Add aggregatedAPIServerPort to the Concierge's static ConfigMap

- Allow the port number to be configured to any value within the
  range 1024 to 65535
- This commit does not include adding new config knobs to the ytt
  values file, so while it is possible to change this port without
  needing to recompile, it is not convenient

Dockerfile

@@ -29,8 +29,8 @@ FROM gcr.io/distroless/static:nonroot@sha256:bca3c203cdb36f5914ab8568e4c25165643
 # Copy the server binary from the build-env stage.
 COPY --from=build-env /usr/local/bin /usr/local/bin
 
-# Document the ports
-EXPOSE 8080 8443
+# Document the default server ports for the various server apps
+EXPOSE 8080 8443 8444 10250
 
 # Run as non-root for security posture
 # Use the same non-root user as https://github.com/GoogleContainerTools/distroless/blob/fc3c4eaceb0518900f886aae90407c43be0a42d9/base/base.bzl#L9

deploy/concierge/deployment.yaml

@@ -58,6 +58,7 @@ data:
         durationSeconds: (@= str(data.values.api_serving_certificate_duration_seconds) @)
         renewBeforeSeconds: (@= str(data.values.api_serving_certificate_renew_before_seconds) @)
     apiGroupSuffix: (@= data.values.api_group_suffix @)
+    # aggregatedAPIServerPort may be set here, although other YAML references to the default port (10250) may also need to be updated
     names:
       servingCertificateSecret: (@= defaultResourceNameWithSuffix("api-tls-serving-certificate") @)
       credentialIssuer: (@= defaultResourceNameWithSuffix("config") @)
@@ -175,7 +176,7 @@ spec:
           livenessProbe:
             httpGet:
               path: /healthz
-              port: 8443
+              port: 10250
               scheme: HTTPS
             initialDelaySeconds: 2
             timeoutSeconds: 15
@@ -184,7 +185,7 @@ spec:
           readinessProbe:
             httpGet:
               path: /healthz
-              port: 8443
+              port: 10250
               scheme: HTTPS
             initialDelaySeconds: 2
             timeoutSeconds: 3
@@ -251,7 +252,7 @@ spec:
   ports:
     - protocol: TCP
       port: 443
-      targetPort: 8443
+      targetPort: 10250
 ---
 apiVersion: v1
 kind: Service

deploy/concierge/values.yaml

@@ -41,7 +41,7 @@ kube_cert_agent_image:
 image_pull_dockerconfigjson: #! e.g. {"auths":{"https://registry.example.com":{"username":"USERNAME","password":"PASSWORD","auth":"BASE64_ENCODED_USERNAME_COLON_PASSWORD"}}}
 
 #! Pinniped will try to guess the right K8s API URL for sharing that information with potential clients.
-#! This settings allows the guess to be overridden.
+#! This setting allows the guess to be overridden.
 #! Optional.
 discovery_url: #! e.g., https://example.com
 

internal/concierge/server/server.go

@@ -168,6 +168,7 @@ func (a *App) runServer(ctx context.Context) error {
 		certIssuer,
 		buildControllers,
 		*cfg.APIGroupSuffix,
+		*cfg.AggregatedAPIServerPort,
 		scheme,
 		loginGV,
 		identityGV,
@@ -193,6 +194,7 @@ func getAggregatedAPIServerConfig(
 	issuer issuer.ClientCertIssuer,
 	buildControllers controllerinit.RunnerBuilder,
 	apiGroupSuffix string,
+	aggregatedAPIServerPort int64,
 	scheme *runtime.Scheme,
 	loginConciergeGroupVersion, identityConciergeGroupVersion schema.GroupVersion,
 ) (*apiserver.Config, error) {
@@ -207,7 +209,9 @@ func getAggregatedAPIServerConfig(
 	)
 	recommendedOptions.Etcd = nil // turn off etcd storage because we don't need it yet
 	recommendedOptions.SecureServing.ServerCert.GeneratedCert = dynamicCertProvider
-	recommendedOptions.SecureServing.BindPort = 8443 // Don't run on default 443 because that requires root
+
+	// This port is configurable. It should be safe to cast because the config reader already validated it.
+	recommendedOptions.SecureServing.BindPort = int(aggregatedAPIServerPort)
 
 	serverConfig := genericapiserver.NewRecommendedConfig(codecs)
 	// Note that among other things, this ApplyTo() function copies

internal/config/concierge/config.go

@@ -21,6 +21,12 @@ import (
 const (
 	aboutAYear   = 60 * 60 * 24 * 365
 	about9Months = 60 * 60 * 24 * 30 * 9
+
+	// Use 10250 because it happens to be the same port on which the Kubelet listens, so some cluster types
+	// are more permissive with servers that run on this port. For example, GKE private clusters do not
+	// allow traffic from the control plane to most ports, but do allow traffic to port 10250. This allows
+	// the Concierge to work without additional configuration on these types of clusters.
+	aggregatedAPIServerPortDefault = 10250
 )
 
 // FromPath loads an Config from a provided local file path, inserts any
@@ -42,6 +48,7 @@ func FromPath(path string) (*Config, error) {
 	}
 
 	maybeSetAPIDefaults(&config.APIConfig)
+	maybeSetAggregatedAPIServerPortDefaults(&config.AggregatedAPIServerPort)
 	maybeSetAPIGroupSuffixDefault(&config.APIGroupSuffix)
 	maybeSetKubeCertAgentDefaults(&config.KubeCertAgentConfig)
 
@@ -53,6 +60,10 @@ func FromPath(path string) (*Config, error) {
 		return nil, fmt.Errorf("validate apiGroupSuffix: %w", err)
 	}
 
+	if err := validateAggregatedAPIServerPort(config.AggregatedAPIServerPort); err != nil {
+		return nil, fmt.Errorf("validate aggregatedAPIServerPort: %w", err)
+	}
+
 	if err := validateNames(&config.NamesConfig); err != nil {
 		return nil, fmt.Errorf("validate names: %w", err)
 	}
@@ -84,6 +95,12 @@ func maybeSetAPIGroupSuffixDefault(apiGroupSuffix **string) {
 	}
 }
 
+func maybeSetAggregatedAPIServerPortDefaults(aggregatedAPIServerPort **int64) {
+	if *aggregatedAPIServerPort == nil {
+		*aggregatedAPIServerPort = pointer.Int64Ptr(aggregatedAPIServerPortDefault)
+	}
+}
+
 func maybeSetKubeCertAgentDefaults(cfg *KubeCertAgentSpec) {
 	if cfg.NamePrefix == nil {
 		cfg.NamePrefix = pointer.StringPtr("pinniped-kube-cert-agent-")
@@ -147,3 +164,11 @@ func validateAPI(apiConfig *APIConfigSpec) error {
 func validateAPIGroupSuffix(apiGroupSuffix string) error {
 	return groupsuffix.Validate(apiGroupSuffix)
 }
+
+func validateAggregatedAPIServerPort(aggregatedAPIServerPort *int64) error {
+	// It cannot be below 1024 because the container is not running as root.
+	if *aggregatedAPIServerPort < 1024 || *aggregatedAPIServerPort > 65535 {
+		return constable.Error("must be within range 1024 to 65535")
+	}
+	return nil
+}

internal/config/concierge/config_test.go

@@ -33,6 +33,7 @@ func TestFromPath(t *testing.T) {
 					durationSeconds: 3600
 					renewBeforeSeconds: 2400
 				apiGroupSuffix: some.suffix.com
+				aggregatedAPIServerPort: 12345
 				names:
 				  servingCertificateSecret: pinniped-concierge-api-tls-serving-certificate
 				  credentialIssuer: pinniped-config
@@ -65,7 +66,8 @@ func TestFromPath(t *testing.T) {
 						RenewBeforeSeconds: pointer.Int64Ptr(2400),
 					},
 				},
-				APIGroupSuffix: pointer.StringPtr("some.suffix.com"),
+				APIGroupSuffix:          pointer.StringPtr("some.suffix.com"),
+				AggregatedAPIServerPort: pointer.Int64Ptr(12345),
 				NamesConfig: NamesConfigSpec{
 					ServingCertificateSecret:          "pinniped-concierge-api-tls-serving-certificate",
 					CredentialIssuer:                  "pinniped-config",
@@ -108,7 +110,8 @@ func TestFromPath(t *testing.T) {
 				DiscoveryInfo: DiscoveryInfoSpec{
 					URL: nil,
 				},
-				APIGroupSuffix: pointer.StringPtr("pinniped.dev"),
+				APIGroupSuffix:          pointer.StringPtr("pinniped.dev"),
+				AggregatedAPIServerPort: pointer.Int64Ptr(10250),
 				APIConfig: APIConfigSpec{
 					ServingCertificateConfig: ServingCertificateConfigSpec{
 						DurationSeconds:    pointer.Int64Ptr(60 * 60 * 24 * 365),    // about a year
@@ -323,6 +326,22 @@ func TestFromPath(t *testing.T) {
 			`),
 			wantError: "validate api: renewBefore must be positive",
 		},
+		{
+			name: "AggregatedAPIServerPortDefault too small",
+			yaml: here.Doc(`
+				---
+				aggregatedAPIServerPort: 1023
+			`),
+			wantError: "validate aggregatedAPIServerPort: must be within range 1024 to 65535",
+		},
+		{
+			name: "AggregatedAPIServerPortDefault too large",
+			yaml: here.Doc(`
+				---
+				aggregatedAPIServerPort: 65536
+			`),
+			wantError: "validate aggregatedAPIServerPort: must be within range 1024 to 65535",
+		},
 		{
 			name: "ZeroRenewBefore",
 			yaml: here.Doc(`

internal/config/concierge/types.go

@@ -7,13 +7,14 @@ import "go.pinniped.dev/internal/plog"
 
 // Config contains knobs to setup an instance of the Pinniped Concierge.
 type Config struct {
-	DiscoveryInfo       DiscoveryInfoSpec `json:"discovery"`
-	APIConfig           APIConfigSpec     `json:"api"`
-	APIGroupSuffix      *string           `json:"apiGroupSuffix,omitempty"`
-	NamesConfig         NamesConfigSpec   `json:"names"`
-	KubeCertAgentConfig KubeCertAgentSpec `json:"kubeCertAgent"`
-	Labels              map[string]string `json:"labels"`
-	LogLevel            plog.LogLevel     `json:"logLevel"`
+	DiscoveryInfo           DiscoveryInfoSpec `json:"discovery"`
+	APIConfig               APIConfigSpec     `json:"api"`
+	APIGroupSuffix          *string           `json:"apiGroupSuffix,omitempty"`
+	AggregatedAPIServerPort *int64            `json:"aggregatedAPIServerPort"`
+	NamesConfig             NamesConfigSpec   `json:"names"`
+	KubeCertAgentConfig     KubeCertAgentSpec `json:"kubeCertAgent"`
+	Labels                  map[string]string `json:"labels"`
+	LogLevel                plog.LogLevel     `json:"logLevel"`
 }
 
 // DiscoveryInfoSpec contains configuration knobs specific to