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Security

Security Notes for Kubernetes

SSH Access

SSH is allowed to the masters and the nodes, by default from anywhere. However, no public key will be installed. You can use instead use ec2 instance connect, which is installed in the default AMIs.

If you want to use a fixed key for the cluster, you have to specify --ssh-public-key <public key file> on the kops create cluster command or use kops create sshpublickey. You can also set the following in the cluster spec:

spec:
  sshKeyName: <ssh key pair>

An EC2 key pair with the name<ssh key pair> has to already exist.

By default, SSH is allowed from any address. You can restrict from where SSH connections can be made by setting either spec.sshAccess in the cluster spec or using kops create cluster --ssh-access.

To change the SSH public key on an existing cluster:

  • kops delete sshpublickey --name <clustername> sshpublickey
  • kops create sshpublickey --name <clustername> sshpublickey -i ~/.ssh/newkey.pub
  • kops update <clustername> --yes to reconfigure the launch templates.
  • kops rolling-update cluster --name <clustername> --yes to roll all the machines so they have the new key.

Docker Configuration

If you are using a private registry such as quay.io, you may be familiar with the inconvenience of managing the imagePullSecrets for each namespace. It can also be a pain to use kOps Hooks with private images. To configure docker on all nodes with access to one or more private registries:

  • kops create secret --name <clustername> dockerconfig -f ~/.docker/config.json
  • kops rolling-update cluster --name <clustername> --yes to immediately roll all the machines so they have the new key (optional)

This stores the config.json in /root/.docker/config.json on all nodes (include masters) so that both Kubernetes and system containers may use registries defined in it.

Note that this will also work when using containerd.

Instance IAM roles

All Pods running on your cluster have access to underlying instance IAM role. Currently, permission scope is quite broad. See iam_roles.md for details and ways to mitigate that.