Implement resource constraints on nodes

pkg/apis/config/v1alpha3/types.go

@@ -75,6 +75,9 @@ type Node struct {
 	// ExtraPortMappings describes additional port mappings for the node container
 	// binded to a host Port
 	ExtraPortMappings []cri.PortMapping `json:"extraPortMappings,omitempty"`
+
+	// Constraints describe the node resources constraints
+	Constraints NodeResources `json:"constraints,omitempty"`
 }
 
 // NodeRole defines possible role for nodes in a Kubernetes cluster managed by `kind`
@@ -138,3 +141,11 @@ type PatchJSON6902 struct {
 	// Patch should contain the contents of the json patch as a string
 	Patch string `json:"patch"`
 }
+
+// NodeResources represents the node resources (CPU/Memory)
+type NodeResources struct {
+	// The maximum amount of memory the node can use.
+	Memory string `json:"memory,omitempty"`
+	// Specify how much of the available CPU resources a node can use
+	Cpus string `json:"cpus,omitempty"`
+}

pkg/internal/apis/config/types.go

@@ -74,6 +74,9 @@ type Node struct {
 	// ExtraPortMappings describes additional port mappings for the node container
 	// binded to a host Port
 	ExtraPortMappings []cri.PortMapping
+
+	// Constraints describe the node resources constraints
+	Constraints NodeResources
 }
 
 // NodeRole defines possible role for nodes in a Kubernetes cluster managed by `kind`
@@ -137,3 +140,11 @@ type PatchJSON6902 struct {
 	// Patch should contain the contents of the json patch as a string
 	Patch string
 }
+
+// NodeResources represents the node resources (CPU/Memory)
+type NodeResources struct {
+	// The maximum amount of memory the node can use.
+	Memory string
+	// Specify how much of the available CPU resources a node can use.
+	Cpus string
+}

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

@@ -173,9 +173,10 @@ func runArgsForNode(node *config.Node, name string, args []string) []string {
 		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(node.ExtraPortMappings...)...)
+	args = append(args, generateNodeConstraints(node.Constraints)...)
 
 	// finally, specify the image to run
 	return append(args, node.Image)
@@ -293,3 +294,17 @@ func generatePortMappings(portMappings ...cri.PortMapping) []string {
 	}
 	return args
 }
+
+// generateNodeConstraints converts the nodesConstraints to a list of args for docker
+// ref https://docs.docker.com/config/containers/resource_constraints/
+func generateNodeConstraints(resources config.NodeResources) []string {
+	var args []string
+	if len(resources.Cpus) > 0 {
+		args = append(args, fmt.Sprintf("--cpus=%s", (resources.Cpus)))
+	}
+	if len(resources.Memory) > 0 {
+		args = append(args, fmt.Sprintf("--memory=%s", (resources.Memory)))
+	}
+
+	return args
+}

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

@@ -344,6 +344,27 @@ nodes:
 - role: worker
 ```
 
+#### Limit node resources
+`kind` implements [docker resource constraints][docker resource constraints],
+so you can limit the memory and  CPU used by any cluster node.
+
+```yaml
+kind: Cluster
+apiVersion: kind.sigs.k8s.io/v1alpha3
+nodes:
+# the control plane node
+- role: control-plane
+  constraints:
+    memory: "200m"
+    cpu: "2"
+- role: worker
+- role: worker
+  constraints:
+    memory: "100m"
+    cpu: "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.
 
@@ -409,3 +430,4 @@ kind, the Kubernetes cluster itself, etc.
 [Private Registries]: /docs/user/private-registries
 [customize control plane with kubeadm]: https://kubernetes.io/docs/setup/independent/control-plane-flags/
 [docker enable ipv6]: https://docs.docker.com/v17.09/engine/userguide/networking/default_network/ipv6/
+[docker resource constraints]: https://docs.docker.com/config/containers/resource_constraints/