Improve error message when chunk size > limit

Fixes open-policy-agent#5155

Signed-off-by: Anders Eknert <[email protected]>

plugins/logs/encoder.go

@@ -65,7 +65,8 @@ func (enc *chunkEncoder) Write(event EventV1) (result [][]byte, err error) {
 	if len(bs) == 0 {
 		return nil, nil
 	} else if int64(len(bs)+2) > enc.limit {
-		return nil, fmt.Errorf("upload chunk size too small")
+		return nil, fmt.Errorf("upload chunk size (%d) exceeds upload_size_limit_bytes (%d)",
+			int64(len(bs)+2), enc.limit)
 	}
 
 	if int64(len(bs)+enc.bytesWritten+1) > enc.softLimit {

plugins/logs/encoder_test.go

@@ -53,6 +53,36 @@ func TestChunkEncoder(t *testing.T) {
 	}
 }
 
+func TestChunkEncoderSizeLimit(t *testing.T) {
+	enc := newChunkEncoder(1).WithMetrics(metrics.New())
+	var result interface{} = false
+	var expInput interface{} = map[string]interface{}{"method": "GET"}
+	ts, err := time.Parse(time.RFC3339Nano, "2018-01-01T12:00:00.123456Z")
+	if err != nil {
+		t.Fatal(err)
+	}
+	event := EventV1{
+		Labels: map[string]string{
+			"id":  "test-instance-id",
+			"app": "example-app",
+		},
+		DecisionID:  "123",
+		Path:        "foo/bar",
+		Input:       &expInput,
+		Result:      &result,
+		RequestedBy: "test",
+		Timestamp:   ts,
+	}
+	_, err = enc.Write(event)
+	if err == nil {
+		t.Error("Expected error as upload chunk size exceeds configured limit")
+	}
+	expected := "upload chunk size (200) exceeds upload_size_limit_bytes (1)"
+	if err.Error() != expected {
+		t.Errorf("expected: '%s', got: '%s'", expected, err.Error())
+	}
+}
+
 func TestChunkEncoderAdaptive(t *testing.T) {
 
 	enc := newChunkEncoder(1000).WithMetrics(metrics.New())