kola: add minMemory in kola.json (external tests)

mantle/kola/README-kola-ext.md

@@ -105,8 +105,9 @@ Here's an example `kola.json`:
 {
     "architectures": "!s390x ppc64le",
     "platforms": "qemu-unpriv",
-    "tags": "sometagname needs-internet othertag"
-    "additionalDisks": [ "5G" ]
+    "tags": "sometagname needs-internet othertag",
+    "additionalDisks": [ "5G" ],
+    "minMemory": 4096
 }
 ```
 
@@ -129,6 +130,11 @@ Currently only the `qemu` platform enforces this restriction.
 The `additionalDisks` key has the same semantics as the `--add-disk`
 argument to `qemuexec`. It is currently only supported on `qemu-unpriv`.
 
+The `minMemory` key takes a size in MB and ensures that an instance type
+with at least the specified amount of memory is used. On QEMU, this is
+equivalent to the `--memory` argument to `qemuexec`. This is currently
+only enforced on `qemu-unpriv`.
+
 More recently, you can also (useful for shell scripts) include the JSON file
 inline per test, like this:
 

mantle/kola/harness.go

@@ -534,6 +534,7 @@ type externalTestMeta struct {
 	Distros         string   `json:",distros,omitempty"`
 	Tags            string   `json:",tags,omitempty"`
 	AdditionalDisks []string `json:",additionalDisks,omitempty"`
+	MinMemory       int      `json:",minMemory,omitempty"`
 }
 
 // metadataFromTestBinary extracts JSON-in-comment like:
@@ -662,6 +663,7 @@ ExecStart=%s
 		Tags:          []string{"external"},
 
 		AdditionalDisks: targetMeta.AdditionalDisks,
+		MinMemory:       targetMeta.MinMemory,
 
 		Run: func(c cluster.TestCluster) {
 			mach := c.Machines()[0]
@@ -896,7 +898,11 @@ func runTest(h *harness.H, t *register.Test, pltfrm string, flight platform.Flig
 			userdata = t.UserDataV3
 		}
 
-		if _, err := platform.NewMachines(c, userdata, t.ClusterSize, t.AdditionalDisks); err != nil {
+		options := platform.MachineOptions{
+			AdditionalDisks: t.AdditionalDisks,
+			MinMemory:       t.MinMemory,
+		}
+		if _, err := platform.NewMachines(c, userdata, t.ClusterSize, options); err != nil {
 			h.Fatalf("Cluster failed starting machines: %v", err)
 		}
 	}

mantle/kola/register/register.go

@@ -69,6 +69,9 @@ type Test struct {
 	// "5G"]) -- defaults to none.
 	AdditionalDisks []string
 
+	// Minimum amount of memory required for test.
+	MinMemory int
+
 	// ExternalTest is a path to a binary that will be uploaded
 	ExternalTest string
 	// DependencyDir is a path to directory that will be uploaded, normally used by external tests

mantle/platform/machine/unprivqemu/cluster.go

@@ -112,6 +112,8 @@ func (qc *Cluster) NewMachineWithQemuOptions(userdata *conf.UserData, options pl
 			return nil, errors.Wrapf(err, "parsing memory option")
 		}
 		builder.Memory = int(memory)
+	} else if options.MinMemory != 0 {
+		builder.Memory = options.MinMemory
 	}
 
 	channel := "virtio"

mantle/platform/platform.go

@@ -156,6 +156,7 @@ type Flight interface {
 
 type MachineOptions struct {
 	AdditionalDisks []string
+	MinMemory       int
 }
 
 // SystemdDropin is a userdata type agnostic struct representing a systemd dropin
@@ -354,7 +355,7 @@ func CopyDirToMachine(inputdir string, m Machine, destdir string) error {
 
 // NewMachines spawns n instances in cluster c, with
 // each instance passed the same userdata.
-func NewMachines(c Cluster, userdata *conf.UserData, n int, addDisks []string) ([]Machine, error) {
+func NewMachines(c Cluster, userdata *conf.UserData, n int, options MachineOptions) ([]Machine, error) {
 	var wg sync.WaitGroup
 
 	mchan := make(chan Machine, n)
@@ -364,9 +365,6 @@ func NewMachines(c Cluster, userdata *conf.UserData, n int, addDisks []string) (
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			options := MachineOptions{
-				AdditionalDisks: addDisks,
-			}
 			m, err := c.NewMachineWithOptions(userdata, options)
 			if err != nil {
 				errchan <- err