WIP: Add developer hints

pkg/hints/log.go

@@ -0,0 +1,33 @@
+package hints
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"k8s.io/klog/v2"
+)
+
+// EnvRecommendationsAreStrict is the environment variable that can be set
+// to make developer recommendations a panic.  It can be set by developers
+// while developing to help them keep up with changes to
+// kubebuilder-declarative-pattern and any upstream changes.
+const EnvRecommendationsAreStrict = "FAIL_ON_DEVELOPER_RECOMMENDATIONS"
+
+// DeveloperRecommendation will log a recommendation for developers;
+// helping developers keep up with changes here and upstream.
+// If EnvRecommendationsAreStrict is set, we will panic.
+func DeveloperRecommendation(ctx context.Context, msg string, keysAndValues ...any) {
+	log := klog.FromContext(ctx)
+	log.Info(msg, keysAndValues...)
+	if os.Getenv(EnvRecommendationsAreStrict) != "" {
+		s := fmt.Sprintf("recommendation for developers with %s environment variable set, so treating as a failure: %s", EnvRecommendationsAreStrict, msg)
+		for i := 0; (i + 1) < len(keysAndValues); i++ {
+			if i != 0 {
+				s += ", "
+			}
+			s += fmt.Sprintf("%v:%v", keysAndValues[i], keysAndValues[i+1])
+		}
+		panic(s)
+	}
+}

pkg/patterns/declarative/pkg/applier/applylib.go

@@ -12,6 +12,7 @@ import (
 	"k8s.io/client-go/dynamic"
 	"k8s.io/klog/v2"
 	"sigs.k8s.io/kubebuilder-declarative-pattern/applylib/applyset"
+	"sigs.k8s.io/kubebuilder-declarative-pattern/pkg/hints"
 )
 
 type ApplysetOptions struct {
@@ -57,6 +58,7 @@ func (a *ApplySetApplier) Apply(ctx context.Context, opt ApplierOptions) error {
 
 	dynamicClient := opt.DynamicClient
 	if dynamicClient == nil {
+		hints.DeveloperRecommendation(context.Background(), "consider setting ApplierOptions.DynamicClient", "applierOptions", opt)
 		d, err := dynamic.NewForConfig(opt.RESTConfig)
 		if err != nil {
 			return fmt.Errorf("error building dynamic client: %w", err)

pkg/patterns/declarative/watch.go

@@ -33,6 +33,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/source"
 	"sigs.k8s.io/kubebuilder-declarative-pattern/commonclient"
+	"sigs.k8s.io/kubebuilder-declarative-pattern/pkg/hints"
 	"sigs.k8s.io/kubebuilder-declarative-pattern/pkg/patterns/declarative/pkg/watch"
 )
 
@@ -55,6 +56,9 @@ type WatchChildrenOptions struct {
 	// RESTConfig is the configuration for connecting to the cluster.
 	RESTConfig *rest.Config
 
+	// HTTPClient is the HTTP client to use for requests.
+	HTTPClient *http.Client
+
 	// LabelMaker is used to build the labels we should watch on.
 	LabelMaker LabelMaker
 
@@ -88,6 +92,22 @@ func WatchChildren(options WatchChildrenOptions) error {
 		return fmt.Errorf("labelMaker is required to scope watches")
 	}
 
+	var httpClient *http.Client
+	if options.HTTPClient != nil {
+		httpClient = options.HTTPClient
+	} else {
+		if options.RESTConfig != nil {
+			hints.DeveloperRecommendation(context.Background(), "consider setting WatchChildrenOptions.HTTPClient, if setting RESTConfig", "options", options)
+			hc, err := rest.HTTPClientFor(options.RESTConfig)
+			if err != nil {
+				return err
+			}
+			httpClient = hc
+		} else if options.Manager != nil {
+			httpClient = options.Manager.GetHTTPClient()
+		}
+	}
+
 	if options.RESTConfig == nil {
 		if options.Manager != nil {
 			options.RESTConfig = options.Manager.GetConfig()
@@ -100,23 +120,19 @@ func WatchChildren(options WatchChildrenOptions) error {
 	if options.Manager != nil {
 		restMapper = options.Manager.GetRESTMapper()
 	} else {
-		client, err := rest.HTTPClientFor(options.RESTConfig)
-		if err != nil {
-			return err
-		}
-		rm, err := commonclient.NewDiscoveryRESTMapper(options.RESTConfig, client)
+		rm, err := commonclient.NewDiscoveryRESTMapper(options.RESTConfig, httpClient)
 		if err != nil {
 			return err
 		}
 		restMapper = rm
 	}
 
-	client, err := dynamic.NewForConfig(options.RESTConfig)
+	dynamicClient, err := dynamic.NewForConfigAndClient(options.RESTConfig, httpClient)
 	if err != nil {
 		return err
 	}
 
-	dw, events, err := watch.NewDynamicWatch(restMapper, client)
+	dw, events, err := watch.NewDynamicWatch(restMapper, dynamicClient)
 	if err != nil {
 		return fmt.Errorf("creating dynamic watch: %v", err)
 	}