feat: implement configurable behavior for the nswatcher

README.md

@@ -36,8 +36,10 @@ Basically, it spawns a new [goroutine](https://go.dev/tour/concurrency/1) with a
 [CRD Watcher](#crd-watcher) every time a new namespace is detected and it stops the
 corresponding goroutine when a namespace is deleted.
 
-In the future, there will be the possibility to blacklist (or whitelist) some namespaces
-depending on an annotation.
+The Namespace can be [configured](#configuration) to either monitor all namespaces by
+default (with an opt-out strategy) or to monitor only the namespaces which contain the
+label `cm.massix.github.io/namespace="true"`. Check the [Configuration](#configuration)
+paragraph for more details.
 
 ### CRD Watcher
 We make use of a
@@ -178,13 +180,32 @@ spec:
 ```
 
 ## Configuration
-The only configuration possible for the ChaosMonkey is setting the minimum log level,
-this is done by setting the environment variable `CHAOSMONKEY_LOGLEVEL` to one of the
-following values: `trace`, `debug`, `info`, `warn`, `error`, `critical` or `panic`.
-
-The value is not case-sensitive.
-
-Invalid or empty values will make ChaosMonkey default to the `info` level.
+There are two configurable parts of the ChaosMonkey (on top of what the [CRD](./crds/chaosmonkey-configuration.yaml)
+already permits of course).
+
+**Minimum Log Level**: this is configurable using the environment variable `CHAOSMONKEY_LOGLEVEL`,
+it accepts the following self explaining values: `trace`, `debug`, `info`, `warn`, `error`,
+`critical` or `panic` and it sets the minimum log level for all the logging of the ChaosMonkey.
+
+The value is not case-sensitive, invalid or empty values will make ChaosMonkey default to
+the `info` level.
+
+**Default Behavior**: this is used to configure the way the [Namespace Watcher](#namespace-watcher) should
+behave in regards of additions and modifications of namespaces and it uses the environment
+variable `CHAOSMONKEY_BEHAVIOR`. It currently accepts two values: `AllowAll` or `DenyAll`
+(not case sensitive).
+
+Setting it to `AllowAll` means that by default all namespaces are monitored, if
+you want to opt-out a namespace you **must** create a new label in the
+metadata of the namespace: `cm.massix.github.io/namespace="false"`, this will
+make the Watcher ignore that namespace. All values which are not the string
+`false` will cause the Watcher to take that namespace into account.
+
+Setting it to `DenyAll` means that by default all namespaces are ignored, if
+you want to opt-in a namespace you **must** create a new label in
+the metadata of the namespace: `cm.massix.github.io/namespace="true"`, this will
+make the Watcher take that namespace into account. All values which are not
+the string `true` will cause the Watcher to ignore that namespace.
 
 ## Observability
 The Chaos Monkey exposes some metrics using the [Prometheus](https://prometheus.io/) library and format.

cmd/chaosmonkey/main.go

@@ -23,7 +23,7 @@ func main() {
 	log := logrus.WithFields(logrus.Fields{"component": "main"})
 
 	// Get the LogLevel from the environment variable
-	ll, err := configuration.FromEnvironment()
+	ll, err := configuration.LogrusLevelFromEnvironment()
 	if err != nil {
 		log.Warnf("No loglevel provided, using default: %s", logrus.GetLevel())
 	} else {
@@ -48,10 +48,19 @@ func main() {
 		panic(err)
 	}
 
+	log.Info("Configuring default behavior via environment variable")
+	behavior, err := configuration.BehaviorFromEnvironment()
+	if err != nil {
+		log.Warnf("Error while configuring default behavior: %s", err)
+
+		behavior = configuration.AllowAll
+		log.Warnf("Using default behavior: %s", behavior)
+	}
+
 	clientset := kubernetes.NewForConfigOrDie(cfg)
 	cmcClientset := versioned.NewForConfigOrDie(cfg)
 
-	nsWatcher := watcher.DefaultNamespaceFactory(clientset, cmcClientset, nil, namespace)
+	nsWatcher := watcher.DefaultNamespaceFactory(clientset, cmcClientset, nil, namespace, behavior)
 
 	// Hook signals
 	s := make(chan os.Signal, 1)

internal/configuration/behavior.go

@@ -0,0 +1,21 @@
+package configuration
+
+import (
+	"errors"
+	"os"
+	"strings"
+)
+
+func BehaviorFromEnvironment() (Behavior, error) {
+	if val, ok := os.LookupEnv("CHAOSMONKEY_BEHAVIOR"); ok {
+		val = strings.ToUpper(val)
+
+		if val == string(AllowAll) || val == string(DenyAll) {
+			return Behavior(val), nil
+		} else {
+			return "", &InvalidBehavior{providedBehaviour: val}
+		}
+	}
+
+	return "", errors.New("No environment variable provided")
+}

internal/configuration/behavior_test.go

@@ -0,0 +1,58 @@
+package configuration_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/massix/chaos-monkey/internal/configuration"
+)
+
+func TestBehavior_ParseFromEnvironment(t *testing.T) {
+	goodEnvValues := map[string]configuration.Behavior{
+		"allowall": configuration.AllowAll,
+		"ALLOWALL": configuration.AllowAll,
+		"AllOwAll": configuration.AllowAll,
+		"denyall":  configuration.DenyAll,
+		"DenyAll":  configuration.DenyAll,
+		"DENYALL":  configuration.DenyAll,
+	}
+
+	for key, val := range goodEnvValues {
+		t.Run(fmt.Sprintf("Can parse from environment (%s)", key), func(t *testing.T) {
+			t.Setenv("CHAOSMONKEY_BEHAVIOR", key)
+
+			if b, err := configuration.BehaviorFromEnvironment(); err != nil {
+				t.Error(err)
+			} else if b != val {
+				t.Errorf("Was expecting %s, got %s instead", val, b)
+			}
+		})
+	}
+
+	badEnvValues := []string{
+		"",
+		"invalid",
+		"geckos",
+	}
+
+	for _, val := range badEnvValues {
+		t.Run(fmt.Sprintf("It fails for invalid strings (%s)", val), func(t *testing.T) {
+			t.Setenv("CHAOSMONKEY_BEHAVIOR", val)
+
+			if b, err := configuration.BehaviorFromEnvironment(); err == nil {
+				t.Errorf("Was expecting error, received %s instead", b)
+			} else if err.Error() != fmt.Sprintf("Invalid behaviour: %s", strings.ToUpper(val)) {
+				t.Error(err)
+			}
+		})
+	}
+
+	t.Run("It fails if there is no environment variable", func(t *testing.T) {
+		if b, err := configuration.BehaviorFromEnvironment(); err == nil {
+			t.Errorf("Was expecting error, received %s instead", b)
+		} else if err.Error() != "No environment variable provided" {
+			t.Error(err)
+		}
+	})
+}

internal/configuration/logruslevel.go

@@ -0,0 +1,61 @@
+package configuration
+
+import (
+	"errors"
+	"os"
+	"slices"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+)
+
+func LogrusLevelFromEnvironment() (LogrusLevel, error) {
+	if val, ok := os.LookupEnv("CHAOSMONKEY_LOGLEVEL"); ok {
+		if newLevel, err := NewLogrusLevel(strings.ToLower(val)); err == nil {
+			return newLevel, nil
+		} else {
+			return "", err
+		}
+	}
+
+	return "", errors.New("No environment variable for configuring the log level found.")
+}
+
+func NewLogrusLevel(level string) (LogrusLevel, error) {
+	validLevels := []string{
+		"panic",
+		"fatal",
+		"error",
+		"warn",
+		"info",
+		"debug",
+		"trace",
+	}
+
+	if slices.Contains(validLevels, level) {
+		return LogrusLevel(level), nil
+	}
+
+	return "", &InvalidLogrusLevel{level}
+}
+
+func (l LogrusLevel) LogrusLevel() logrus.Level {
+	switch l {
+	case "panic":
+		return logrus.PanicLevel
+	case "fatal":
+		return logrus.FatalLevel
+	case "error":
+		return logrus.ErrorLevel
+	case "warn":
+		return logrus.WarnLevel
+	case "info":
+		return logrus.InfoLevel
+	case "debug":
+		return logrus.DebugLevel
+	case "trace":
+		return logrus.TraceLevel
+	default:
+		return logrus.InfoLevel
+	}
+}

internal/configuration/types_test.go → internal/configuration/logruslevel_test.go

@@ -1,7 +1,6 @@
 package configuration_test
 
 import (
-	"encoding/json"
 	"fmt"
 	"strings"
 	"testing"
@@ -10,10 +9,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-type UnmarshalTest struct {
-	Level configuration.LogrusLevel `json:"level"`
-}
-
 func Test_LogrusLevel(t *testing.T) {
 	t.Run("Can create a logrus level", func(t *testing.T) {
 		t.Parallel()
@@ -40,43 +35,14 @@ func Test_LogrusLevel(t *testing.T) {
 			t.Fatal(err)
 		}
 	})
-
-	t.Run("Can unmarshal a logrus level", func(t *testing.T) {
-		t.Parallel()
-
-		var unmarshalTest UnmarshalTest
-		err := json.Unmarshal([]byte(`{ "level": "trace" }`), &unmarshalTest)
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		if unmarshalTest.Level.LogrusLevel() != logrus.TraceLevel {
-			t.Fatal(unmarshalTest.Level.LogrusLevel())
-		}
-	})
-
-	t.Run("Will fail if level is not valid", func(t *testing.T) {
-		t.Parallel()
-
-		var unmarshalTest UnmarshalTest
-		err := json.Unmarshal([]byte(`{ "level": "invalid" }`), &unmarshalTest)
-		if err == nil {
-			t.Fatal("Was expecting error")
-		}
-
-		if err.Error() != "Invalid logrus level: invalid" {
-			t.Fatal(err)
-		}
-	})
 }
 
 func TestLogLevel_FromEnvironment(t *testing.T) {
 	for _, level := range []string{"PANIC", "FaTaL", "eRROR", "WARN", "info", "debug", "trace"} {
-		t.Logf("Testing with loglevel: %s", level)
 		t.Run(fmt.Sprintf("Can set loglevel from environment (%s)", level), func(t *testing.T) {
 			t.Setenv("CHAOSMONKEY_LOGLEVEL", level)
 
-			ll, err := configuration.FromEnvironment()
+			ll, err := configuration.LogrusLevelFromEnvironment()
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -88,11 +54,10 @@ func TestLogLevel_FromEnvironment(t *testing.T) {
 	}
 
 	for _, level := range []string{"", "invalid", "geckos"} {
-		t.Logf("Testing with loglevel: %s", level)
 		t.Run(fmt.Sprintf("It fails for invalid strings (%s)", level), func(t *testing.T) {
 			t.Setenv("CHAOSMONKEY_LOGLEVEL", level)
 
-			ll, err := configuration.FromEnvironment()
+			ll, err := configuration.LogrusLevelFromEnvironment()
 			if err == nil || ll != "" {
 				t.Fatalf("Was not expecting to succeed: %s", ll)
 			}
@@ -107,7 +72,7 @@ func TestLogLevel_FromEnvironment(t *testing.T) {
 	}
 
 	t.Run("It fails if there is no environment variable", func(t *testing.T) {
-		ll, err := configuration.FromEnvironment()
+		ll, err := configuration.LogrusLevelFromEnvironment()
 		if err == nil || ll != "" {
 			t.Fatal("Was not expecting to succeed")
 		}