feat(amazon-vpc-k8s-cni): kubelet --max-pods setting

This prevents kubelets from trying to scheduling more pods than available IPs per node when amazon-vpc-k8s-cni is enabled

core/controlplane/config/amazon_vpc.go

@@ -1 +1,44 @@
 package config
+
+import (
+	"fmt"
+	"github.com/aws/amazon-vpc-cni-k8s/pkg/awsutils"
+	"github.com/kubernetes-incubator/kube-aws/node"
+)
+
+type AmazonVPC struct {
+	Enabled bool `yaml:"enabled"`
+}
+
+func (a AmazonVPC) MaxPodsScript() node.UploadedFileContent {
+	script := `#!/usr/bin/env bash
+
+set -e
+
+# According to https://github.com/aws/amazon-vpc-cni-k8s#eni-allocation
+ips_per_eni=30
+
+declare -A instance_eni_available
+`
+
+	for it, num := range awsutils.InstanceENIsAvailable {
+		script = script + fmt.Sprintf(`instance_eni_available["%s"]=%d
+`, it, num)
+	}
+	script = script + `
+
+instance_type=$(curl http://169.254.169.254/latest/meta-data/instance-type)
+
+enis=${instance_eni_available["$instance_type"]}
+
+if [ "" == "$enis" ]; then
+  echo "unsupported instance type: $instance_type" 1>&2
+  exit 1
+fi
+
+max_pods=$(( (enis * (ips_per_eni - 1)) + 2 ))
+
+printf $max_pods
+`
+	return node.NewUploadedFileContent([]byte(script))
+}

core/controlplane/config/config.go

@@ -794,10 +794,6 @@ type Networking struct {
 	SelfHosting SelfHosting `yaml:"selfHosting"`
 }
 
-type AmazonVPC struct {
-	Enabled bool `yaml:"enabled"`
-}
-
 type SelfHosting struct {
 	Type            string      `yaml:"type"`
 	Typha           bool        `yaml:"typha"`

core/controlplane/config/templates/cloud-config-controller

@@ -346,6 +346,7 @@ coreos:
         {{- end }}
         {{- if .Kubernetes.Networking.AmazonVPC.Enabled }}
         --node-ip=$$(curl http://169.254.169.254/latest/meta-data/local-ipv4) \
+        --max-pods=$$(/opt/bin/aws-k8s-cni-max-pods) \
         {{- end }}
         $KUBELET_OPTS \
         "
@@ -4849,6 +4850,12 @@ write_files:
 {{end}}
 
 {{if .Kubernetes.Networking.AmazonVPC.Enabled }}
+  - path: /opt/bin/aws-k8s-cni-max-pods
+    owner: root:root
+    permissions: 0755
+    encoding: gzip+base64
+    content: {{.Kubernetes.Networking.AmazonVPC.MaxPodsScript.ToGzip.ToBase64}}
+
   - path: /srv/kubernetes/manifests/aws-k8s-cni.yaml
     content: |
       ---

node/uploaded_file.go

@@ -9,36 +9,36 @@ import (
 
 type UploadedFile struct {
 	Path    string
-	Content uploadedFileContent
+	Content UploadedFileContent
 }
 
-type uploadedFileContent struct {
+type UploadedFileContent struct {
 	bytes []byte
 }
 
-func NewUploadedFileContent(bytes []byte) uploadedFileContent {
-	return uploadedFileContent{
+func NewUploadedFileContent(bytes []byte) UploadedFileContent {
+	return UploadedFileContent{
 		bytes: bytes,
 	}
 }
 
-func (c uploadedFileContent) ToBase64() uploadedFileContent {
+func (c UploadedFileContent) ToBase64() UploadedFileContent {
 	bytes := []byte(base64.StdEncoding.EncodeToString(c.bytes))
-	return uploadedFileContent{
+	return UploadedFileContent{
 		bytes: bytes,
 	}
 }
 
-func (c uploadedFileContent) ToGzip() uploadedFileContent {
+func (c UploadedFileContent) ToGzip() UploadedFileContent {
 	bytes, err := gzipcompressor.BytesToBytes(c.bytes)
 	if err != nil {
 		panic(fmt.Errorf("Unexpected error in ToGzip: %v", err))
 	}
-	return uploadedFileContent{
+	return UploadedFileContent{
 		bytes: bytes,
 	}
 }
 
-func (c uploadedFileContent) String() string {
+func (c UploadedFileContent) String() string {
 	return string(c.bytes)
 }