Implement resource constraints on nodes

go.sum

@@ -28,13 +28,15 @@ github.com/go-openapi/jsonpointer v0.0.0-20160704185906-46af16f9f7b1/go.mod h1:+
 github.com/go-openapi/jsonreference v0.0.0-20160704190145-13c6e3589ad9/go.mod h1:W3Z9FmVs9qj+KR4zFKmDPGiLdk1D9Rlm7cyMvf57TTg=
 github.com/go-openapi/spec v0.0.0-20160808142527-6aced65f8501/go.mod h1:J8+jY1nAiCcj+friV/PDoE1/3eeccG9LYBs0tYvLOWc=
 github.com/go-openapi/swag v0.0.0-20160704191624-1d0bd113de87/go.mod h1:DXUve3Dpr1UfpPtxFw+EFuQ41HhCWZfha5jSVRG7C7I=
+github.com/gogo/protobuf v1.2.2-0.20190723190241-65acae22fc9d h1:3PaI8p3seN09VjbTYC/QWlUZdZ1qS1zGjy7LH2Wt07I=
 github.com/gogo/protobuf v1.2.2-0.20190723190241-65acae22fc9d/go.mod h1:SlYgWuQ5SjCEi6WLHjHCa1yvBfUnHcTbrrZtXPKa29o=
 github.com/golang/groupcache v0.0.0-20160516000752-02826c3e7903/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/protobuf v0.0.0-20161109072736-4bd1920723d7/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/gofuzz v0.0.0-20161122191042-44d81051d367/go.mod h1:HP5RmnzzSNb993RKQDq4+1A4ia9nllfqcQFTQJedwGI=
+github.com/google/gofuzz v1.0.0 h1:A8PeW59pxE9IoFRqBp37U+mSNaQoZ46F1f0f863XSXw=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/uuid v1.1.1 h1:Gkbcsh/GbpXz7lPftLA3P6TYMwjCLYm83jiFQZF/3gY=
 github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
@@ -112,6 +114,7 @@ golang.org/x/sys v0.0.0-20200116001909-b77594299b42 h1:vEOn+mP2zCOVzKckCZy6YsCtD
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.0.0-20160726164857-2910a502d2bf/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20181011042414-1f849cf54d09/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
@@ -120,6 +123,7 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
+gopkg.in/inf.v0 v0.9.1 h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=
 gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

pkg/apis/config/v1alpha4/types.go

@@ -16,6 +16,10 @@ limitations under the License.
 
 package v1alpha4
 
+import (
+	"k8s.io/apimachinery/pkg/api/resource"
+)
+
 // Cluster contains kind cluster configuration
 type Cluster struct {
 	TypeMeta `yaml:",inline"`
@@ -106,6 +110,9 @@ type Node struct {
 	// binded to a host Port
 	ExtraPortMappings []PortMapping `yaml:"extraPortMappings,omitempty"`
 
+	// Constraints describes the node resources constraints
+	Constraints NodeResources `json:"constraints,omitempty"`
+
 	// KubeadmConfigPatches are applied to the generated kubeadm config as
 	// merge patches. The `kind` field must match the target object, and
 	// if `apiVersion` is specified it will only be applied to matching objects.
@@ -271,3 +278,11 @@ const (
 	// PortMappingProtocolSCTP specifies SCTP protocol
 	PortMappingProtocolSCTP PortMappingProtocol = "SCTP"
 )
+
+// NodeResources represents the node resources (CPU/Memory)
+type NodeResources struct {
+	// The maximum amount of memory the node can use.
+	Memory resource.Quantity `json:"memory,omitempty"`
+	// Specify how much of the available CPU resources a node can use
+	Cpus resource.Quantity `json:"cpus,omitempty"`
+}

pkg/cluster/internal/providers/docker/provision.go

@@ -178,9 +178,10 @@ func runArgsForNode(node *config.Node, clusterIPFamily config.ClusterIPFamily, n
 		args...,
 	)
 
-	// convert mounts and port mappings to container run args
+	// convert mounts, port mappings and resource constraints to container run args
 	args = append(args, generateMountBindings(node.ExtraMounts...)...)
 	args = append(args, generatePortMappings(clusterIPFamily, node.ExtraPortMappings...)...)
+	args = append(args, generateNodeConstraints(node.Constraints)...)
 
 	// finally, specify the image to run
 	return append(args, node.Image)
@@ -311,3 +312,21 @@ func generatePortMappings(clusterIPFamily config.ClusterIPFamily, portMappings .
 	}
 	return args
 }
+
+// generateNodeConstraints converts the nodesConstraints to a list of args for docker
+// https://docs.docker.com/config/containers/resource_constraints/
+func generateNodeConstraints(resources config.NodeResources) []string {
+	var args []string
+	if resources.Cpus.Sign() > 0 {
+		args = append(args, fmt.Sprintf("--cpus=%s", resources.Cpus.String()))
+	}
+
+	if resources.Memory.Sign() > 0 {
+		args = append(args, fmt.Sprintf("--memory=%s", resources.Memory.String()))
+		// prevent a container from using swap because we want to emulate a real node
+		// https://docs.docker.com/config/containers/resource_constraints/#prevent-a-container-from-using-swap
+		args = append(args, fmt.Sprintf("--memory-swap=%s", resources.Memory.String()))
+	}
+
+	return args
+}

pkg/internal/apis/config/types.go

@@ -16,6 +16,10 @@ limitations under the License.
 
 package config
 
+import (
+	"k8s.io/apimachinery/pkg/api/resource"
+)
+
 // Cluster contains kind cluster configuration
 type Cluster struct {
 	// Nodes contains the list of nodes defined in the `kind` Cluster
@@ -89,6 +93,9 @@ type Node struct {
 	// KubeadmConfigPatchesJSON6902 are applied to the generated kubeadm config
 	// as patchesJson6902 to `kustomize build`
 	KubeadmConfigPatchesJSON6902 []PatchJSON6902
+
+	// Constraints describes the node resources constraints
+	Constraints NodeResources
 }
 
 // NodeRole defines possible role for nodes in a Kubernetes cluster managed by `kind`
@@ -222,3 +229,11 @@ const (
 	// PortMappingProtocolSCTP specifies SCTP protocol
 	PortMappingProtocolSCTP PortMappingProtocol = "SCTP"
 )
+
+// NodeResources represents the node resources (CPU/Memory)
+type NodeResources struct {
+	// The maximum amount of memory the node can use.
+	Memory resource.Quantity
+	// Specify how much of the available CPU resources a node can use.
+	Cpus resource.Quantity
+}

pkg/internal/apis/config/validate.go

@@ -19,6 +19,8 @@ package config
 import (
 	"net"
 
+	"k8s.io/apimachinery/pkg/api/resource"
+
 	"sigs.k8s.io/kind/pkg/errors"
 )
 
@@ -101,6 +103,17 @@ func (n *Node) Validate() error {
 		}
 	}
 
+	// validate node resource constraints
+	if n.Constraints.Cpus.Sign() < 0 {
+		errs = append(errs, errors.New("invalid number of Cpus"))
+	}
+
+	// minimum memory size is 4m
+	minMemory := resource.MustParse("4m")
+	if n.Constraints.Memory.Sign() != 0 && n.Constraints.Memory.Cmp(minMemory) < 0 {
+		errs = append(errs, errors.New("invalid Memory Size (minimum 4m)"))
+	}
+
 	if len(errs) > 0 {
 		return errors.NewAggregate(errs)
 	}

pkg/internal/apis/config/validate_test.go

@@ -19,6 +19,8 @@ package config
 import (
 	"testing"
 
+	"k8s.io/apimachinery/pkg/api/resource"
+
 	"sigs.k8s.io/kind/pkg/errors"
 )
 
@@ -107,6 +109,21 @@ func TestClusterValidate(t *testing.T) {
 			}(),
 			ExpectErrors: 1,
 		},
+		{
+			Name: "wrong resources constraints node",
+			Cluster: func() Cluster {
+				c := Cluster{}
+				SetDefaultsCluster(&c)
+				n, n2 := Node{}, Node{}
+				SetDefaultsNode(&n)
+				SetDefaultsNode(&n2)
+				n.Constraints.Cpus = resource.MustParse("-12")
+				n.Constraints.Memory = resource.MustParse("1m")
+				c.Nodes = []Node{n, n2}
+				return c
+			}(),
+			ExpectErrors: 1,
+		},
 	}
 
 	for _, tc := range cases {
@@ -202,6 +219,24 @@ func TestNodeValidate(t *testing.T) {
 			}(),
 			ExpectErrors: 1,
 		},
+		{
+			TestName: "Negative CPU constraint",
+			Node: func() Node {
+				cfg := newDefaultedNode(ControlPlaneRole)
+				cfg.Constraints.Cpus = resource.MustParse("-12")
+				return cfg
+			}(),
+			ExpectErrors: 1,
+		},
+		{
+			TestName: "Minimum value for memory constraint",
+			Node: func() Node {
+				cfg := newDefaultedNode(ControlPlaneRole)
+				cfg.Constraints.Memory = resource.MustParse("2m")
+				return cfg
+			}(),
+			ExpectErrors: 1,
+		},
 		{
 			TestName: "Invalid HostPort",
 			Node: func() Node {

site/content/docs/user/quick-start.md

@@ -361,6 +361,25 @@ networking:
   ipFamily: ipv6
 ```
 
+#### Limit node resources
+You can set CPU and memory limits for your cluster nodes in the configuration file.
+
+```yaml
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+nodes:
+# the control plane node
+- role: control-plane
+  constraints:
+    memory: "200m"
+    cpus: "2"
+- role: worker
+  constraints:
+    memory: "100m"
+    cpus: "1"
+```
+
+
 ### Configure kind to use a proxy
 If you are running kind in an environment that requires a proxy, you may need to configure kind to use it.