Step function handler (#12)

.gitignore

@@ -1,2 +1,3 @@
 coverage.out
 .idea
+.DS_Store

handlers.go

@@ -26,6 +26,8 @@ type HandlerConfig struct {
 
 type LambdaResult interface{}
 
+type StepEvent interface{}
+
 type Validatable interface {
 	Validate() error
 }

step_function_handler.go

@@ -0,0 +1,65 @@
+package g8
+
+import (
+	"context"
+	"github.com/aws/aws-lambda-go/lambda"
+	"github.com/google/uuid"
+	newrelic "github.com/newrelic/go-agent"
+	"github.com/newrelic/go-agent/_integrations/nrlambda"
+	"github.com/rs/zerolog"
+)
+
+type StepContext struct {
+	Context       context.Context
+	Event         StepEvent
+	Logger        zerolog.Logger
+	NewRelicTx    newrelic.Transaction
+	CorrelationID string
+}
+
+type StepHandlerFunc func(c *StepContext) (StepEvent, error)
+
+func StepHandler(h StepHandlerFunc, conf HandlerConfig) func(context.Context, StepEvent) (StepEvent, error) {
+	return func(ctx context.Context, e StepEvent) (StepEvent, error) {
+		correlationID := uuid.New().String()
+
+		logger := configureLogger(conf).
+			Str("event_source", "step_function_event").
+			Str("correlation_id", correlationID).
+			Logger()
+
+		c := &StepContext{
+			Context:       ctx,
+			Event:         e,
+			Logger:        logger,
+			NewRelicTx:    newrelic.FromContext(ctx),
+			CorrelationID: correlationID,
+		}
+
+		c.AddNewRelicAttribute("functionName", conf.FunctionName)
+		c.AddNewRelicAttribute("buildVersion", conf.BuildVersion)
+		c.AddNewRelicAttribute("correlationID", correlationID)
+		c.AddNewRelicAttribute("eventSource", "step_function_event")
+
+		result, err := h(c)
+
+		if err != nil {
+			logUnhandledError(c.Logger, err)
+		}
+
+		return result, err
+	}
+}
+
+func StepHandlerWithNewRelic(h StepHandlerFunc, conf HandlerConfig) lambda.Handler {
+	return nrlambda.Wrap(StepHandler(h, conf), conf.NewRelicApp)
+}
+
+func (c *StepContext) AddNewRelicAttribute(key string, val interface{}) {
+	if c.NewRelicTx == nil {
+		return
+	}
+	if err := c.NewRelicTx.AddAttribute(key, val); err != nil {
+		c.Logger.Error().Msgf("failed to add attr '%s' to new relic tx: %+v", key, err)
+	}
+}