ref: make NewClient() api wrapper accept token as input

It feels like the proper thing to do is have the NewClient() wrapper
func accept the token as a struct field param to use to configure the
api client similar to the other params, rather than have this internal
wrapper func find and retrieve the token itself from the env.

This refactors things to surface the token retreival to the main package
in the `Run()` func for use with creating the api client to provide to
the exporter/sd workers.

cmd/ns1_exporter/ns1_exporter.go

@@ -159,7 +159,14 @@ func main() {
 }
 
 func Run(logger log.Logger) {
+	token := os.Getenv("NS1_APIKEY")
+	if token == "" {
+		level.Error(logger).Log("err", "NS1_APIKEY environment variable is not set")
+		os.Exit(1)
+	}
+
 	apiClient := ns1.NewClient(ns1.APIConfig{
+		Token:       token,
 		Concurrency: *flagNS1Concurrency,
 		UserAgent:   fmt.Sprintf("ns1_exporter/%s", version.Version),
 		// EnableDDI:   *flagNS1EnableDDI,

pkg/ns1/api.go

@@ -17,7 +17,6 @@ package ns1
 import (
 	"crypto/tls"
 	"net/http"
-	"os"
 	"regexp"
 	"time"
 
@@ -30,6 +29,7 @@ import (
 )
 
 type APIConfig struct {
+	Token         string
 	Concurrency   int
 	Endpoint      string
 	TLSSkipVerify bool
@@ -66,14 +66,8 @@ type QPS struct {
 
 // NewClient creates a new NS1 API client based on the provided config
 func NewClient(config APIConfig) *api.Client {
-	token := os.Getenv("NS1_APIKEY")
-	if token == "" {
-		level.Error(logger).Log("err", "NS1_APIKEY environment variable is not set")
-		os.Exit(1)
-	}
-
 	httpClient := &http.Client{Timeout: time.Second * 15}
-	clientOpts := []func(*api.Client){api.SetAPIKey(token), api.SetFollowPagination(true), api.SetUserAgent(config.UserAgent)}
+	clientOpts := []func(*api.Client){api.SetAPIKey(config.Token), api.SetFollowPagination(true), api.SetUserAgent(config.UserAgent)}
 
 	if config.Endpoint != "" {
 		clientOpts = append(clientOpts, api.SetEndpoint(config.Endpoint))