Dynamic Kubernetes Cluster Registration

With dynamic Kubernetes cluster registration, you can manage the Kubernetes clusters connected to your Teleport cluster without needing to modify the configuration file of an individual Kubernetes Service instance.

Dynamic Kubernetes cluster registration is useful when you have deployed multiple Kubernetes Service instances or need to regularly reconfigure access to Kubernetes clusters in your infrastructure.

In this guide, we will show you how to set up dynamic Kubernetes cluster registration, then create, list, update, and delete Kubernetes clusters via tctl.

Prerequisites

• A Linux host where you will install the Teleport Kubernetes Service.

  Our teleport-kube-agent Helm chart does not support dynamic Kubernetes cluster registration.

• A Kubernetes cluster to join to your Teleport cluster. You must have permissions to create namespaces, secrets, service accounts, cluster roles, and cluster role bindings in the cluster.

tsh login --proxy=teleport.example.com [email protected]
tctl status
Cluster  teleport.example.com
Version  12.1.1
CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

tsh login --proxy=myinstance.teleport.sh [email protected]
tctl status
Cluster  myinstance.teleport.sh
Version  12.1.2
CA pin   sha256:sha-hash-here

Step 1/3. Set up the Teleport Kubernetes Service

The Teleport Kubernetes Service proxies traffic from Teleport users to a Kubernetes API server so you can take advantage of passwordless authentication, role-based access controls, audit logging, and other Teleport features in order to manage access to Kubernetes.

In this step, you will install the Teleport Kubernetes Service on a Linux host and configure it to access any Kubernetes cluster you register with your Teleport cluster.

Get a join token

Establish trust between your Teleport cluster and your new Kubernetes Service instance by creating a join token:

tctl nodes add --roles=kube
The invite token: abcd123-insecure-do-not-use-this
This token will expire in 30 minutes.
Run this on the new node to join the cluster:
> teleport start \
   --roles=kube \
   --token=abcd123-insecure-do-not-use-this \
   --ca-pin=sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678 \
   --auth-server=192.0.2.255:3025
Please note:
  - This invitation token will expire in 30 minutes
  - 192.0.2.255:3025 must be reachable from the new node

Copy the token and keep it somewhere safe so you can use it when running the Teleport Kubernetes Service.

Install the Teleport Kubernetes Service

Install the Teleport Kubernetes Service on your Linux host:

Use the appropriate commands for your environment to install your package.

Download Teleport's PGP public key
sudo curl https://apt.releases.teleport.dev/gpg \-o /usr/share/keyrings/teleport-archive-keyring.asc
Source variables about OS version
source /etc/os-release
Add the Teleport APT repository for v12. You'll need to update this
file for each major release of Teleport.
Note: if using a fork of Debian or Ubuntu you may need to use '$ID_LIKE'
and the codename your distro was forked from instead of '$ID' and '$VERSION_CODENAME'.
Supported versions are listed here: https://github.com/gravitational/teleport/blob/master/build.assets/tooling/cmd/build-os-package-repos/runners.go#L42-L67
echo "deb [signed-by=/usr/share/keyrings/teleport-archive-keyring.asc] \https://apt.releases.teleport.dev/${ID?} ${VERSION_CODENAME?} stable/v12" \| sudo tee /etc/apt/sources.list.d/teleport.list > /dev/null
sudo apt-get update
sudo apt-get install teleport

Source variables about OS version
source /etc/os-release
Add the Teleport YUM repository for v12. You'll need to update this
file for each major release of Teleport.
Note: if using a fork of RHEL/CentOS or Amazon Linux you may need to use '$ID_LIKE'
and the codename your distro was forked from instead of '$ID'
Supported versions are listed here: https://github.com/gravitational/teleport/blob/master/build.assets/tooling/cmd/build-os-package-repos/runners.go#L133-L153
sudo yum-config-manager --add-repo $(rpm --eval "https://yum.releases.teleport.dev/$ID/$VERSION_ID/Teleport/%{_arch}/stable/v12/teleport.repo")
sudo yum install teleport
Tip: Add /usr/local/bin to path used by sudo (so 'sudo tctl users add' will work as per the docs)
echo "Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin" > /etc/sudoers.d/secure_path
Optional:  Use DNF on newer distributions
$ sudo dnf config-manager --add-repo https://rpm.releases.teleport.dev/teleport.repo
$ sudo dnf install teleport

curl https://get.gravitational.com/teleport-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
shasum -a 256 teleport-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
cd teleport
sudo ./install

dpkg -i ~/Downloads/teleport-ent_12.1.1_$SYSTEM-ARCH.deb
Selecting previously unselected package teleport-ent.
(Reading database ... 30810 files and directories currently installed.)
Preparing to unpack teleport-ent_12.1.1_$SYSTEM_ARCH.deb ...
Unpacking teleport-ent 12.1.1 ...
Setting up teleport-ent 12.1.1 ...

rpm -i ~/Downloads/teleport-ent-12.1.1.$SYSTEM-ARCH.rpm
warning: teleport-ent-12.1.1.$SYSTEM-ARCH.rpm: Header V4 RSA/SHA512 Signature, key ID 6282c411: NOKEY

curl https://get.gravitational.com/teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
shasum -a 256 teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-bin.tar.gz
cd teleport-ent
sudo ./install

curl https://get.gravitational.com/teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-fips-bin.tar.gz.sha256
<checksum> <filename>
curl -O https://cdn.teleport.dev/teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-fips-bin.tar.gz
shasum -a 256 teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-fips-bin.tar.gz
Verify that the checksums match
tar -xvf teleport-ent-v12.1.1-linux-$SYSTEM-ARCH-fips-bin.tar.gz
cd teleport-ent
sudo ./install

Configure the Teleport Kubernetes Service

On the host where you will run the Teleport Kubernetes Service, run the following command to create a base configuration for your Teleport instance, assigning PROXY_SERVICE to the host and port of your Teleport Proxy Service or Teleport Cloud tenant and TOKEN to the join token we created earlier:

e.g., teleport.example.com:443
PROXY_SERVICE=proxy-addr
e.g., abcd123-insecure-do-not-use-this;
TOKEN=join-token;
sudo teleport configure \--proxy=${PROXY_SERVICE?} \--roles=kube \--token=${TOKEN?} \-o file

Edit your configuration file at /etc/teleport.yaml to include the following:

kubernetes_service:
  enabled: "yes"
  resources:
  - labels:
      "*": "*"

This configuration enables your Kubernetes Service instance to connect to any Kubernetes clusters you register with your Teleport cluster. This is because the resources[0].labels field includes the wildcard pattern ("*": "*"), which allows this Kubernetes Service instance to connect to Kubernetes cluster resources with any label key or value.

resources:
- labels:
    "env": "prod"
    "region": "us-east-2"
- labels:
    "env": "test"
    "region": "us-west-1"

Run the Teleport Kubernetes Service

On the host where you will run the Teleport Kubernetes Service, execute the following command, depending on whether you installed Teleport using a package manager or via a TAR archive:

sudo systemctl start teleport

sudo teleport install systemd --output=/etc/systemd/system/teleport.service;
sudo systemctl enable teleport;
sudo systemctl start teleport;

Step 2/3. Authorize your user

To enable dynamic Kubernetes cluster registration in Teleport, you will need to authorize your user to access the Kubernetes clusters you want to register with Teleport. We will configure this access in this step, both in Teleport and on your Kubernetes cluster.

Allow access to your Kubernetes cluster

Ensure that you are in the correct Kubernetes context for the cluster you would like to enable access to.

Retrieve all available contexts:

kubectl config get-contexts

Switch to your context, replacing CONTEXT_NAME with the name of your chosen context:

kubectl config use-context CONTEXT_NAME
Switched to context CONTEXT_NAME

Kubernetes authentication

To authenticate to a Kubernetes cluster via Teleport, your Teleport roles must allow access as at least one Kubernetes user or group. Ensure that you have a Teleport role that grants access to the cluster you plan to interact with.

Run the following command to get the Kubernetes user for your current context:

kubectl config view \-o jsonpath="{.contexts[?(@.name==\"$(kubectl config current-context)\")].context.user}"

Create a file called kube-access.yaml with the following content, replacing USER with the output of the command above.

kind: role
metadata:
  name: kube-access
version: v6
spec:
  allow:
    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: pod
        namespace: "*"
        name: "*"
    kubernetes_groups:
    - viewers
    kubernetes_users:
    - USER
  deny: {}

Apply your changes:

tctl create -f kube-access.yaml

Assign the kube-access role to your Teleport user by running the following commands, depending on whether you authenticate as a local Teleport user or via the github, saml, or oidc authentication connectors:

tctl get users/$(tsh status -f json | jq -r '.active.username') > out.yaml

  roles:
   - access
   - auditor
   - editor
+  - kube-access

tctl create -f out.yaml

tctl get github/github --with-secrets > github.yaml

  teams_to_roles:
    - organization: octocats
      team: admins
      roles:
        - access
+       - kube-access

tctl create -f github.yaml

tctl get --with-secrets saml/mysaml > saml.yaml

  attributes_to_roles:
    - name: "groups"
      value: "my-group"
      roles:
        - access
+       - kube-access

tctl create -f saml.yaml

tctl get oidc/myoidc --with-secrets > oidc.yaml

  claims_to_roles:
    - name: "groups"
      value: "my-group"
      roles:
        - access
+       - kube-access

tctl create -f saml.yaml

Log out of your Teleport cluster and log in again to assume the new role.

Now that Teleport RBAC is configured, you can authenticate to your Kubernetes cluster via Teleport. To interact with your Kubernetes cluster, you will need to configure authorization within Kubernetes.

Kubernetes authorization

To configure authorization within your Kubernetes cluster, you need to create Kubernetes RoleBindings or ClusterRoleBindings that grant permissions to the subjects listed in kubernetes_users and kubernetes_groups.

For example, you can grant some limited read-only permissions to the viewers group used in the kube-access role defined above:

Create a file called viewers-bind.yaml with the following contents:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: viewers-crb
subjects:
- kind: Group
  # Bind the group "viewers", corresponding to the kubernetes_groups we assigned our "kube-access" role above
  name: viewers
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  # "view" is a default ClusterRole that grants read-only access to resources
  # See: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#user-facing-roles
  name: view
  apiGroup: rbac.authorization.k8s.io

Apply the ClusterRoleBinding with kubectl:

kubectl apply -f viewers-bind.yaml

Log out of Teleport and log in again.

Authorize your user to manage Kubernetes clusters

Teleport tracks Kubernetes clusters in your infrastructure via dynamic kube_cluster resources. To manage access to Kubernetes clusters with Teleport, your user will need permissions to manage these resources.

In the previous section, you authorized your user to access all Kubernetes clusters registered in your Teleport cluster. Now that you can access these clusters, create a role that enables you to manage them.

Create a role definition called kube-manager.yaml with the following content:

kind: role
metadata:
  name: kube-manager
spec:
  allow:
    rules:
    - resources:
      - kube_cluster
      verbs:
      - list
      - create
      - read
      - update
      - delete
version: v5

Create the role:

tctl create -f kube-manager.yaml

Assign the kube-manager role to your Teleport user by running the following commands, depending on whether you authenticate as a local Teleport user or via the github, saml, or oidc authentication connectors:

tctl get users/$(tsh status -f json | jq -r '.active.username') > out.yaml

  roles:
   - access
   - auditor
   - editor
+  - kube-manager

tctl create -f out.yaml

tctl get github/github --with-secrets > github.yaml

  teams_to_roles:
    - organization: octocats
      team: admins
      roles:
        - access
+       - kube-manager

tctl create -f github.yaml

tctl get --with-secrets saml/mysaml > saml.yaml

  attributes_to_roles:
    - name: "groups"
      value: "my-group"
      roles:
        - access
+       - kube-manager

tctl create -f saml.yaml

tctl get oidc/myoidc --with-secrets > oidc.yaml

  claims_to_roles:
    - name: "groups"
      value: "my-group"
      roles:
        - access
+       - kube-manager

tctl create -f saml.yaml

Log out of your Teleport cluster and log in again to assume the new role.

Step 3/3. Manage dynamic Kubernetes cluster resources

Now that your Teleport user has permissions to manage Kubernetes cluster resources, we will show you how to create, list, update, and delete them.

Create a kubeconfig

In this section, you will create a Kubernetes Config resource, or kubeconfig, that your Teleport cluster will use to authenticate to your Kubernetes cluster.

When you signed into Teleport earlier in this guide, tsh may have changed your Kubernetes context to one based on your Teleport cluster, so make sure you update your Kubernetes context to match the cluster you would like to connect to Teleport:

kubectl config get-contexts
Assign CONTEXT_NAME to your chosen context
kubectl config use-context CONTEXT_NAME

On your workstation, download Teleport's get-kubeconfig.sh script, which you will use to generate the kubeconfig:

curl -OL \https://raw.githubusercontent.com/gravitational/teleport/v12.1.1/examples/k8s-auth/get-kubeconfig.sh

The script creates a service account for the Teleport Kubernetes Service that can get Kubernetes pods as well as impersonate users, groups, and other service accounts. The Teleport Kubernetes Service uses this service account to manage access to resources in your Kubernetes cluster. The script also ensures that there is a Kubernetes Secret in your cluster to store service account credentials.

get-kubeconfig.sh creates a namespace called teleport for the resources it deploys, though you can choose a different name by assigning the TELEPORT_NAMESPACE environment variable in the shell where you run the script.

After creating resources, get-kubeconfig.sh writes a new kubeconfig to a file called kubeconfig in the directory where you run the script.

Run the get-kubeconfig.sh script:

bash get-kubeconfig.sh

The script is successful if you see this message:

Done!

Ignore the script's instructions to copy the generated kubeconfig file to the Teleport Proxy Service. In the next section, we will show you how to use the kubeconfig file when creating a dynamic kube_cluster resource.

Create a Kubernetes cluster resource

Define a kube_cluster resource with the following content in a file called kube_cluster.yaml:

kind: kube_cluster
version: v3
metadata:
  name: mycluster
spec:
  kubeconfig: |

The spec.kubeconfig field in the snippet above begins a multi-line string. Below, you will include the contents of the kubeconfig file as its value.

Since spec.kubeconfig must be a base64-encoded string, convert the kubeconfig file to base64, then indent it and add it to the kube_cluster.yaml resource definition using the following command:

printf "    %s" $(cat kubeconfig | base64) >> kube_cluster.yaml

kind: kube_cluster
version: v3
metadata:
  name: mycluster
  labels:
    env: prod
    team: dev
spec:
  kubeconfig: KUBECONFIG

kind: kube_cluster
version: v3
metadata:
  name: mycluster
spec:
  kubeconfig: KUBECONFIG
  dynamic_labels:
    region:
      period: "24h"
      command: ["python3", "get_region.py"]

To create the kube_cluster resource, run the following command:

tctl create kube_cluster.yaml
kubernetes cluster "mycluster" has been created

Access your new Kubernetes cluster

Instances of the Teleport Kubernetes Service watch for newly created or updated kube_cluster resources. When you create the kube_cluster resource, any Kubernetes Service instances you have configured to track that cluster's labels will register that cluster and enable access to it via Teleport.

As a result, you should now see the cluster you registered above when you run tsh kube ls:

tsh kube ls
 Kube Cluster Name Labels                      Selected
 ----------------- --------------------------- --------
 mycluster         teleport.dev/origin=dynamic

The teleport.dev/origin=dynamic label indicates that the cluster was registered dynamically.

You can also log in to the cluster you just registered:

tsh kube login mycluster
Logged into kubernetes cluster "mycluster". Try 'kubectl version' to test the
connection.

List Kubernetes cluster resources

You can list kube_cluster resources with the following command:

tctl get kube_clusters

Update a Kubernetes cluster resource

To update the kube_cluster resource you created earlier, execute the following command to retrieve the resource as it exists on the Auth Service's backend:

tctl get kube_clusters/mycluster > kube_cluster.yaml

Edit the kube_cluster.yaml file to add a label to your kube_cluster:

  kind: kube_cluster
  metadata:
    id: 9999999999999999999
    labels:
      teleport.dev/origin: dynamic
+     env: test
    name: mycluster
  spec:
    aws: {}
    azure: {}
    kubeconfig: KUBECONFIG
  version: v3

Update the resource:

tctl create -f kube_cluster.yaml
kubernetes cluster "mycluster" has been updated

You should now see the updated labels:

tsh kube ls
 Kube Cluster Name Labels                               Selected
 ----------------- ------------------------------------ --------
 mycluster         env=test teleport.dev/origin=dynamic *

Delete Kubernetes cluster resources

To delete the kube_cluster resource you created earlier, run the following command:

tctl rm kube_clusters/mycluster
kubernetes cluster "mycluster" has been deleted

This will unregister the Kubernetes cluster from Teleport:

tsh kube ls
Kube Cluster Name Labels Selected
----------------- ------ --------

Next steps

In this guide, we showed you how to manage kube_cluster resources using tctl. If you are interested in other ways you can manage access to Kubernetes clusters via Teleport, check out the following guides:

• Connect a Kubernetes Cluster to Teleport: How to use the teleport-kube-agent Helm chart to register a Kubernetes cluster with Teleport.
• Kubernetes Access from a Standalone Teleport Cluster: How to use the Teleport Kubernetes Service's configuration file to register a Kubernetes cluster with Teleport.