Ensure http client Transport is defined before trying to set Insecure…

…SkipVerify

The http client we get from the oci-go-sdk lets it default to
http.DefaultTransport, but this isn't set at the time we try and
configure the TLSClientConfig to set InsecureSkipVerify to true
(when the provider has disable-certs set).

provider/oracle/oracle_common.go

@@ -143,16 +143,20 @@ func (t ociSigningRoundTripper) intercept(request *http.Request) (err error) {
 
 // Skip verification of insecure certs
 func InsecureRoundTripper(roundTripper http.RoundTripper) http.RoundTripper {
-	transport := roundTripper.(*http.Transport)
-	if transport != nil {
+	if roundTripper == nil {
+		roundTripper = http.DefaultTransport
+	}
+
+	if transport, ok := roundTripper.(*http.Transport); ok {
 		if transport.TLSClientConfig != nil {
 			transport.TLSClientConfig.InsecureSkipVerify = true
 		} else {
 			transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
 		}
+		return transport
 	}
 
-	return transport
+	return nil
 }
 
 //-- Provider interface impl ----------------------------------------------------------------------------------

provider/oracle/oracle_common_test.go

@@ -0,0 +1,26 @@
+package oracle
+
+import (
+	"net/http"
+	"testing"
+)
+
+func TestInsecureRoundTripper(t *testing.T) {
+	testCases := []http.RoundTripper{
+		http.DefaultTransport, // Normal case
+		nil,                   // Ensure it creates a DefaultTransport in the nil case
+	}
+
+	for _, transport := range testCases {
+		roundTripper := InsecureRoundTripper(transport)
+		transport, ok := roundTripper.(*http.Transport)
+
+		if !ok {
+			t.Fatal("Transport not correctly returned")
+		}
+
+		if transport.TLSClientConfig == nil || !transport.TLSClientConfig.InsecureSkipVerify {
+			t.Fatal("InsecureSkipVerify not correctly set on transport")
+		}
+	}
+}