Added status code checking

authority/provisioner/aws.go

@@ -196,14 +196,14 @@ func (p *AWS) GetIdentityToken(subject, caURL string) (string, error) {
 	var idoc awsInstanceIdentityDocument
 	doc, err := p.readURL(p.config.identityURL)
 	if err != nil {
-		return "", errors.Wrap(err, "error retrieving identity document, are you in an AWS VM?")
+		return "", errors.Wrap(err, "error retrieving identity document, are you in an AWS VM with IMDSv2 enabled?")
 	}
 	if err := json.Unmarshal(doc, &idoc); err != nil {
 		return "", errors.Wrap(err, "error unmarshaling identity document")
 	}
 	sig, err := p.readURL(p.config.signatureURL)
 	if err != nil {
-		return "", errors.Wrap(err, "error retrieving identity document signature, are you in an AWS VM?")
+		return "", errors.Wrap(err, "error retrieving identity document signature, are you in an AWS VM with IMDSv2 enabled?")
 	}
 	signature, err := base64.StdEncoding.DecodeString(string(sig))
 	if err != nil {
@@ -358,6 +358,9 @@ func (p *AWS) readURL(url string) ([]byte, error) {
 		return nil, err
 	}
 	defer r.Body.Close()
+	if r.StatusCode >= 400 {
+		return nil, fmt.Errorf("HTTP request returned non-successful status code %d", r.StatusCode)
+	}
 	b, err := ioutil.ReadAll(r.Body)
 	if err != nil {
 		return nil, err
@@ -375,6 +378,9 @@ func (p *AWS) readURL(url string) ([]byte, error) {
 		return nil, err
 	}
 	defer r.Body.Close()
+	if r.StatusCode >= 400 {
+		return nil, fmt.Errorf("HTTP request returned non-successful status code %d", r.StatusCode)
+	}
 	b, err = ioutil.ReadAll(r.Body)
 	if err != nil {
 		return nil, err