feat(cli) Update error handling for checkHosts, Target EC2 client logic (#91)

* feat(cli) Update error handling for checkHosts, Target EC2 client logic

* feat(cli) Add UnauthorizedOperation handling to errors.go

internal/errors/error.go

@@ -29,6 +29,11 @@ const (
 	// the owner. This error cannot be resolved by retrying the request.
 	awsErrorAccessDenied = "AccessDenied"
 
+	// awsErrorUnauthorizedOperation is returned by EC2 when the caller is not
+	// authorized to perform the operation. This includes DryRun permission
+	// checks that fail (the counterpart to DryRunOperation success).
+	awsErrorUnauthorizedOperation = "UnauthorizedOperation"
+
 	// awsErrorInvalidAccessKeyId is returned when the credential does
 	// not exist. This error will persist until the credentials attached
 	// to the storage bucket is updated. This error can occur when the
@@ -66,8 +71,26 @@ const (
 
 	// RequestTimeoutException is returned when an http request takes longer than allowed
 	awsErrorRequestTimeoutException = "RequestTimeoutException"
+
+	// dryRunOperationErrorCode is returned by AWS when a DryRun request would have
+	// succeeded. It is a success signal disguised as an API error (typically HTTP 412).
+	dryRunOperationErrorCode = "DryRunOperation"
 )
 
+// IsDryRunSuccess reports whether err is the AWS DryRunOperation success signal.
+// A true result means the dry-run validated credentials, permissions, and parameters;
+// it must not be treated as a failure.
+func IsDryRunSuccess(err error) bool {
+	if err == nil {
+		return false
+	}
+	var apiErr smithy.APIError
+	if !errors.As(err, &apiErr) {
+		return false
+	}
+	return apiErr.ErrorCode() == dryRunOperationErrorCode
+}
+
 // InvalidArgumentError returns an grpc invalid argument status error.
 func InvalidArgumentError(msg string, f map[string]string) error {
 	var fieldMsgs []string
@@ -172,6 +195,8 @@ func ParseAWSError(op string, err error) (st *status.Status, permission *pb.Perm
 		switch apiErr.ErrorCode() {
 		case awsErrorAccessDenied:
 			fallthrough
+		case awsErrorUnauthorizedOperation:
+			fallthrough
 		case awsErrorInvalidAccessKeyId:
 			fallthrough
 		case awsErrorExpiredToken:

internal/errors/error_test.go

@@ -300,6 +300,17 @@ func Test_ParseAWSError(t *testing.T) {
 				CheckedAt:    timestamppb.Now(),
 			},
 		},
+		{
+			name:               "aws-request-unauthorized-operation",
+			err:                TestAwsError(awsErrorUnauthorizedOperation, "You are not authorized to perform this operation."),
+			expectedStatusCode: codes.PermissionDenied,
+			expectedStatusMsg:  "aws service unknown: invalid credentials: test",
+			expectedPermission: &pb.Permission{
+				State:        pb.StateType_STATE_TYPE_ERROR,
+				ErrorDetails: "You are not authorized to perform this operation.",
+				CheckedAt:    timestamppb.Now(),
+			},
+		},
 		{
 			name:               "aws-request-invalid-access-key-id",
 			err:                TestAwsError(awsErrorInvalidAccessKeyId, "The AWS Access Key Id you provided does not exist in our records."),
@@ -390,6 +401,46 @@ func Test_ParseAWSError(t *testing.T) {
 	}
 }
 
+func Test_IsDryRunSuccess(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{
+			name: "nil",
+			want: false,
+		},
+		{
+			name: "plain error",
+			err:  fmt.Errorf("not an aws error"),
+			want: false,
+		},
+		{
+			name: "other api error",
+			err:  TestAwsError(awsErrorAccessDenied, "not authorized"),
+			want: false,
+		},
+		{
+			name: "dry run operation",
+			err:  TestAwsError(dryRunOperationErrorCode, "Request would have succeeded, but DryRun flag is set"),
+			want: true,
+		},
+		{
+			name: "wrapped dry run operation",
+			err:  fmt.Errorf("describe instances: %w", TestAwsError(dryRunOperationErrorCode, "Request would have succeeded, but DryRun flag is set")),
+			want: true,
+		},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, IsDryRunSuccess(tt.err))
+		})
+	}
+}
+
 func Test_BadRequestStatusf(t *testing.T) {
 	require, assert := require.New(t), assert.New(t)
 	err := BadRequestStatusf("test: %s", "hello world")