add custom header to every request with the calling function name

pagerduty/config.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"runtime"
+	"strings"
 	"sync"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/logging"
@@ -53,6 +55,8 @@ func (c *Config) Client() (*pagerduty.Client, error) {
 
 	// Return the previously-configured client if available.
 	if c.client != nil {
+		// Set caller name to x-terraform-function custom header if client was cached
+		c.client.SetXTerraformFunctionHeader(extractCallerName(2))
 		return c.client, nil
 	}
 
@@ -71,11 +75,12 @@ func (c *Config) Client() (*pagerduty.Client, error) {
 	}
 
 	config := &pagerduty.Config{
-		BaseURL:    apiUrl,
-		Debug:      logging.IsDebugOrHigher(),
-		HTTPClient: httpClient,
-		Token:      c.Token,
-		UserAgent:  c.UserAgent,
+		BaseURL:                  apiUrl,
+		Debug:                    logging.IsDebugOrHigher(),
+		HTTPClient:               httpClient,
+		Token:                    c.Token,
+		UserAgent:                c.UserAgent,
+		XTerraformFunctionHeader: extractCallerName(2),
 	}
 
 	client, err := pagerduty.NewClient(config)
@@ -135,3 +140,19 @@ func (c *Config) SlackClient() (*pagerduty.Client, error) {
 
 	return c.slackClient, nil
 }
+
+func extractCallerName(skip int) string {
+	var callerName string
+
+	pc, _, _, ok := runtime.Caller(skip)
+	details := runtime.FuncForPC(pc)
+	if ok && details != nil {
+		name := details.Name()
+		idx := strings.LastIndex(name, ".")
+		if idx > 0 {
+			callerName = name[idx+1:]
+		}
+	}
+
+	return callerName
+}

pagerduty/config_test.go

@@ -65,3 +65,37 @@ func TestConfigCustomAppUrl(t *testing.T) {
 		t.Fatalf("error: expected the client to not fail: %v", err)
 	}
 }
+
+func TestConfigXTerraformFunctionHeader(t *testing.T) {
+	config := Config{
+		Token:               "foo",
+		AppUrl:              "https://app.domain.tld",
+		SkipCredsValidation: true,
+	}
+
+	client, err := config.Client()
+	if err != nil {
+		t.Fatalf("error: expected the client to not fail: %v", err)
+	}
+	want := "TestConfigXTerraformFunctionHeader"
+	if got := client.Config.XTerraformFunctionHeader; got != want {
+		t.Fatalf("error: expected %q as value for \"x-terraform-function-header\", but got %q", want, got)
+	}
+}
+
+func TestExtractCallerName(t *testing.T) {
+	cases := []struct {
+		skip int
+		want string
+	}{
+		{0, "extractCallerName"},
+		{1, "TestExtractCallerName"},
+		{2, "tRunner"},
+	}
+
+	for _, c := range cases {
+		if got := extractCallerName(c.skip); got != c.want {
+			t.Fatalf("error: expected %q, but got %q", c.want, got)
+		}
+	}
+}