fix: Retry on NGINX LB errors (#273)

* Retry on NGINX LB errors

* use HTML

* go fumpt

Author: LBGarber

client.go

@@ -239,6 +239,7 @@ func (c *Client) SetRetries() *Client {
 		addRetryConditional(tooManyRequestsRetryCondition).
 		addRetryConditional(serviceUnavailableRetryCondition).
 		addRetryConditional(requestTimeoutRetryCondition).
+		addRetryConditional(requestNGINXRetryCondition).
 		SetRetryMaxWaitTime(APIRetryMaxWaitTime)
 	configureRetries(c)
 	return c

retries.go

@@ -74,6 +74,12 @@ func requestTimeoutRetryCondition(r *resty.Response, _ error) bool {
 	return r.StatusCode() == http.StatusRequestTimeout
 }
 
+func requestNGINXRetryCondition(r *resty.Response, _ error) bool {
+	return r.StatusCode() == http.StatusBadRequest &&
+		r.Header().Get("Server") == "nginx" &&
+		r.Header().Get("Content-Type") == "text/html"
+}
+
 func respectRetryAfter(client *resty.Client, resp *resty.Response) (time.Duration, error) {
 	retryAfterStr := resp.Header().Get(retryAfterHeaderName)
 	if retryAfterStr == "" {

test/integration/client_test.go

@@ -1,6 +1,10 @@
 package integration
 
 import (
+	"context"
+	"github.com/jarcoal/httpmock"
+	"github.com/linode/linodego"
+	"net/http"
 	"testing"
 )
 
@@ -26,3 +30,39 @@ func TestClient_Aliases(t *testing.T) {
 		t.Error("Expected alias for Volumes to return a *Resource")
 	}
 }
+
+func TestClient_NGINXRetry(t *testing.T) {
+	client := createMockClient(t)
+
+	// Recreate the NGINX LB error
+	nginxErrorFunc := func(request *http.Request) (*http.Response, error) {
+		resp := httpmock.NewStringResponse(400, "")
+
+		resp.Header.Add("Server", "nginx")
+		resp.Header.Set("Content-Type", "text/html")
+
+		return resp, nil
+	}
+
+	step := 0
+
+	httpmock.RegisterRegexpResponder("PUT",
+		mockRequestURL(t, "/profile"), func(request *http.Request) (*http.Response, error) {
+			if step == 0 {
+				step++
+				return nginxErrorFunc(request)
+			}
+
+			step++
+			return httpmock.NewJsonResponse(200, nil)
+		})
+
+	if _, err := client.UpdateProfile(context.Background(),
+		linodego.ProfileUpdateOptions{}); err != nil {
+		t.Fatal(err)
+	}
+
+	if step != 2 {
+		t.Fatalf("retry checks did not finish")
+	}
+}