[KATC] Add snake case row transform step (#1765)

ee/katc/case.go

@@ -0,0 +1,18 @@
+package katc
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/serenize/snaker"
+)
+
+func camelToSnake(_ context.Context, _ *slog.Logger, row map[string][]byte) (map[string][]byte, error) {
+	snakeCaseRow := make(map[string][]byte)
+	for k, v := range row {
+		snakeCaseKey := snaker.CamelToSnake(k)
+		snakeCaseRow[snakeCaseKey] = v
+	}
+
+	return snakeCaseRow, nil
+}

ee/katc/case_test.go

@@ -0,0 +1,41 @@
+package katc
+
+import (
+	"context"
+	"testing"
+
+	"github.com/kolide/launcher/pkg/log/multislogger"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_camelToSnake(t *testing.T) {
+	t.Parallel()
+
+	for _, tt := range []struct {
+		testCaseName   string
+		input          string
+		expectedOutput string
+	}{
+		{
+			testCaseName:   "basic camelcase column name",
+			input:          "emailAddress",
+			expectedOutput: "email_address",
+		},
+		{
+			testCaseName:   "already snake case",
+			input:          "email_address",
+			expectedOutput: "email_address",
+		},
+	} {
+		tt := tt
+		t.Run(tt.testCaseName, func(t *testing.T) {
+			t.Parallel()
+
+			outputRows, err := camelToSnake(context.TODO(), multislogger.NewNopLogger(), map[string][]byte{
+				tt.input: nil,
+			})
+			require.NoError(t, err)
+			require.Contains(t, outputRows, tt.expectedOutput)
+		})
+	}
+}

ee/katc/config.go

@@ -59,6 +59,7 @@ type rowTransformStep struct {
 const (
 	snappyDecodeTransformStep       = "snappy"
 	deserializeFirefoxTransformStep = "deserialize_firefox"
+	camelToSnakeTransformStep       = "camel_to_snake"
 )
 
 func (r *rowTransformStep) UnmarshalJSON(data []byte) error {
@@ -77,6 +78,10 @@ func (r *rowTransformStep) UnmarshalJSON(data []byte) error {
 		r.name = deserializeFirefoxTransformStep
 		r.transformFunc = deserializeFirefox
 		return nil
+	case camelToSnakeTransformStep:
+		r.name = camelToSnakeTransformStep
+		r.transformFunc = camelToSnake
+		return nil
 	default:
 		return fmt.Errorf("unknown data processing step %s", s)
 	}

ee/katc/config_test.go

@@ -49,7 +49,7 @@ func TestConstructKATCTables(t *testing.T) {
 					"columns": ["col1", "col2"],
 					"source": "/some/path/to/a/different/db.sqlite",
 					"query": "SELECT col1, col2 FROM some_table;",
-					"row_transform_steps": []
+					"row_transform_steps": ["camel_to_snake"]
 				}`, runtime.GOOS),
 			},
 			expectedPluginCount: 2,