nil, fmt.Errorf("%s must be set in the environment (use a k8s secret)", accessTokenEnv)
+	}
+
+	// set timeout used by linodeclient for API calls
+	timeout := client.DefaultClientTimeout
+	if raw, ok := os.LookupEnv("LINODE_REQUEST_TIMEOUT_SECONDS"); ok {
+		if t, err := strconv.Atoi(raw); err == nil && t > 0 {
+			timeout = time.Duration(t) * time.Second
+		}
+	}
+
+	linodeClient, err := newLinodeClientWithPrometheus(apiToken, timeout)
 	if err != nil {
 		return nil, err
 	}
@@ -157,6 +132,33 @@ func newCloud() (cloudprovider.Interface, error) {
 		return nil, fmt.Errorf("%s", msg)
 	}
 
+	var healthChecker *healthChecker
+
+	if Options.EnableTokenHealthChecker {
+		authenticated, err := client.CheckClientAuthenticated(context.TODO(), linodeClient)
+		if err != nil {
+			return nil, fmt.Errorf("linode client authenticated connection error: %w", err)
+		}
+
+		if !authenticated {
+			return nil, fmt.Errorf("linode api token %q is invalid", accessTokenEnv)
+		}
+
+		healthChecker, err = newHealthChecker(linodeClient, timeout, tokenHealthCheckPeriod, Options.GlobalStopChannel)
+		if err != nil {
+			return nil, fmt.Errorf("unable to initialize healthchecker: %w", err)
+		}
+	}
+
+	if Options.VPCName != "" && Options.VPCNames != "" {
+		return nil, fmt.Errorf("cannot have both vpc-name and vpc-names set")
+	}
+
+	if Options.VPCName != "" {
+		klog.Warningf("vpc-name flag is deprecated. Use vpc-names instead")
+		Options.VPCNames = Options.VPCName
+	}
+
 	// create struct that satisfies cloudprovider.Interface
 	lcloud := &linodeCloud{
 		client:                   linodeClient,

cloud/linode/cloud.go

@@ -15,12 +15,7 @@ type healthChecker struct {
 	stopCh       chan<- struct{}
 }
 
-func newHealthChecker(apiToken string, timeout time.Duration, period time.Duration, stopCh chan<- struct{}) (*healthChecker, error) {
-	client, err := client.New(apiToken, timeout)
-	if err != nil {
-		return nil, err
-	}
-
+func newHealthChecker(client client.Client, timeout time.Duration, period time.Duration, stopCh chan<- struct{}) (*healthChecker, error) {
 	return &healthChecker{
 		period:       period,
 		linodeClient: client,