play kube: set defaults to container resources

this fixes https://github.com/containers/podman/issues/13115

the change tries to immitate k8s behavior.
when limits are not set the container's limits are all CPU and all RAM
when requests are missing then they are equal to limits

Signed-off-by: Yaron Dayagi <ydayagi@redhat.com>

pkg/specgen/generate/kube/kube.go

@@ -7,6 +7,7 @@ import (
 	"math"
 	"net"
 	"regexp"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -22,6 +23,7 @@ import (
 	"github.com/containers/podman/v4/pkg/specgen"
 	"github.com/containers/podman/v4/pkg/specgen/generate"
 	"github.com/containers/podman/v4/pkg/util"
+	"github.com/docker/docker/pkg/system"
 	"github.com/docker/go-units"
 	spec "github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/pkg/errors"
@@ -700,8 +702,12 @@ func envVarValueResourceFieldRef(env v1.EnvVar, opts *CtrSpecGenOptions) (*strin
 		divisor.Set(1)
 	}
 
+	resources, err := getContainerResources(opts.Container)
+	if err != nil {
+		return nil, err
+	}
+
 	var value *resource.Quantity
-	resources := opts.Container.Resources
 	resourceName := env.ValueFrom.ResourceFieldRef.Resource
 	var isValidDivisor bool
 
@@ -757,6 +763,46 @@ func isCPUDivisor(divisor resource.Quantity) bool {
 	}
 }
 
+func getContainerResources(container v1.Container) (v1.ResourceRequirements, error) {
+	result := v1.ResourceRequirements{
+		Limits:   v1.ResourceList{},
+		Requests: v1.ResourceList{},
+	}
+
+	limits := container.Resources.Limits
+	requests := container.Resources.Requests
+
+	if limits == nil || limits.Memory().IsZero() {
+		mi, err := system.ReadMemInfo()
+		if err != nil {
+			return result, err
+		}
+		result.Limits[v1.ResourceMemory] = *resource.NewQuantity(mi.MemTotal, resource.DecimalSI)
+	} else {
+		result.Limits[v1.ResourceMemory] = limits[v1.ResourceMemory]
+	}
+
+	if limits == nil || limits.Cpu().IsZero() {
+		result.Limits[v1.ResourceCPU] = *resource.NewQuantity(int64(runtime.NumCPU()), resource.DecimalSI)
+	} else {
+		result.Limits[v1.ResourceCPU] = limits[v1.ResourceCPU]
+	}
+
+	if requests == nil || requests.Memory().IsZero() {
+		result.Requests[v1.ResourceMemory] = result.Limits[v1.ResourceMemory]
+	} else {
+		result.Requests[v1.ResourceMemory] = requests[v1.ResourceMemory]
+	}
+
+	if requests == nil || requests.Cpu().IsZero() {
+		result.Requests[v1.ResourceCPU] = result.Limits[v1.ResourceCPU]
+	} else {
+		result.Requests[v1.ResourceCPU] = requests[v1.ResourceCPU]
+	}
+
+	return result, nil
+}
+
 // getPodPorts converts a slice of kube container descriptions to an
 // array of portmapping
 func getPodPorts(containers []v1.Container) []types.PortMapping {

pkg/specgen/generate/kube/play_test.go

@@ -6,10 +6,12 @@ import (
 	"io/ioutil"
 	"math"
 	"os"
+	"runtime"
 	"strconv"
 	"testing"
 
 	"github.com/containers/common/pkg/secrets"
+	"github.com/docker/docker/pkg/system"
 	"github.com/stretchr/testify/assert"
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -193,6 +195,11 @@ func TestEnvVarValue(t *testing.T) {
 	assert.NoError(t, err)
 	defer os.RemoveAll(d)
 	secretsManager := createSecrets(t, d)
+	stringNumCPUs := strconv.Itoa(runtime.NumCPU())
+
+	mi, err := system.ReadMemInfo()
+	assert.Nil(t, err)
+	stringMemTotal := strconv.FormatInt(mi.MemTotal, 10)
 
 	tests := []struct {
 		name     string
@@ -694,6 +701,78 @@ func TestEnvVarValue(t *testing.T) {
 			true,
 			strconv.Itoa(int(float64(cpuInt) / 0.001)),
 		},
+		{
+			"ResourceFieldRefNoLimitMemory",
+			v1.EnvVar{
+				Name: "FOO",
+				ValueFrom: &v1.EnvVarSource{
+					ResourceFieldRef: &v1.ResourceFieldSelector{
+						Resource: "limits.memory",
+					},
+				},
+			},
+			CtrSpecGenOptions{
+				Container: v1.Container{
+					Name: "test",
+				},
+			},
+			true,
+			stringMemTotal,
+		},
+		{
+			"ResourceFieldRefNoRequestMemory",
+			v1.EnvVar{
+				Name: "FOO",
+				ValueFrom: &v1.EnvVarSource{
+					ResourceFieldRef: &v1.ResourceFieldSelector{
+						Resource: "requests.memory",
+					},
+				},
+			},
+			CtrSpecGenOptions{
+				Container: v1.Container{
+					Name: "test",
+				},
+			},
+			true,
+			stringMemTotal,
+		},
+		{
+			"ResourceFieldRefNoLimitCPU",
+			v1.EnvVar{
+				Name: "FOO",
+				ValueFrom: &v1.EnvVarSource{
+					ResourceFieldRef: &v1.ResourceFieldSelector{
+						Resource: "limits.cpu",
+					},
+				},
+			},
+			CtrSpecGenOptions{
+				Container: v1.Container{
+					Name: "test",
+				},
+			},
+			true,
+			stringNumCPUs,
+		},
+		{
+			"ResourceFieldRefNoRequestCPU",
+			v1.EnvVar{
+				Name: "FOO",
+				ValueFrom: &v1.EnvVarSource{
+					ResourceFieldRef: &v1.ResourceFieldSelector{
+						Resource: "requests.cpu",
+					},
+				},
+			},
+			CtrSpecGenOptions{
+				Container: v1.Container{
+					Name: "test",
+				},
+			},
+			true,
+			stringNumCPUs,
+		},
 	}
 
 	for _, test := range tests {