OpenShift TLS Security Profile Configuration

OpenShift TLS Security Profile Configuration

This skill helps implement TLS security profiles for operators and workloads running on OpenShift. It provides complete guidance on reading TLS configuration from OpenShift cluster and applying it consistently across all secured endpoints.

Background

This skill implements the requirements defined in the Centralized and Enforced TLS Configuration Enhancement. The enhancement addresses the gap where many OpenShift components hardcode TLS settings or rely on library defaults rather than respecting cluster-wide TLS configuration. Key points:

• All components must honor the centralized TLS security profile from the cluster
• This enables consistent cryptographic policy enforcement and Post-Quantum Cryptography (PQC) readiness
• Do not hardcode TLS versions (e.g., TLS 1.3). Always read TLS settings dynamically.

The API changes are implemented in openshift/api#2680, which adds the TLSAdherence feature gate and tlsAdherence field to apiserver.config.openshift.io/v1.

TLS Adherence Modes

The tlsAdherence field in the APIServer CR controls how strictly components adhere to the configured TLS security profile:

Mode	Description
Legacy (default)	Backward-compatible behavior. Components attempt to honor the configured TLS profile but may fall back to their individual defaults if conflicts arise. Intended for clusters that need to maintain compatibility during migration.
Strict	Enforces strict adherence to the TLS configuration. All components must honor the configured profile without fallbacks. Recommended for security-conscious deployments and required for certain compliance frameworks.

Feature Gate: The TLSAdherence feature gate controls this functionality. It is currently enabled in DevPreviewNoUpgrade and TechPreviewNoUpgrade.

Implementation Note: When implementing TLS profile support in your operator, ensure your component works correctly in both modes. In Strict mode, components that fail to apply the configured TLS profile should report degraded status rather than silently falling back to defaults.

TLS Profile Sources

Default Source: API Server Configuration

Most components should use the API Server configuration as their TLS profile source. This is the default and preferred option. If you're unsure which source to use, start with the API Server configuration.

Order of Precedence (use only if you have a specific reason to deviate from API Server):

Source	When to Use
API Server (default)	Use this by default. Most OpenShift operators use library-go's apiserver config observer pattern, which automatically observes the API Server TLS profile.
Kubelet	Only use if your component is specifically running on the kubelet and needs to match kubelet's TLS settings.
Ingress Controller	Only use if your component is specifically handling ingress traffic and needs to match the ingress controller's TLS settings.

When to Use This Skill

Use this skill when:

• Implementing TLS security profiles in a Kubernetes operator running on OpenShift
• Configuring webhook servers and metrics endpoints with cluster-wide TLS settings
• Setting up HTTP or gRPC clients/servers that need to comply with OpenShift TLS policies
• Converting OpenShift TLS profile types to Go crypto/tls configuration

Requirements

Operators implementing TLS security profiles must satisfy these requirements:

1. Read TLS profile from APIServer CR: Fetch configuration from apiservers.config.openshift.io/cluster
2. Apply to all TLS endpoints: Webhook server, metrics server, and any HTTP/gRPC clients or servers
3. Respond to profile changes: If the TLS profile is updated in the cluster, the component must pick up the changes (existing connections should be terminated and new connections should use the new profile).

Handling Profile Changes

There are several approaches to respond to TLS profile changes:

Option A: Use controller-runtime-common Package (Recommended for controller-runtime)

For operators using controller-runtime, the recommended approach is to use the official package:

github.com/openshift/controller-runtime-common/pkg/tls

This package provides all necessary utilities for TLS profile implementation.

Quick Start Example:

package main

import (
	"context"
	"crypto/tls"
	"os"

	configv1 "github.com/openshift/api/config/v1"
	openshifttls "github.com/openshift/controller-runtime-common/pkg/tls"
	"sigs.k8s.io/controller-runtime/pkg/metrics/filters"
	"k8s.io/apimachinery/pkg/runtime"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
	"sigs.k8s.io/controller-runtime/pkg/webhook"
)

var scheme = runtime.NewScheme()

func init() {
	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
	utilruntime.Must(configv1.AddToScheme(scheme))
}

func main() {
	// Create a cancellable context for graceful shutdown on TLS profile changes
	ctx, cancel := context.WithCancel(ctrl.SetupSignalHandler())
	defer cancel()

	cfg := ctrl.GetConfigOrDie()

	// Create a temporary client to fetch initial TLS profile
	tempClient, err := client.New(cfg, client.Options{Scheme: scheme})
	if err != nil {
		os.Exit(1)
	}

	// Fetch the TLS profile from APIServer CR
	tlsProfileSpec, err := openshifttls.FetchAPIServerTLSProfile(ctx, tempClient)
	if err != nil {
		os.Exit(1)
	}

	// Convert to TLSOpts function for controller-runtime
	tlsOpts, unsupportedCiphers := openshifttls.NewTLSConfigFromProfile(tlsProfileSpec)
	if len(unsupportedCiphers) > 0 {
		// Log warning about unsupported ciphers
	}

	mgr, err := ctrl.NewManager(cfg, ctrl.Options{
		Scheme: scheme,
		Metrics: metricsserver.Options{
			BindAddress:   ":8443",
			SecureServing: true,
			FilterProvider: filters.WithAuthenticationAndAuthorization,
			TLSOpts:       []func(*tls.Config){tlsOpts},
		},
		WebhookServer: webhook.NewServer(webhook.Options{
			Port:    9443,
			TLSOpts: []func(*tls.Config){tlsOpts},
		}),
	})
	if err != nil {
		os.Exit(1)
	}

	// Set up the TLS profile watcher to trigger graceful shutdown on changes
	watcher := &openshifttls.SecurityProfileWatcher{
		Client:                mgr.GetClient(),
		InitialTLSProfileSpec: tlsProfileSpec,
		OnProfileChange: func(ctx context.Context, old, new configv1.TLSProfileSpec) {
			// Cancel context to trigger graceful shutdown and reload
			cancel()
		},
	}
	if err := watcher.SetupWithManager(mgr); err != nil {
		os.Exit(1)
	}

	if err := mgr.Start(ctx); err != nil {
		os.Exit(1)
	}
}

Package Functions:

Function	Purpose
FetchAPIServerTLSProfile(ctx, client)	Fetches TLS profile spec from APIServer CR, returns default (Intermediate) if not set
GetTLSProfileSpec(profile)	Resolves profile type (Old/Intermediate/Modern/Custom) to TLSProfileSpec
NewTLSConfigFromProfile(spec)	Returns a func(*tls.Config) for controller-runtime's TLSOpts + list of unsupported ciphers
SecurityProfileWatcher	Controller that watches APIServer and triggers callback on TLS profile changes

SecurityProfileWatcher:

The SecurityProfileWatcher is a controller that watches the APIServer CR and invokes a callback when the TLS profile changes:

watcher := &openshifttls.SecurityProfileWatcher{
	Client:                mgr.GetClient(),
	InitialTLSProfileSpec: initialProfile,
	OnProfileChange: func(ctx context.Context, old, new configv1.TLSProfileSpec) {
		// Common pattern: cancel context to trigger graceful shutdown
		// The operator will restart and pick up the new TLS configuration
		cancel()
	},
}
if err := watcher.SetupWithManager(mgr); err != nil {
	return err
}

Note: The watcher handles predicates internally - it only watches the "cluster" APIServer object and compares profile changes using reflect.DeepEqual.

Restart vs Hot-Reload Trade-offs:

Approach	Restart Required	Existing Connections	Recommendation
SecurityProfileWatcher	Yes - graceful shutdown	All connections use new TLS settings after restart	Recommended - ensures consistent TLS policy across all connections
GetConfigForClient (Option D)	No	Not updated - only new connections use new settings	Use only when restarts are not acceptable

Why SecurityProfileWatcher is recommended:

• TLS profile changes are cluster-level security policy changes that should apply uniformly
• GetConfigForClient leaves existing long-lived connections using the old TLS configuration
• Graceful shutdown ensures all connections are re-established with the correct TLS settings
• Simpler implementation using the official package

Option B: For OpenShift Operators (configobserver pattern)

This is the recommended approach for OpenShift operators using the library-go configobserver pattern. Use library-go's ObserveTLSSecurityProfile function from the apiserver config observer package. This function:

• Observes the API Server's TLSSecurityProfile from the cluster configuration (via APIServerLister().Get("cluster")) - this is the default source for all components
• Converts OpenSSL cipher names to IANA names (used by Kubernetes ServingInfo configuration) using crypto.OpenSSLToIANACipherSuites
• Sets servingInfo.minTLSVersion and servingInfo.cipherSuites in the observed config
• Returns the configuration as a map[string]interface{} in the format expected by your operator's observed config
• Centralizes profile mappings in library-go to ensure all components use consistent TLS profile handling

package configobserver

import (
	"github.com/openshift/library-go/pkg/operator/configobserver"
	"github.com/openshift/library-go/pkg/operator/configobserver/apiserver"
	"github.com/openshift/library-go/pkg/operator/events"
)

// In your config observer controller's ObserveConfig method
func (c *MyConfigObserver) ObserveConfig(
	listers configobserver.Listers,
	recorder events.Recorder,
	existingConfig map[string]interface{},
) (map[string]interface{}, []error) {
	// ObserveTLSSecurityProfile observes APIServer.Spec.TLSSecurityProfile and sets
	// servingInfo.minTLSVersion and servingInfo.cipherSuites in observedConfig
	observedConfig, errs := apiserver.ObserveTLSSecurityProfile(listers, recorder, existingConfig)
	// ... merge with other observed config
	return observedConfig, errs
}

Option C: Watch from Existing Controller

If your operator cannot use the SecurityProfileWatcher (Option A) or the configobserver pattern (Option B), use this approach. Watch the APIServer resource from your existing controller to trigger operand reconciliation when the TLS profile changes, allowing you to update operand deployments with the new TLS settings:

package controller

import (
	"context"
	"reflect"

	configv1 "github.com/openshift/api/config/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/builder"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/event"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	myv1 "myoperator/api/v1"
)

type MyOperandReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

func (r *MyOperandReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	// Fetch operand
	operand := &myv1.MyOperand{}
	if err := r.Get(ctx, req.NamespacedName, operand); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	// Fetch current TLS profile
	profile, err := GetTLSSecurityProfile(ctx, r.Client)
	if err != nil {
		return ctrl.Result{}, err
	}

	// Apply TLS configuration to operand's deployment/pods
	// This could involve updating a ConfigMap, Secret, or Deployment annotation
	// to trigger a rolling restart of operand pods with new TLS settings
	if err := r.reconcileOperandTLS(ctx, operand, profile); err != nil {
		return ctrl.Result{}, err
	}

	return ctrl.Result{}, nil
}

func (r *MyOperandReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&myv1.MyOperand{}).
		// Watch APIServer and trigger reconcile for all operands when TLS profile changes
		Watches(
			&configv1.APIServer{},
			handler.EnqueueRequestsFromMapFunc(r.mapAPIServerToOperands),
			builder.WithPredicates(tlsProfileChangedPredicate()),
		).
		Complete(r)
}

// mapAPIServerToOperands returns reconcile requests for all operands when APIServer changes
func (r *MyOperandReconciler) mapAPIServerToOperands(ctx context.Context, obj client.Object) []reconcile.Request {
	// Only react to the "cluster" APIServer
	if obj.GetName() != "cluster" {
		return nil
	}

	// List all operands and trigger reconcile for each
	var operands myv1.MyOperandList
	if err := r.List(ctx, &operands); err != nil {
		return nil
	}

	requests := make([]reconcile.Request, len(operands.Items))
	for i, op := range operands.Items {
		requests[i] = reconcile.Request{
			NamespacedName: types.NamespacedName{
				Name:      op.Name,
				Namespace: op.Namespace,
			},
		}
	}
	return requests
}

// tlsProfileChangedPredicate filters events to only TLS profile changes
func tlsProfileChangedPredicate() predicate.Predicate {
	return predicate.Funcs{
		CreateFunc: func(e event.CreateEvent) bool {
			return e.Object.GetName() == "cluster"
		},
		UpdateFunc: func(e event.UpdateEvent) bool {
			if e.ObjectNew.GetName() != "cluster" {
				return false
			}
			oldAPI, ok := e.ObjectOld.(*configv1.APIServer)
			if !ok {
				return false
			}
			newAPI, ok := e.ObjectNew.(*configv1.APIServer)
			if !ok {
				return false
			}
			// Only reconcile if TLS profile actually changed
			return !reflect.DeepEqual(
				oldAPI.Spec.TLSSecurityProfile,
				newAPI.Spec.TLSSecurityProfile,
			)
		},
		DeleteFunc: func(e event.DeleteEvent) bool {
			return false
		},
		GenericFunc: func(e event.GenericEvent) bool {
			return false
		},
	}
}

func (r *MyOperandReconciler) reconcileOperandTLS(
	ctx context.Context,
	operand *myv1.MyOperand,
	profile *configv1.TLSSecurityProfile,
) error {
	// Update operand deployment with new TLS settings
	// For example, update an annotation to trigger rolling restart:
	//
	// deployment.Spec.Template.Annotations["tls-profile-hash"] = hashTLSProfile(profile)
	//
	// Or update a ConfigMap/Secret that the operand mounts
	return nil
}

This approach is efficient because:

• Uses predicates to filter only TLS profile changes (ignores other APIServer updates)
• Integrates with existing controller logic
• Automatically reconciles all operands when the profile changes
• Follows standard controller-runtime patterns

Option D: Dynamic TLS Config Update (Not Recommended)

An alternative approach uses Go's GetConfigForClient callback to dynamically return TLS configuration for each new connection without requiring a restart. However, this approach is not recommended because:

• Existing connections are not affected - they continue using the old TLS configuration until they disconnect
• Long-lived connections may remain on outdated TLS settings indefinitely
• TLS profile changes are security policy changes that should apply uniformly to all connections

For consistent TLS policy enforcement, use Option A (SecurityProfileWatcher with graceful restart) or Option C (watch and reconcile) instead.

Implementation Steps

Step 1: Fetch TLS Profile from APIServer CR

Use FetchAPIServerTLSProfile from the controller-runtime-common package to retrieve the TLS security profile:

import (
	openshifttls "github.com/openshift/controller-runtime-common/pkg/tls"
)

// Fetch the TLS profile from APIServer CR
// Returns default Intermediate profile if not set
tlsProfileSpec, err := openshifttls.FetchAPIServerTLSProfile(ctx, client)
if err != nil {
	return err
}

This function fetches the TLSSecurityProfile from apiservers.config.openshift.io/cluster and returns the default Intermediate profile if none is configured.

Step 2: Convert TLS Profile to Go crypto/tls Configuration

Use NewTLSConfigFromProfile from the controller-runtime-common package to convert the TLS profile spec to a func(*tls.Config) suitable for controller-runtime:

import (
	openshifttls "github.com/openshift/controller-runtime-common/pkg/tls"
)

// Convert to TLSOpts function for controller-runtime
// Returns a func(*tls.Config) that sets MinVersion and CipherSuites
tlsOpts, unsupportedCiphers := openshifttls.NewTLSConfigFromProfile(tlsProfileSpec)
if len(unsupportedCiphers) > 0 {
	// Log warning about unsupported ciphers (ciphers not available in Go's crypto/tls)
	log.Info("Some ciphers from TLS profile are not supported", "ciphers", unsupportedCiphers)
}

This function handles:

• Resolving profile types (Old/Intermediate/Modern/Custom) to their cipher suites and min TLS version
• Converting OpenSSL cipher names to Go crypto/tls constants
• Returning unsupported ciphers for logging (some OpenSSL ciphers have no Go equivalent)

Step 3: Apply to All HTTP and gRPC Clients/Servers

For controller-runtime webhook and metrics servers, see the complete Quick Start Example in Option A above.

For other endpoints:

All TLS-enabled endpoints in your operator and operand must honor the cluster TLS configuration. This includes:

Endpoint Type	How to Apply TLS Config
HTTP Client	Set Transport.TLSClientConfig on http.Client
HTTP Server	Set TLSConfig on http.Server
gRPC Client	Use grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)) with grpc.NewClient()
gRPC Server	Use grpc.Creds(credentials.NewTLS(tlsConfig)) with grpc.NewServer()

For each endpoint, use the *tls.Config returned by TLSConfigFromProfile() (Step 2) to configure:

• MinVersion - minimum TLS protocol version
• CipherSuites - allowed cipher suites (only applies to TLS 1.2 and below)

Key principle: No HTTP or gRPC endpoint should use hardcoded TLS settings. Always derive TLS configuration from the cluster's APIServer CR to ensure consistent security policy enforcement across all components.

TLS Profile Types

OpenShift supports four TLS profile types based on Mozilla's Server Side TLS recommendations:

Profile	Min TLS Version	Description
Old	TLS 1.0	Legacy compatibility, not recommended for production
Intermediate (default)	TLS 1.2	Recommended for general use, balances security and compatibility
Modern	TLS 1.3	Highest security, may not work with older clients
Custom	Configurable	User-defined ciphers and minimum TLS version

Default Profile: When spec.tlsSecurityProfile is not set in the APIServer CR, the Intermediate profile is used as the default. This provides a good balance between security and compatibility.

Note: In Go, cipher suites are not configurable for TLS 1.3 - they are automatically selected by the runtime.

APIServer Custom Resource

The TLS profile is configured in the APIServer custom resource named cluster. If spec.tlsSecurityProfile is not specified, the Intermediate profile is used by default.

apiVersion: config.openshift.io/v1
kind: APIServer
metadata:
  name: cluster
spec:
  audit:
    profile: Default
  # tlsSecurityProfile is optional. If not set, defaults to Intermediate profile.
  tlsSecurityProfile:
    # type can be: Old, Intermediate, Modern, or Custom
    type: Intermediate
    # Only one of the following should be set based on type:
    old: {}
    intermediate: {}
    modern: {}
    custom:
      ciphers:
        - TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
        - TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
      minTLSVersion: VersionTLS12

Reference:

• APIServer Config API Reference
• APIServer CR Spec Example
• TLSSecurityProfile Type Definition

Query Commands

Check the current TLS security profile in your cluster:

# Get the full APIServer configuration
oc get apiserver cluster -o yaml

# Get just the TLS security profile (empty output means default Intermediate profile is used)
oc get apiserver cluster -o jsonpath='{.spec.tlsSecurityProfile}' | jq .

# Check the effective TLS profile type (empty means Intermediate default)
oc get apiserver cluster -o jsonpath='{.spec.tlsSecurityProfile.type}'

Note: If the above commands return empty output, the cluster is using the default Intermediate profile.

OpenShift library-go Crypto Utilities

Note: For controller-runtime users, NewTLSConfigFromProfile from github.com/openshift/controller-runtime-common/pkg/tls handles all cipher conversion automatically. The utilities below are primarily for:

• Non-controller-runtime code (e.g., library-go based operators using configobserver pattern)
• Understanding how the conversion works internally

The github.com/openshift/library-go/pkg/crypto package provides utilities for converting between OpenShift TLS profile configurations and Go's crypto/tls types:

Function	Purpose
TLSVersion(name string) (uint16, error)	Convert TLS version name (e.g., "VersionTLS12") to Go constant
CipherSuitesOrDie(names []string) []uint16	Convert IANA cipher names to Go constants
OpenSSLToIANACipherSuites(ciphers []string) []string	Map OpenSSL cipher names to IANA names
SecureTLSConfig(config *tls.Config) *tls.Config	Apply secure defaults to a TLS config
DefaultCiphers() []uint16	Get default cipher suites for Intermediate profile

Why these exist: OpenShift's configv1.TLSProfiles uses OpenSSL-format cipher names, not Go constants. These utilities handle the conversion.

Additional Resources

• OpenShift controller-runtime-common TLS Package - Recommended package for controller-runtime operators
• OpenShift TLS Security Profiles Documentation
• Mozilla Server Side TLS
• OpenShift API Types - TLS Security Profile
• TLSSecurityProfile Type Definition
• APIServer Config API Reference
• APIServer CR Spec Example
• OpenShift library-go Crypto Package
• Go crypto/tls Package
• controller-runtime Webhook Server
• TLS Configuration in OpenShift
• TLS Adherence