now inferring the service accounts from the network policy config.

cmd/policygen/config.go

@@ -31,6 +31,7 @@ func (c *CIDR) UnmarshalYAML(value []byte) error {
 		return err
 	}
 	*c = CIDR(s)
+
 	return nil
 }
 
@@ -65,6 +66,7 @@ type Application struct {
 	MatchLabels map[string]string `yaml:"matchLabels"`
 	//MatchExpressions []MatchExpression `yaml:"matchExpressions" validate:"omitempty,dive"`
 	MatchExpressions []metav1.LabelSelectorRequirement `yaml:"matchExpressions" validate:"omitempty,dive"`
+	ServiceAccounts  []string                          `yaml:"serviceAccounts,omitempty"`
 	Namespace        *Namespace                        `yaml:"-" validate:"-"`
 }
 
@@ -171,6 +173,16 @@ func (c Config) GetApplication(name string) (*Application, *Network, string) {
 	return nil, nil, ""
 }
 
+func (c *Config) Infer(resolver func(application *Application) []string) {
+	for _, ns := range c.Namespaces {
+		for _, app := range ns.Applications {
+			if len(app.ServiceAccounts) == 0 {
+				app.ServiceAccounts = resolver(app)
+			}
+		}
+	}
+}
+
 func LoadConfig(file string) (*Config, error) {
 	fmt.Fprintf(os.Stderr, "Reading config %s\n", file)
 	yamlFile, err := os.ReadFile(file)

cmd/policygen/configvalidator.go

@@ -10,6 +10,7 @@ import (
 	"log"
 	"maps"
 	"os"
+	"slices"
 	"strconv"
 )
 
@@ -38,11 +39,28 @@ func MapKeys[K comparable, V any](m map[K]V) []K {
 }
 
 func validate(files []string, options *Options) error {
+	clientset, _ := GetKubernetesConnection()
 	config, err := readConfig(files)
 	if err != nil {
 		return err
 	}
-	clientset, _ := GetKubernetesConnection()
+	config.Infer(func(application *Application) []string {
+		pods := FindPods(application, clientset)
+		var res []string
+		for _, pod := range pods {
+			if !slices.Contains(res, pod.Spec.ServiceAccountName) {
+				res = append(res, pod.Spec.ServiceAccountName)
+			}
+		}
+		log.Printf("Inferred service accounts: %s/%s: %v", application.Namespace.Name, application.Name,
+			res)
+		return res
+	})
+
+	// map  applname1 -> appname2 where appname1 is in an open namespace and app2 is in a closed namespace.
+	openToClosedAccess := make(map[string]string)
+
+	applicationPods := make(map[string][]v1.Pod)
 	for _, ns := range config.Namespaces {
 		namespace := ns.Name
 		_, err = clientset.CoreV1().Namespaces().Get(context.Background(), namespace, metav1.GetOptions{})
@@ -50,8 +68,14 @@ func validate(files []string, options *Options) error {
 			LogValidationMsg(Error, "ERROR: namespace not found: %s", namespace)
 			continue
 		}
+
+		// checking for service accounts shared by applications
+		// map of namespace/sa -> []applicationname
+		serviceAccountMap := make(map[string][]string)
+
 		for _, application := range ns.Applications {
 			pods := FindPods(application, clientset)
+			applicationPods[application.Name] = pods
 			//log.Printf(namespace + "/" + application.Name)
 			if len(pods) == 0 {
 				LogValidationMsg(Error, "application %s: no running pods found", application.Name)
@@ -76,9 +100,47 @@ func validate(files []string, options *Options) error {
 				}
 			}
 			// Check service accounts
+			applicationServiceAccounts := make(map[string]bool)
+			for _, sa := range application.ServiceAccounts {
+				applicationServiceAccounts[sa] = true
+			}
+			for _, pod := range pods {
+				delete(applicationServiceAccounts, pod.Spec.ServiceAccountName)
+			}
+			if len(applicationServiceAccounts) > 0 {
+				LogValidationMsg(Error, "application %s: service accounts %v configured but not used by workloads",
+					application.Name, MapKeys(applicationServiceAccounts))
+			}
+			for _, pod := range pods {
+				sa := pod.Namespace + "/" + pod.Spec.ServiceAccountName
+				serviceAccountMap[sa] = append(serviceAccountMap[sa],
+					application.Name)
 
+				if pod.Spec.ServiceAccountName == "default" {
+					LogValidationMsg(Warning, "Pod %s/%s: running with default service account",
+						pod.Namespace, pod.Name)
+					if application.ServiceAccounts != nil && !slices.Contains(application.ServiceAccounts, "default") {
+						LogValidationMsg(Warning, "application %s: Pod %s/%s: running with 'default' service account but configured with %v",
+							application.Name, pod.Namespace, pod.Name, application.ServiceAccounts)
+					}
+				} else {
+					if !slices.Contains(application.ServiceAccounts, pod.Spec.ServiceAccountName) {
+						LogValidationMsg(Warning, "application %s: Pod %s/%s: running with service account '%s' but configured with %v",
+							application.Name, pod.Namespace, pod.Name, pod.Spec.ServiceAccountName, application.ServiceAccounts)
 					}
 				}
+			}
+		}
+
+		// service accounts shared by multiple applications.
+		for sa, applist := range serviceAccountMap {
+			if len(applist) == 1 {
+				continue
+			}
+			LogValidationMsg(Error, "service account %s: shared by multiple applications %v", sa, applist)
+		}
+	}
+
 	for _, communication := range config.Communications {
 		if len(communication.Ports) == 0 {
 			continue
@@ -99,7 +161,42 @@ func validate(files []string, options *Options) error {
 
 			}
 		}
+		for _, communication := range config.Communications {
+			for _, applicationName := range communication.To {
+				application, _, _ := config.GetApplication(applicationName)
+				if application == nil {
+					continue
 				}
+				// capability linkerd must exist on target namespace
+				if !slices.Contains(application.Namespace.Capabilities, "linkerd") {
+					continue
+				}
+				// annotation linkerd.io/inject must not be disabled
+				pods := applicationPods[applicationName]
+				for _, pod := range pods {
+					if pod.Annotations["linkerd.io/inject"] == "disabled" {
+						continue
+					}
+				}
+
+				if !application.Namespace.Open {
+					for _, applicationNameFrom := range communication.From {
+						applicationFrom, _, _ := config.GetApplication(applicationNameFrom)
+						if applicationFrom != nil && !applicationFrom.Namespace.Open {
+							continue
+						}
+						openToClosedAccess[applicationNameFrom] = applicationName
+					}
+				}
+			}
+		}
+	}
+
+	for appFrom, appTo := range openToClosedAccess {
+		LogValidationMsg(Error, "Access from 'open' application '%s' to 'closed' application '%s'",
+			appFrom, appTo)
+	}
+
 	return nil
 }
 

example/config.yaml

@@ -27,6 +27,8 @@ namespaces:
           - port: 8081
           - port: 8082
             protocol: UDP
+        serviceAccounts:
+          - jantje
         matchLabels: 
           app: nexus-server
         #matchExpressions: