roachtest: metamorphically enable leader leases

Part of #132762.

To increase test coverage of leader leases, this patch adds leader leases
to the set of possible lease types when tests opt-in to metamorphic leases.
As of fc68b0f, most roachtests do enable metamorphic leases, so this will
provide good coverage of leader leases.

Release note: None

pkg/cmd/roachtest/registry/test_spec.go

@@ -244,10 +244,14 @@ const (
 	LeaderLeases
 	// MetamorphicLeases randomly chooses epoch or expiration
 	// leases (across the entire cluster).
-	// TODO(nvanbenschoten): add leader leases to this mix.
 	MetamorphicLeases
 )
 
+// LeaseTypes contains all lease types.
+//
+// The list does not contain aliases like "default" and "metamorphic".
+var LeaseTypes = []LeaseType{EpochLeases, ExpirationLeases, LeaderLeases}
+
 // CloudSet represents a set of clouds.
 //
 // Instances of CloudSet are immutable. The uninitialized (zero) value is not

pkg/cmd/roachtest/test_runner.go

@@ -898,7 +898,18 @@ func (r *testRunner) runWorker(
 				c.clusterSettings = map[string]string{}
 				c.virtualClusterSettings = map[string]string{}
 
-				switch testSpec.Leases {
+				leases := testSpec.Leases
+				if leases == registry.MetamorphicLeases {
+					// 50% change of using the default lease type, 50% change of choosing
+					// a random, specific lease type.
+					if prng.Intn(2) == 0 {
+						leases = registry.DefaultLeases
+					} else {
+						leases = registry.LeaseTypes[prng.Intn(len(registry.LeaseTypes))]
+					}
+					c.status(fmt.Sprintf("metamorphically using %s leases", leases))
+				}
+				switch leases {
 				case registry.DefaultLeases:
 				case registry.EpochLeases:
 					c.clusterSettings["kv.expiration_leases_only.enabled"] = "false"
@@ -909,12 +920,9 @@ func (r *testRunner) runWorker(
 					c.clusterSettings["kv.expiration_leases_only.enabled"] = "false"
 					c.clusterSettings["kv.raft.leader_fortification.fraction_enabled"] = "1.0"
 				case registry.MetamorphicLeases:
-					enabled := prng.Float64() < 0.5
-					c.status(fmt.Sprintf("metamorphically setting kv.expiration_leases_only.enabled = %t",
-						enabled))
-					c.clusterSettings["kv.expiration_leases_only.enabled"] = fmt.Sprintf("%t", enabled)
+					t.Fatalf("metamorphic leases handled above")
 				default:
-					t.Fatalf("unknown lease type %s", testSpec.Leases)
+					t.Fatalf("unknown lease type %s", leases)
 				}
 
 				c.goCoverDir = t.GoCoverArtifactsDir()

pkg/cmd/roachtest/tests/failover.go

@@ -59,8 +59,7 @@ var rangeLeaseRenewalDuration = func() time.Duration {
 // requests are successful with nominal latencies. See also:
 // https://github.com/cockroachdb/cockroach/issues/103654
 func registerFailover(r registry.Registry) {
-	leaseTypes := []registry.LeaseType{registry.EpochLeases, registry.ExpirationLeases, registry.LeaderLeases}
-	for _, leases := range leaseTypes {
+	for _, leases := range registry.LeaseTypes {
 		var leasesStr string
 		switch leases {
 		case registry.EpochLeases: