feat(directives): add compose-output directive

Signed-off-by: Hidde Beydals <[email protected]>

internal/directives/output_composer.go

@@ -0,0 +1,70 @@
+package directives
+
+import (
+	"context"
+	"fmt"
+	"maps"
+
+	"github.com/xeipuuv/gojsonschema"
+
+	kargoapi "github.com/akuity/kargo/api/v1alpha1"
+)
+
+func init() {
+	builtins.RegisterPromotionStepRunner(newOutputComposer(), nil)
+}
+
+// outputComposer is an implementation of the PromotionStepRunner interface
+// that allows composing outputs from previous steps into new outputs.
+//
+// It works based on the PromotionStepContext.Config field allowing to an
+// arbitrary number of key-value pairs to be exported as outputs.
+// Because the values are allowed to be expressions and can contain
+// references to outputs from previous steps, this allows for remapping
+// the outputs of previous steps to new keys, or even combining them
+// into new structures.
+type outputComposer struct {
+	schemaLoader gojsonschema.JSONLoader
+}
+
+// newOutputComposer returns an implementation of the PromotionStepRunner
+// interface that composes output from previous steps into new output.
+func newOutputComposer() PromotionStepRunner {
+	r := &outputComposer{}
+	r.schemaLoader = getConfigSchemaLoader(r.Name())
+	return r
+}
+
+// Name implements the PromotionStepRunner interface.
+func (c *outputComposer) Name() string {
+	return "compose-output"
+}
+
+// RunPromotionStep implements the PromotionStepRunner interface.
+func (c *outputComposer) RunPromotionStep(
+	_ context.Context,
+	stepCtx *PromotionStepContext,
+) (PromotionStepResult, error) {
+	// Validate the configuration against the JSON Schema.
+	if err := validate(c.schemaLoader, gojsonschema.NewGoLoader(stepCtx.Config), c.Name()); err != nil {
+		return PromotionStepResult{Status: kargoapi.PromotionPhaseErrored}, err
+	}
+
+	// Convert the configuration into a typed object.
+	cfg, err := ConfigToStruct[ComposeOutput](stepCtx.Config)
+	if err != nil {
+		return PromotionStepResult{Status: kargoapi.PromotionPhaseErrored},
+			fmt.Errorf("could not convert config into %s config: %w", c.Name(), err)
+	}
+
+	return c.runPromotionStep(cfg)
+}
+
+func (c *outputComposer) runPromotionStep(
+	cfg ComposeOutput,
+) (PromotionStepResult, error) {
+	return PromotionStepResult{
+		Status: kargoapi.PromotionPhaseSucceeded,
+		Output: maps.Clone(cfg),
+	}, nil
+}

internal/directives/schemas/compose-output.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "title": "ComposeOutput",
+  "type": "object",
+  "minProperties": 1
+}

ui/src/gen/directives/compose-output.json

@@ -0,0 +1,6 @@
+{
+ "$schema": "https://json-schema.org/draft/2020-12/schema",
+ "title": "ComposeOutput",
+ "type": "object",
+ "minProperties": 1
+}