kvserver: add AdminSplit and AdminScatter to secondary tenants API

This adds support for AdminSplit and AdminScatter for secondary tenants.
This API allows indicating to KV that more data will be ingested, and
so the range should be split and re-distributed across the cluster.
This API will not be exposed through SQL, and in the future we might change
it to give KV more control over whether and how to deal with expected ingest
load. More discussion can be found in the github issue: #74389
 and Epic: https://cockroachlabs.atlassian.net/browse/CRDB-10720

Release note: None

pkg/rpc/auth_tenant.go

@@ -149,12 +149,14 @@ var reqMethodAllowlist = [...]bool{
 	roachpb.Scan:           true,
 	roachpb.ReverseScan:    true,
 	roachpb.EndTxn:         true,
+	roachpb.AdminSplit:     true,
 	roachpb.HeartbeatTxn:   true,
 	roachpb.QueryTxn:       true,
 	roachpb.QueryIntent:    true,
 	roachpb.InitPut:        true,
-	roachpb.AddSSTable:     true,
 	roachpb.Export:         true,
+	roachpb.AdminScatter:   true,
+	roachpb.AddSSTable:     true,
 	roachpb.Refresh:        true,
 	roachpb.RefreshRange:   true,
 }

pkg/rpc/auth_test.go

@@ -163,11 +163,21 @@ func TestTenantAuthRequest(t *testing.T) {
 		h := roachpb.RequestHeaderFromSpan(s)
 		return &roachpb.ScanRequest{RequestHeader: h}
 	}
-	makeAdminReq := func(key string) roachpb.Request {
+	makeDisallowedAdminReq := func(key string) roachpb.Request {
+		s := makeSpan(key)
+		h := roachpb.RequestHeader{Key: s.Key}
+		return &roachpb.AdminUnsplitRequest{RequestHeader: h}
+	}
+	makeAdminSplitReq := func(key string) roachpb.Request {
 		s := makeSpan(key)
 		h := roachpb.RequestHeaderFromSpan(s)
 		return &roachpb.AdminSplitRequest{RequestHeader: h, SplitKey: s.Key}
 	}
+	makeAdminScatterReq := func(key string) roachpb.Request {
+		s := makeSpan(key)
+		h := roachpb.RequestHeaderFromSpan(s)
+		return &roachpb.AdminScatterRequest{RequestHeader: h}
+	}
 	makeReqs := func(reqs ...roachpb.Request) []roachpb.RequestUnion {
 		ru := make([]roachpb.RequestUnion, len(reqs))
 		for i, r := range reqs {
@@ -249,35 +259,99 @@ func TestTenantAuthRequest(t *testing.T) {
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(
-					makeAdminReq("a"),
+					makeDisallowedAdminReq("a"),
+				)},
+				expErr: `request \[1 AdmUnsplit\] not permitted`,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeDisallowedAdminReq(prefix(10, "a")),
 				)},
-				expErr: `request \[1 AdmSplit\] not permitted`,
+				expErr: `request \[1 AdmUnsplit\] not permitted`,
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(
-					makeAdminReq(prefix(10, "a")),
+					makeDisallowedAdminReq(prefix(50, "a")),
 				)},
-				expErr: `request \[1 AdmSplit\] not permitted`,
+				expErr: `request \[1 AdmUnsplit\] not permitted`,
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(
-					makeAdminReq(prefix(50, "a")),
+					makeDisallowedAdminReq(prefix(10, "a")),
+					makeReq(prefix(10, "a"), prefix(10, "b")),
 				)},
-				expErr: `request \[1 AdmSplit\] not permitted`,
+				expErr: `request \[1 Scan, 1 AdmUnsplit\] not permitted`,
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(
-					makeAdminReq(prefix(10, "a")),
 					makeReq(prefix(10, "a"), prefix(10, "b")),
+					makeDisallowedAdminReq(prefix(10, "a")),
+				)},
+				expErr: `request \[1 Scan, 1 AdmUnsplit\] not permitted`,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminSplitReq("a"),
 				)},
-				expErr: `request \[1 Scan, 1 AdmSplit\] not permitted`,
+				expErr: `requested key span a{-\\x00} not fully contained in tenant keyspace /Tenant/1{0-1}`,
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminSplitReq(prefix(10, "a")),
+				)},
+				expErr: noError,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminSplitReq(prefix(50, "a")),
+				)},
+				expErr: `requested key span /Tenant/50"a{"-\\x00"} not fully contained in tenant keyspace /Tenant/1{0-1}`,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminSplitReq(prefix(10, "a")),
 					makeReq(prefix(10, "a"), prefix(10, "b")),
-					makeAdminReq(prefix(10, "a")),
 				)},
-				expErr: `request \[1 Scan, 1 AdmSplit\] not permitted`,
+				expErr: noError,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeReq(prefix(10, "a"), prefix(10, "b")),
+					makeAdminSplitReq(prefix(10, "a")),
+				)},
+				expErr: noError,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminScatterReq("a"),
+				)},
+				expErr: `requested key span a{-\\x00} not fully contained in tenant keyspace /Tenant/1{0-1}`,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminScatterReq(prefix(10, "a")),
+				)},
+				expErr: noError,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminScatterReq(prefix(50, "a")),
+				)},
+				expErr: `requested key span /Tenant/50"a{"-\\x00"} not fully contained in tenant keyspace /Tenant/1{0-1}`,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeAdminScatterReq(prefix(10, "a")),
+					makeReq(prefix(10, "a"), prefix(10, "b")),
+				)},
+				expErr: noError,
+			},
+			{
+				req: &roachpb.BatchRequest{Requests: makeReqs(
+					makeReq(prefix(10, "a"), prefix(10, "b")),
+					makeAdminScatterReq(prefix(10, "a")),
+				)},
+				expErr: noError,
 			},
 			{
 				req: &roachpb.BatchRequest{Requests: makeReqs(