feat: virtual nodes advertise ephemeral storage

pkg/virtualkubelet/config.go

@@ -102,6 +102,10 @@ type Resources struct {
 	Memory string `yaml:"Memory,omitempty"`
 	// Pods specifies the maximum number of pods this node can handle
 	Pods string `yaml:"Pods,omitempty"`
+	// EphemeralStorage is the ephemeral storage the node advertises (default 1Ti). A node
+	// that advertises none cannot take a pod that requests some, as sidecars often do
+	// (Katib's metrics collector requests 500Mi).
+	EphemeralStorage string `yaml:"EphemeralStorage,omitempty"`
 	// Accelerators lists hardware accelerators available on this node
 	Accelerators []Accelerator `yaml:"Accelerators"`
 }

pkg/virtualkubelet/config_test.go

@@ -2,10 +2,13 @@ package virtualkubelet
 
 import (
 	"context"
+	"os"
+	"path/filepath"
 	"testing"
 
 	types "github.com/interlink-hq/interlink/pkg/interlink"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
 )
@@ -464,3 +467,34 @@ func TestUpdateNodeTaints_NilLeavesExistingTaintsUnchangedAndUnknownEffectDefaul
 		},
 	}, provider.node.Spec.Taints)
 }
+
+// A virtual node must advertise ephemeral storage, or a pod whose sidecar requests some
+// (Katib's metrics collector: 500Mi) is never scheduled on it.
+func TestGetResources_EphemeralStorage(t *testing.T) {
+	config := Config{Resources: Resources{CPU: "10", Memory: "10Gi", Pods: "10"}}
+	got := GetResources(config)[v1.ResourceEphemeralStorage]
+	assert.Equal(t, defaultEphemeralStorage, got.String())
+
+	config.Resources.EphemeralStorage = "50Gi"
+	got = GetResources(config)[v1.ResourceEphemeralStorage]
+	assert.Equal(t, "50Gi", got.String())
+}
+
+func TestLoadConfig_EphemeralStorage(t *testing.T) {
+	load := func(resources string) (Config, error) {
+		path := filepath.Join(t.TempDir(), "config.yaml")
+		require.NoError(t, os.WriteFile(path, []byte("Resources:\n"+resources), 0o600))
+		return LoadConfig(t.Context(), path)
+	}
+
+	_, err := load("  EphemeralStorage: 50GB\n")
+	assert.ErrorContains(t, err, "invalid ephemeral storage value 50GB")
+
+	config, err := load("  EphemeralStorage: 50Gi\n")
+	require.NoError(t, err)
+	assert.Equal(t, "50Gi", config.Resources.EphemeralStorage)
+
+	config, err = load("  CPU: \"10\"\n")
+	require.NoError(t, err)
+	assert.Empty(t, config.Resources.EphemeralStorage)
+}

pkg/virtualkubelet/virtualkubelet.go

@@ -382,6 +382,10 @@ func NodeConditionWithInterlink(ready bool, interlinkStatus v1.ConditionStatus,
 	return append(conditions, interlinkCondition)
 }
 
+// defaultEphemeralStorage is advertised when Resources.EphemeralStorage is not set: the
+// remote side has its own disks, so the node only must not refuse pods that ask for some.
+const defaultEphemeralStorage = "1Ti"
+
 func GetResources(config Config) v1.ResourceList {
 	gpuCount := map[string]resource.Quantity{}
 	fpgaCount := map[string]resource.Quantity{}
@@ -401,10 +405,15 @@ func GetResources(config Config) v1.ResourceList {
 		}
 	}
 
+	ephemeralStorage := config.Resources.EphemeralStorage
+	if ephemeralStorage == "" {
+		ephemeralStorage = defaultEphemeralStorage
+	}
 	resourceList := v1.ResourceList{
-		"cpu":    resource.MustParse(config.Resources.CPU),
-		"memory": resource.MustParse(config.Resources.Memory),
-		"pods":   resource.MustParse(config.Resources.Pods),
+		"cpu":                       resource.MustParse(config.Resources.CPU),
+		"memory":                    resource.MustParse(config.Resources.Memory),
+		"pods":                      resource.MustParse(config.Resources.Pods),
+		v1.ResourceEphemeralStorage: resource.MustParse(ephemeralStorage),
 	}
 
 	for resourceType, q := range gpuCount {
@@ -650,6 +659,11 @@ func LoadConfig(ctx context.Context, providerConfig string) (config Config, err
 	if _, err = resource.ParseQuantity(config.Resources.Pods); err != nil {
 		return config, fmt.Errorf("invalid pods value %v", config.Resources.Pods)
 	}
+	if config.Resources.EphemeralStorage != "" {
+		if _, err = resource.ParseQuantity(config.Resources.EphemeralStorage); err != nil {
+			return config, fmt.Errorf("invalid ephemeral storage value %v", config.Resources.EphemeralStorage)
+		}
+	}
 	for _, accelerator := range config.Resources.Accelerators {
 		if _, err = resource.ParseQuantity(accelerator.Available); err != nil {
 			return config, fmt.Errorf("invalid value for accelerator %v (model: %v): %v", accelerator.ResourceType, accelerator.Model, err)