Allow overriding lease name for a reconciler (#2435)

Add a `map-lease-prefix` prefix for config keys for
`config-leader-election` that is a map from a generated lease prefix
to a new prefix:

```yaml
map-lease-prefix.<component>.<package>.<reconciler_type_name>: <new_prefix>
map-lease-prefix.<component-x>.<package-x>.<reconciler_type_name-x>: <new_prefix>
```

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

configmap/parse.go

@@ -244,3 +244,16 @@ func Parse(data map[string]string, parsers ...ParseFunc) error {
 	}
 	return nil
 }
+
+// AsOptionalMap parses the data into the target as a map[string]string, if it exists.
+// The map is represented as a list of key-value pairs with a common prefix.
+func AsOptionalMap(prefix string, target map[string]string) ParseFunc {
+	return func(data map[string]string) error {
+		for k, v := range data {
+			if strings.HasPrefix(k, prefix) && len(k) > len(prefix)+1 {
+				target[k[len(prefix)+1: /* remove dot `.` */]] = v
+			}
+		}
+		return nil
+	}
+}

configmap/parse_test.go

@@ -42,6 +42,8 @@ type testConfig struct {
 
 	nsn  types.NamespacedName
 	onsn *types.NamespacedName
+
+	dict map[string]string
 }
 
 func TestParse(t *testing.T) {
@@ -70,6 +72,12 @@ func TestParse(t *testing.T) {
 
 			"test-namespaced-name":          "some-namespace/some-name",
 			"test-optional-namespaced-name": "some-other-namespace/some-other-name",
+
+			"test-dict.k":  "v",
+			"test-dict.k1": "v1",
+		},
+		conf: testConfig{
+			dict: map[string]string{},
 		},
 		want: testConfig{
 			str:    "foo.bar",
@@ -92,6 +100,10 @@ func TestParse(t *testing.T) {
 				Name:      "some-other-name",
 				Namespace: "some-other-namespace",
 			},
+			dict: map[string]string{
+				"k":  "v",
+				"k1": "v1",
+			},
 		},
 	}, {
 		name: "respect defaults",
@@ -175,6 +187,18 @@ func TestParse(t *testing.T) {
 			"test-namespaced-name": "default/resource/whut",
 		},
 		expectErr: true,
+	}, {
+		name: "dict without key and dot",
+		data: map[string]string{
+			"test-dict": "v",
+		},
+		expectErr: false,
+	}, {
+		name: "dict without key",
+		data: map[string]string{
+			"test-dict.": "v",
+		},
+		expectErr: false,
 	}}
 
 	for _, test := range tests {
@@ -194,6 +218,7 @@ func TestParse(t *testing.T) {
 				AsQuantity("test-quantity", &test.conf.qua),
 				AsNamespacedName("test-namespaced-name", &test.conf.nsn),
 				AsOptionalNamespacedName("test-optional-namespaced-name", &test.conf.onsn),
+				AsOptionalMap("test-dict", test.conf.dict),
 			); (err == nil) == test.expectErr {
 				t.Fatal("Failed to parse data:", err)
 			}

leaderelection/config.go

@@ -56,6 +56,8 @@ func NewConfigFromMap(data map[string]string) (*Config, error) {
 		cm.AsDuration("retry-period", &config.RetryPeriod),
 
 		cm.AsUint32("buckets", &config.Buckets),
+
+		cm.AsOptionalMap("map-lease-prefix", config.LeaseNamesPrefixMapping),
 	); err != nil {
 		return nil, err
 	}
@@ -79,19 +81,21 @@ func NewConfigFromConfigMap(configMap *corev1.ConfigMap) (*Config, error) {
 // contained within a single namespace. Typically these will correspond to a
 // single source repository, viz: serving or eventing.
 type Config struct {
-	Buckets       uint32
-	LeaseDuration time.Duration
-	RenewDeadline time.Duration
-	RetryPeriod   time.Duration
+	Buckets                 uint32
+	LeaseDuration           time.Duration
+	RenewDeadline           time.Duration
+	RetryPeriod             time.Duration
+	LeaseNamesPrefixMapping map[string]string
 }
 
 func (c *Config) GetComponentConfig(name string) ComponentConfig {
 	return ComponentConfig{
-		Component:     name,
-		Buckets:       c.Buckets,
-		LeaseDuration: c.LeaseDuration,
-		RenewDeadline: c.RenewDeadline,
-		RetryPeriod:   c.RetryPeriod,
+		Component:               name,
+		Buckets:                 c.Buckets,
+		LeaseDuration:           c.LeaseDuration,
+		RenewDeadline:           c.RenewDeadline,
+		RetryPeriod:             c.RetryPeriod,
+		LeaseNamesPrefixMapping: c.LeaseNamesPrefixMapping,
 	}
 }
 
@@ -123,6 +127,11 @@ type ComponentConfig struct {
 	// be generated to be used as identity for each BuildElector call.
 	// Autoscaler uses the pod IP as identity.
 	Identity string
+
+	// LeaseNamesPrefixMapping maps lease prefixes
+	// from <component>.<package>.<reconciler_type_name> to the
+	// associated value when using standardBuilder.
+	LeaseNamesPrefixMapping map[string]string
 }
 
 // statefulSetID is a envconfig Decodable controller ordinal and name.

leaderelection/context.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/leaderelection"
 	"k8s.io/client-go/tools/leaderelection/resourcelock"
+
 	"knative.dev/pkg/hash"
 	"knative.dev/pkg/logging"
 	"knative.dev/pkg/network"
@@ -192,7 +193,11 @@ func newStandardBuckets(queueName string, cc ComponentConfig) []reconciler.Bucke
 }
 
 func standardBucketName(ordinal uint32, queueName string, cc ComponentConfig) string {
-	return strings.ToLower(fmt.Sprintf("%s.%s.%02d-of-%02d", cc.Component, queueName, ordinal, cc.Buckets))
+	prefix := fmt.Sprintf("%s.%s", cc.Component, queueName)
+	if v, ok := cc.LeaseNamesPrefixMapping[prefix]; ok && len(v) > 0 {
+		prefix = v
+	}
+	return strings.ToLower(fmt.Sprintf("%s.%02d-of-%02d", prefix, ordinal, cc.Buckets))
 }
 
 type statefulSetBuilder struct {

leaderelection/context_test.go

@@ -29,6 +29,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	fakekube "k8s.io/client-go/kubernetes/fake"
 	ktesting "k8s.io/client-go/testing"
+
 	"knative.dev/pkg/reconciler"
 	_ "knative.dev/pkg/system/testing"
 )
@@ -355,3 +356,42 @@ func TestWithUnopposedElector(t *testing.T) {
 	// Wait to see if PromoteFunc is called with nil or our enq function.
 	<-time.After(time.Second)
 }
+
+func TestStandardBucketName(t *testing.T) {
+	tests := []struct {
+		name      string
+		ordinal   uint32
+		queueName string
+		cc        ComponentConfig
+		want      string
+	}{
+		{
+			name:      "identity",
+			ordinal:   0,
+			queueName: "queue-queue",
+			cc: ComponentConfig{
+				Component: "my-comp",
+			},
+			want: "my-comp.queue-queue.00-of-00",
+		},
+		{
+			name:      "remapping",
+			ordinal:   0,
+			queueName: "queue-queue",
+			cc: ComponentConfig{
+				Component: "my-comp",
+				LeaseNamesPrefixMapping: map[string]string{
+					"my-comp.queue-queue": "my-comp-2.queue",
+				},
+			},
+			want: "my-comp-2.queue.00-of-00",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := standardBucketName(tt.ordinal, tt.queueName, tt.cc); got != tt.want {
+				t.Errorf("got %v, want %v", got, tt.want)
+			}
+		})
+	}
+}