add json-parser step

Signed-off-by: Faeka Ansari <faeka6@gmail.com>

internal/directives/json_parser.go

@@ -0,0 +1,137 @@
+package directives
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/expr-lang/expr"
+	"github.com/xeipuuv/gojsonschema"
+
+	kargoapi "github.com/akuity/kargo/api/v1alpha1"
+)
+
+func init() {
+	builtins.RegisterPromotionStepRunner(newJSONParser(), nil)
+}
+
+// jsonParser is an implementation of the PromotionStepRunner interface that
+// parses a JSON file and extracts specified outputs.
+type jsonParser struct {
+	schemaLoader gojsonschema.JSONLoader
+}
+
+// newJSONParser returns a new instance of jsonParser.
+func newJSONParser() PromotionStepRunner {
+	r := &jsonParser{}
+	r.schemaLoader = getConfigSchemaLoader(r.Name())
+	return r
+}
+
+// Name implements the PromotionStepRunner interface.
+func (jp *jsonParser) Name() string {
+	return "json-parse"
+}
+
+func (jp *jsonParser) RunPromotionStep(
+	ctx context.Context,
+	stepCtx *PromotionStepContext,
+) (PromotionStepResult, error) {
+	failure := PromotionStepResult{Status: kargoapi.PromotionPhaseErrored}
+
+	if err := jp.validate(stepCtx.Config); err != nil {
+		return failure, err
+	}
+
+	cfg, err := ConfigToStruct[JSONParseConfig](stepCtx.Config)
+	if err != nil {
+		return failure, fmt.Errorf("could not convert config into %s config: %w", jp.Name(), err)
+	}
+
+	return jp.runPromotionStep(ctx, stepCtx, cfg)
+}
+
+// validate validates jsonParser configuration against a JSON schema.
+func (jp *jsonParser) validate(cfg Config) error {
+	return validate(jp.schemaLoader, gojsonschema.NewGoLoader(cfg), jp.Name())
+}
+
+func (jp *jsonParser) runPromotionStep(
+	_ context.Context,
+	_ *PromotionStepContext,
+	cfg JSONParseConfig,
+) (PromotionStepResult, error) {
+	failure := PromotionStepResult{Status: kargoapi.PromotionPhaseErrored}
+
+	if cfg.Path == "" {
+		return failure, fmt.Errorf("JSON file path cannot be empty")
+	}
+
+	if len(cfg.Outputs) == 0 {
+		return failure, fmt.Errorf("invalid json-parse config: outputs is required")
+	}
+
+	data, err := jp.readAndParseJSON(cfg.Path)
+	if err != nil {
+		return failure, err
+	}
+
+	extractedValues, err := jp.extractValues(data, cfg.Outputs)
+	if err != nil {
+		return failure, err
+	}
+
+	return PromotionStepResult{
+		Status: kargoapi.PromotionPhaseSucceeded,
+		Output: extractedValues,
+	}, nil
+}
+
+// readAndParseJSON reads a JSON file and unmarshals it into a map.
+func (jp *jsonParser) readAndParseJSON(path string) (map[string]any, error) {
+	jsonData, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("could not read file: %w", err)
+	}
+
+	var data map[string]any
+	if err := json.Unmarshal(jsonData, &data); err != nil {
+		return nil, fmt.Errorf("could not parse JSON: %w", err)
+	}
+
+	return data, nil
+}
+
+// extractValues evaluates JSONPath expressions using expr and returns extracted values.
+func (jp *jsonParser) extractValues(data map[string]any, outputs []JSONParse) (map[string]any, error) {
+	results := make(map[string]any)
+
+	for _, output := range outputs {
+		value, err := jp.evaluateExpression(data, output.FromExpression)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract outputs from '%s': %w", output.FromExpression, err)
+		}
+		results[output.Name] = value
+	}
+
+	return results, nil
+}
+
+// evaluateExpression compiles and runs an expression against the JSON data.
+func (jp *jsonParser) evaluateExpression(
+	data map[string]any,
+	expression string,
+) (any, error) {
+	program, err := expr.Compile(expression, expr.Env(data))
+	if err != nil {
+		return nil, fmt.Errorf("error compiling expression: %w", err)
+	}
+
+	result, err := expr.Run(program, data)
+	if err != nil {
+		return nil, fmt.Errorf("error evaluating expression: %w", err)
+	}
+
+	return result, nil
+}