Allow byte values in limits.memory.swap

doc/api-extensions.md

@@ -2430,3 +2430,6 @@ Those integrations attach to network peers through some new fields:
 
 * `type` (`local` for current behavior, `remote` for integrations)
 * `target_integration` (reference to the integration)
+
+## `instance_memory_swap_bytes`
+This extends `limits.memory.swap` to allow for a total limit in bytes.

doc/config_options.txt

@@ -439,9 +439,11 @@ If this option is set to `false`, regular system memory is used.
 :condition: "container"
 :defaultdesc: "`true`"
 :liveupdate: "yes"
-:shortdesc: "Whether to encourage/discourage swapping less used pages for this instance"
-:type: "bool"
-
+:shortdesc: "Control swap usage by the instance"
+:type: "string"
+When set to `true` or `false`, it controls whether the container is likely to get some of
+its memory swapped by the kernel. Alternatively, it can be set to a bytes value which will
+then allow the container to make use of additional memory through swap.
 ```
 
 ```{config:option} limits.memory.swap.priority instance-resource-limits

internal/instance/config.go

@@ -506,14 +506,16 @@ var InstanceConfigKeysContainer = map[string]func(value string) error{
 	"limits.memory.enforce": validate.Optional(validate.IsOneOf("soft", "hard")),
 
 	// gendoc:generate(entity=instance, group=resource-limits, key=limits.memory.swap)
-	//
+	// When set to `true` or `false`, it controls whether the container is likely to get some of
+	// its memory swapped by the kernel. Alternatively, it can be set to a bytes value which will
+	// then allow the container to make use of additional memory through swap.
 	// ---
-	//  type: bool
+	//  type: string
 	//  defaultdesc: `true`
 	//  liveupdate: yes
 	//  condition: container
-	//  shortdesc: Whether to encourage/discourage swapping less used pages for this instance
-	"limits.memory.swap": validate.Optional(validate.IsBool),
+	//  shortdesc: Control swap usage by the instance
+	"limits.memory.swap": validate.Optional(validate.Or(validate.IsBool, validate.IsSize)),
 
 	// gendoc:generate(entity=instance, group=resource-limits, key=limits.memory.swap.priority)
 	// Specify an integer between 0 and 10.

internal/server/instance/drivers/driver_lxc.go

@@ -1155,27 +1155,28 @@ func (d *lxc) initLXC(config bool) (*liblxc.Container, error) {
 					return nil, err
 				}
 			} else {
-				if d.state.OS.CGInfo.Supports(cgroup.MemorySwap, cg) {
-					err = cg.SetMemoryLimit(valueInt)
-					if err != nil {
-						return nil, err
-					}
+				err = cg.SetMemoryLimit(valueInt)
+				if err != nil {
+					return nil, err
+				}
 
-					if util.IsFalse(memorySwap) {
+				if d.state.OS.CGInfo.Supports(cgroup.MemorySwap, cg) {
+					if util.IsTrueOrEmpty(memorySwap) || util.IsFalse(memorySwap) {
 						err = cg.SetMemorySwapLimit(0)
 						if err != nil {
 							return nil, err
 						}
 					} else {
-						err = cg.SetMemorySwapLimit(valueInt)
+						// Additional memory as swap.
+						swapInt, err := units.ParseByteSizeString(memorySwap)
+						if err != nil {
+							return nil, err
+						}
+
+						err = cg.SetMemorySwapLimit(swapInt)
 						if err != nil {
 							return nil, err
 						}
-					}
-				} else {
-					err = cg.SetMemoryLimit(valueInt)
-					if err != nil {
-						return nil, err
 					}
 				}
 
@@ -4624,31 +4625,32 @@ func (d *lxc) Update(args db.InstanceArgs, userRequested bool) error {
 						return err
 					}
 				} else {
-					if d.state.OS.CGInfo.Supports(cgroup.MemorySwap, cg) {
-						err = cg.SetMemoryLimit(memoryInt)
-						if err != nil {
-							revertMemory()
-							return err
-						}
+					err = cg.SetMemoryLimit(memoryInt)
+					if err != nil {
+						revertMemory()
+						return err
+					}
 
-						if util.IsFalse(memorySwap) {
+					if d.state.OS.CGInfo.Supports(cgroup.MemorySwap, cg) {
+						if util.IsTrueOrEmpty(memorySwap) || util.IsFalse(memorySwap) {
 							err = cg.SetMemorySwapLimit(0)
 							if err != nil {
 								revertMemory()
 								return err
 							}
 						} else {
-							err = cg.SetMemorySwapLimit(memoryInt)
+							// Additional memory as swap.
+							swapInt, err := units.ParseByteSizeString(memorySwap)
+							if err != nil {
+								revertMemory()
+								return err
+							}
+
+							err = cg.SetMemorySwapLimit(swapInt)
 							if err != nil {
 								revertMemory()
 								return err
 							}
-						}
-					} else {
-						err = cg.SetMemoryLimit(memoryInt)
-						if err != nil {
-							revertMemory()
-							return err
 						}
 					}
 
@@ -4666,7 +4668,6 @@ func (d *lxc) Update(args db.InstanceArgs, userRequested bool) error {
 
 				// Configure the swappiness
 				if key == "limits.memory.swap" || key == "limits.memory.swap.priority" {
-					memorySwap := d.expandedConfig["limits.memory.swap"]
 					memorySwapPriority := d.expandedConfig["limits.memory.swap.priority"]
 					if util.IsFalse(memorySwap) {
 						err = cg.SetMemorySwappiness(0)

internal/server/metadata/configuration.json

@@ -453,9 +453,9 @@
 							"condition": "container",
 							"defaultdesc": "`true`",
 							"liveupdate": "yes",
-							"longdesc": "",
-							"shortdesc": "Whether to encourage/discourage swapping less used pages for this instance",
-							"type": "bool"
+							"longdesc": "When set to `true` or `false`, it controls whether the container is likely to get some of\nits memory swapped by the kernel. Alternatively, it can be set to a bytes value which will\nthen allow the container to make use of additional memory through swap.",
+							"shortdesc": "Control swap usage by the instance",
+							"type": "string"
 						}
 					},
 					{

internal/server/project/permissions.go

@@ -836,6 +836,7 @@ func isContainerLowLevelOptionForbidden(key string) bool {
 		"boot.host_shutdown_action",
 		"boot.host_shutdown_timeout",
 		"linux.kernel_modules",
+		"limits.memory.swap",
 		"raw.apparmor",
 		"raw.idmap",
 		"raw.lxc",

internal/version/api.go

@@ -406,6 +406,7 @@ var APIExtensions = []string{
 	"numa_cpu_balanced",
 	"image_restriction_nesting",
 	"network_integrations",
+	"instance_memory_swap_bytes",
 }
 
 // APIExtensionsCount returns the number of available API extensions.