Security groups for pods - Amazon EKS

Security groups for pods

Security groups for pods integrate Amazon EC2 security groups with Kubernetes pods. You can use Amazon EC2 security groups to define rules that allow inbound and outbound network traffic to and from pods that you deploy to nodes running on many Amazon EC2 instance types. For a detailed explanation of this capability, see the Introducing security groups for pods blog post.

Considerations

Before deploying security groups for pods, consider the following limits and conditions:

  • Your Amazon EKS cluster must be running Kubernetes version 1.17 and Amazon EKS platform version eks.3 or later. You can't use security groups for pods on Kubernetes clusters that you deployed to Amazon EC2.

  • Traffic flow to and from pods with associated security groups are not subjected to Calico network policy enforcement and are limited to Amazon EC2 security group enforcement only. Community effort is underway to remove this limitation.

  • Security groups for pods can't be used with pods deployed to Fargate.

  • Security groups for pods can't be used with Windows nodes.

  • Security groups for pods are supported by most Nitro-based Amazon EC2 instance families, including the m5, c5, r5, p3, m6g, cg6, and r6g instance families. The t3 instance family is not supported. For a complete list of supported instances, see Amazon EC2 supported instances and branch network interfaces. Your nodes must be one of the supported instance types.

  • Source NAT is disabled for outbound traffic from pods with assigned security groups so that outbound security group rules are applied. To access the internet, pods with assigned security groups must be launched on nodes that are deployed in a private subnet configured with a NAT gateway or instance. Pods with assigned security groups deployed to public subnets are not able to access the internet.

  • If you're using custom networking and security groups for pods together, the security group specified by security groups for pods is used instead of the security group specified in the ENIconfig.

Deploy security groups for pods

To deploy security groups for pods

  1. Check your current CNI plug-in version with the following command.

    kubectl describe daemonset aws-node --namespace kube-system | grep Image | cut -d "/" -f 2

    The output is similar to the following output.

    amazon-k8s-cni:<1.7.1>

    If your CNI plug-in version is earlier than 1.7.1, then upgrade your CNI plug-in to version 1.7.1 or later. For more information, see Amazon VPC CNI plugin for Kubernetes upgrades.

  2. Add the AmazonEKSVPCResourceController managed policy to the cluster role that is associated with your Amazon EKS cluster. The policy allows the role to manage network interfaces, their private IP addresses, and their attachment and detachment to and from instances. The following command adds the policy to a cluster role named <eksClusterRole>.

    aws iam attach-role-policy \ --policy-arn arn:aws:iam::aws:policy/AmazonEKSVPCResourceController \ --role-name <eksClusterRole>
  3. Enable the CNI plug-in to manage network interfaces for pods by setting the ENABLE_POD_ENI variable to true in the aws-node DaemonSet. Once this setting is set to true, for each node in the cluster the plug-in adds a label with the value vpc.amazonaws.com/has-trunk-attached=true. The VPC resource controller creates and attaches one special network interface called a trunk network interface with the description aws-k8s-trunk-eni.

    kubectl set env daemonset aws-node -n kube-system ENABLE_POD_ENI=true
    Note

    The trunk network interface is included in the maximum number of network interfaces supported by the instance type. For a list of the maximum number of interfaces supported by each instance type, see IP addresses per network interface per instance type in the Amazon EC2 User Guide for Linux Instances. If your node already has the maximum number of standard network interfaces attached to it then the VPC resource controller will reserve a space. You will have to scale down your running pods enough for the controller to detach and delete a standard network interface, create the trunk network interface, and attach it to the instance.

    You can see which of your nodes have aws-k8s-trunk-eni set to true with the following command.

    kubectl get nodes -o wide -l vpc.amazonaws.com/has-trunk-attached=true

    Once the trunk network interface is created, pods can be assigned secondary IP addresses from the trunk or standard network interfaces. The trunk interface is automatically deleted if the node is deleted.

    When you deploy a security group for a pod in a later step, the VPC resource controller creates a special network interface called a branch network interface with a description of aws-k8s-branch-eni and associates the security groups to it. Branch network interfaces are created in addition to the standard and trunk network interfaces attached to the node. If are you using liveness or readiness probes, you also need to disable TCP early demux, so that the kubelet can connect to pods on branch network interfaces via TCP. To disable TCP early demux, run the following command:

    kubectl edit ds aws-node -n kube-system

    Under the initContainers section, change the value of DISABLE_TCP_EARLY_DEMUX from false to true, and save the file.

  4. Create a namespace to deploy resources to.

    kubectl create namespace <my-namespace>
  5. Deploy an Amazon EKS SecurityGroupPolicy to your cluster.

    1. Save the following example security policy to a file named <my-security-group-policy.yaml>. You can replace podSelector with serviceAccountSelector if you'd rather select pods based on service account labels. You must specify one selector or the other. An empty podSelector (example: podSelector: {}) selects all pods in the namespace. An empty serviceAccountSelector selects all service accounts in the namespace. You must specify 1-5 security group IDs for groupIds. If you specify more than one ID, then the combination of all the rules in all the security groups are effective for the selected pods.

      apiVersion: vpcresources.k8s.aws/v1beta1 kind: SecurityGroupPolicy metadata: name: <my-security-group-policy> namespace: <my-namespace> spec: <podSelector>: matchLabels: <role>: <my-role> securityGroups: groupIds: - <sg-abc123>
      Important
      • The security groups that you specify in the policy must exist. If they don't exist, then, when you deploy a pod that matches the selector, your pod remains stuck in the creation process. If you describe the pod, you'll see an error message similar to the following one: An error occurred (InvalidSecurityGroupID.NotFound) when calling the CreateNetworkInterface operation: The securityGroup ID '<sg-abc123>' does not exist.

      • The security group must allow inbound communication from the cluster security group (for kubelet) over any ports you've configured probes for.

      • The security group must allow outbound communication to the cluster security group (for CoreDNS) over TCP and UDP port 53. The cluster security group must also allow inbound TCP and UDP port 53 communication from all security groups associated to pods.

    2. Deploy the policy.

      kubectl apply -f <my-security-group-policy.yaml>
  6. Deploy a sample application with a label that matches the <my-role> value for <podSelector> that you specified in the previous step.

    1. Save the following contents to a file.

      apiVersion: apps/v1 kind: Deployment metadata: name: <my-deployment> namespace: <my-namespace> labels: app: <my-app> spec: replicas: <1> selector: matchLabels: app: <my-app> template: metadata: labels: app: <my-app> role: <my-role> spec: containers: - name: <my-container> image: <my-image> ports: - containerPort: <80>
    2. Deploy the application with the following command. When you deploy the application, the CNI plug-in matches the role label and the security groups that you specified in the previous step are applied to the pod.

      kubectl apply -f <file-name-you-used-in-previous-step.yaml>
      Note
      • If your pod is stuck in the Waiting state and you see Insufficient permissions: Unable to create Elastic Network Interface. when you describe the pod, confirm that you added the IAM policy to the IAM cluster role in a previous step.

      • If your pod is stuck in the Pending state, confirm that your node instance type is listed in Amazon EC2 supported instances and branch network interfaces and that that the maximum number of branch network interfaces supported by the instance type multiplied times the number of nodes in your node group hasn't already been met. For example, an m5.large instance supports nine branch network interfaces. If your node group has five nodes, then a maximum of 45 branch network interfaces can be created for the node group. The 46th pod that you attempt to deploy will sit in Pending state until another pod that has associated security groups is deleted.

      If you run kubectl describe pod <my-deployment-xxxxxxxxxx-xxxxx> -n <my-namespace> and see a message similar to the following message, then it can be safely ignored. This message might appear when the CNI plug-in tries to set up host networking and fails while the network interface is being created. The CNI plug-in logs this event until the network interface is created.

      Failed to create pod sandbox: rpc error: code = Unknown desc = failed to set up sandbox container "<e24268322e55c8185721f52df6493684f6c2c3bf4fd59c9c121fd4cdc894579f>" network for pod "<my-deployment-59f5f68b58-c89wx>": networkPlugin cni failed to set up pod "<my-deployment-59f5f68b58-c89wx_my-namespace>" network: add cmd: failed to assign an IP address to container

      You cannot exceed the maximum number of pods that can be run on the instance type. For a list of the maximum number of pods that you can run on each instance type, see eni-max-pods.txt on GitHub. When you delete a pod that has associated security groups, or delete the node that the pod is running on, the VPC resource controller deletes the branch network interface. If you delete a cluster with pods using pods for security groups, then the controller does not delete the branch network interfaces, so you'll need to delete them yourself.

Amazon EC2 supported instances and branch network interfaces

The following table lists the number of branch network interfaces that you can use with each supported Amazon EC2 instance type.

Instance type Branch network interfaces
a1.medium 10
a1.large 9
a1.xlarge 18
a1.2xlarge 38
a1.4xlarge 54
a1.metal 54
c5.large 9
c5.xlarge 18
c5.2xlarge 38
c5.4xlarge 54
c5.9xlarge 54
c5.12xlarge 54
c5.18xlarge 107
c5.24xlarge 107
c5.metal 107
c5a.large 9
c5a.xlarge 18
c5a.2xlarge 38
c5a.4xlarge 54
c5a.8xlarge 54
c5a.12xlarge 54
c5a.16xlarge 107
c5a.24xlarge 107
c5d.large 9
c5d.xlarge 18
c5d.2xlarge 38
c5d.4xlarge 54
c5d.9xlarge 54
c5d.12xlarge 54
c5d.18xlarge 107
c5d.24xlarge 107
c5d.metal 107
c5n.large 9
c5n.xlarge 18
c5n.2xlarge 38
c5n.4xlarge 54
c5n.9xlarge 54
c5n.18xlarge 107
c5n.metal 107
c6g.medium 4
c6g.large 9
c6g.xlarge 18
c6g.2xlarge 38
c6g.4xlarge 54
c6g.8xlarge 54
c6g.12xlarge 54
c6g.16xlarge 107
c6g.metal 107
g4dn.xlarge 39
g4dn.2xlarge 39
g4dn.4xlarge 59
g4dn.8xlarge 58
g4dn.12xlarge 54
g4dn.16xlarge 118
g4dn.metal 107
i3en.large 5
i3en.xlarge 12
i3en.2xlarge 28
i3en.3xlarge 38
i3en.6xlarge 54
i3en.12xlarge 114
i3en.24xlarge 107
i3en.metal 107
inf1.xlarge 38
inf1.2xlarge 38
inf1.6xlarge 54
inf1.24xlarge 107
m5.large 9
m5.xlarge 18
m5.2xlarge 38
m5.4xlarge 54
m5.8xlarge 54
m5.12xlarge 54
m5.16xlarge 107
m5.24xlarge 107
m5.metal 107
m5a.large 9
m5a.xlarge 18
m5a.2xlarge 38
m5a.4xlarge 54
m5a.8xlarge 54
m5a.12xlarge 54
m5a.16xlarge 107
m5a.24xlarge 107
m5ad.large 9
m5ad.xlarge 18
m5ad.2xlarge 38
m5ad.4xlarge 54
m5ad.8xlarge 54
m5ad.12xlarge 54
m5ad.16xlarge 107
m5ad.24xlarge 107
m5d.large 9
m5d.xlarge 18
m5d.2xlarge 38
m5d.4xlarge 54
m5d.8xlarge 54
m5d.12xlarge 54
m5d.16xlarge 107
m5d.24xlarge 107
m5d.metal 107
m5dn.large 9
m5dn.xlarge 18
m5dn.2xlarge 38
m5dn.4xlarge 54
m5dn.8xlarge 54
m5dn.12xlarge 54
m5dn.16xlarge 107
m5dn.24xlarge 107
m5n.large 9
m5n.xlarge 18
m5n.2xlarge 38
m5n.4xlarge 54
m5n.8xlarge 54
m5n.12xlarge 54
m5n.16xlarge 107
m5n.24xlarge 107
m6g.medium 4
m6g.large 9
m6g.xlarge 18
m6g.2xlarge 38
m6g.4xlarge 54
m6g.8xlarge 54
m6g.12xlarge 54
m6g.16xlarge 107
m6g.metal 107
p3.2xlarge 38
p3.8xlarge 54
p3.16xlarge 114
p3dn.24xlarge 107
r5.large 9
r5.xlarge 18
r5.2xlarge 38
r5.4xlarge 54
r5.8xlarge 54
r5.12xlarge 54
r5.16xlarge 107
r5.24xlarge 107
r5.metal 107
r5a.large 9
r5a.xlarge 18
r5a.2xlarge 38
r5a.4xlarge 54
r5a.8xlarge 54
r5a.12xlarge 54
r5a.16xlarge 107
r5a.24xlarge 107
r5ad.large 9
r5ad.xlarge 18
r5ad.2xlarge 38
r5ad.4xlarge 54
r5ad.8xlarge 54
r5ad.12xlarge 54
r5ad.16xlarge 107
r5ad.24xlarge 107
r5d.large 9
r5d.xlarge 18
r5d.2xlarge 38
r5d.4xlarge 54
r5d.8xlarge 54
r5d.12xlarge 54
r5d.16xlarge 107
r5d.24xlarge 107
r5d.metal 107
r5dn.large 9
r5dn.xlarge 18
r5dn.2xlarge 38
r5dn.4xlarge 54
r5dn.8xlarge 54
r5dn.12xlarge 54
r5dn.16xlarge 107
r5dn.24xlarge 107
r5n.large 9
r5n.xlarge 18
r5n.2xlarge 38
r5n.4xlarge 54
r5n.8xlarge 54
r5n.12xlarge 54
r5n.16xlarge 107
r5n.24xlarge 107
r6g.medium 4
r6g.large 9
r6g.xlarge 18
r6g.2xlarge 38
r6g.4xlarge 54
r6g.8xlarge 54
r6g.12xlarge 54
r6g.16xlarge 107
z1d.large 13
z1d.xlarge 28
z1d.2xlarge 58
z1d.3xlarge 54
z1d.6xlarge 54
z1d.12xlarge 107
z1d.metal 107