Eliminate redundant Describe call and add ErrFunctionNotFound

Move the "not found" error detection from the controller into
funccli.Describe as a typed ErrFunctionNotFound sentinel error.
Pass the initial Describe result through to checkMiddlewareState,
removing one Describe roundtrip per reconcile.

Author: creydr

internal/controller/function_controller.go

@@ -18,6 +18,7 @@ package controller
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -218,17 +219,16 @@ func (r *FunctionReconciler) reconcileDeployment(ctx context.Context, function *
 	logger := log.FromContext(ctx)
 	logger.Info("Reconciling Function")
 
-	deployed, err := r.isDeployed(ctx, metadata.Name, function.Namespace)
-	if err != nil {
-		function.MarkDeployNotReady("DeployFailed", "Failed to check deployment status: %s", err.Error())
-		return fmt.Errorf("failed to check if function is already deployed: %w", err)
-	}
-
-	if !deployed {
+	initialDesc, err := r.FuncCliManager.Describe(ctx, metadata.Name, function.Namespace)
+	if errors.Is(err, funccli.ErrFunctionNotFound) {
 		logger.Info("Function is not deployed")
 		function.MarkDeployNotReady("NotDeployed", "Function not deployed yet")
 		return nil
 	}
+	if err != nil {
+		function.MarkDeployNotReady("DeployFailed", "Failed to check deployment status: %s", err.Error())
+		return fmt.Errorf("failed to check if function is already deployed: %w", err)
+	}
 
 	// function is deployed -> update status with metadata information
 	deployer := metadata.Deploy.Deployer
@@ -241,7 +241,7 @@ func (r *FunctionReconciler) reconcileDeployment(ctx context.Context, function *
 	applyLastDeployedAnnotation(ctx, function)
 
 	// Function is deployed - check middleware version
-	return r.handleMiddlewareUpdate(ctx, function, repo, metadata)
+	return r.handleMiddlewareUpdate(ctx, function, repo, metadata, &initialDesc)
 }
 
 // middlewareCheck is a sealed interface representing the result of inspecting a function's
@@ -279,12 +279,7 @@ type autoUpdateStatus struct {
 	source  string // "function" or "operator"
 }
 
-func (r *FunctionReconciler) checkMiddlewareState(ctx context.Context, function *v1alpha1.Function, metadata *funcfn.Function) (middlewareCheck, error) {
-	desc, err := r.FuncCliManager.Describe(ctx, metadata.Name, function.Namespace)
-	if err != nil {
-		return nil, fmt.Errorf("failed to describe function: %w", err)
-	}
-
+func (r *FunctionReconciler) checkMiddlewareState(ctx context.Context, function *v1alpha1.Function, metadata *funcfn.Function, desc *funcfn.Instance) (middlewareCheck, error) {
 	autoUpdate, err := r.getAutoUpdateStatus(ctx, function)
 	if err != nil {
 		return nil, fmt.Errorf("failed to check middleware update setting: %w", err)
@@ -326,10 +321,10 @@ func (r *FunctionReconciler) getAutoUpdateStatus(ctx context.Context, function *
 }
 
 // handleMiddlewareUpdate checks if the function is using the latest middleware and redeploys if needed
-func (r *FunctionReconciler) handleMiddlewareUpdate(ctx context.Context, function *v1alpha1.Function, repo *git.Repository, metadata *funcfn.Function) error {
+func (r *FunctionReconciler) handleMiddlewareUpdate(ctx context.Context, function *v1alpha1.Function, repo *git.Repository, metadata *funcfn.Function, desc *funcfn.Instance) error {
 	logger := log.FromContext(ctx)
 
-	check, err := r.checkMiddlewareState(ctx, function, metadata)
+	check, err := r.checkMiddlewareState(ctx, function, metadata, desc)
 	if err != nil {
 		function.MarkMiddlewareNotUpToDate("MiddlewareCheckFailed", "Failed to check middleware: %s", err)
 		return err
@@ -412,19 +407,6 @@ func markServiceStatus(ready string, function *v1alpha1.Function) {
 	}
 }
 
-func (r *FunctionReconciler) isDeployed(ctx context.Context, name, namespace string) (bool, error) {
-	_, err := r.FuncCliManager.Describe(ctx, name, namespace)
-	if err != nil {
-		if strings.Contains(err.Error(), "not found") || strings.Contains(err.Error(), "no describe function") {
-			return false, nil
-		}
-
-		return false, fmt.Errorf("failed to describe function: %w", err)
-	}
-
-	return true, nil
-}
-
 // SetupWithManager sets up the controller with the Manager.
 func (r *FunctionReconciler) SetupWithManager(mgr ctrl.Manager) error {
 	return ctrl.NewControllerManagedBy(mgr).

internal/funccli/manager.go

@@ -20,6 +20,8 @@ import (
 	funcfn "knative.dev/func/pkg/functions"
 )
 
+var ErrFunctionNotFound = fmt.Errorf("function not found")
+
 const (
 	githubAPIURL         = "https://api.github.com/repos/knative/func/releases/latest"
 	defaultCheckInterval = 5 * time.Minute
@@ -190,6 +192,9 @@ func (m *managerImpl) Run(ctx context.Context, dir string, args ...string) (stri
 func (m *managerImpl) Describe(ctx context.Context, name, namespace string) (funcfn.Instance, error) {
 	out, err := m.Run(ctx, "", "describe", "-n", namespace, "-o", "json", name)
 	if err != nil {
+		if strings.Contains(err.Error(), "not found") || strings.Contains(err.Error(), "no describe function") {
+			return funcfn.Instance{}, ErrFunctionNotFound
+		}
 		return funcfn.Instance{}, fmt.Errorf("failed to describe function: %q. %w", out, err)
 	}