Dedicated K8s ServiceAccounts

Prerequisites

  • Akeyless Gateway with network access to the Kubernetes (K8s) cluster.

  • K8s v1.21 and higher.

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Info

Required Gateway Access Permissions

To set K8s Authentication method, make sure you have Access Permissions on your Gateway to manage the K8s Auth.

Dedicated ServiceAccount

This flow describes the creation of a dedicated K8s ServiceAccount which will work based on token projection.

For a Rancher cluster, please create your Rancher API Key and refer to Extract K8s Cluster CA Certificate to extract your Rancher server CA certificate.

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Note

To enable and use token request projection on a self-managed cluster, you must specify each of the following command line arguments to kube-apiserver:
--service-account-issuer
--service-account-key-file
--service-account-signing-key-file
--api-audiences

For more details, check out the minikube configuration example at the end of this page.

  1. Create a ServiceAccount named gateway-token-reviewer with permission to access token review API. This ServiceAccount will be used to validate a K8s JWT coming from a pod that will try to authenticate to Akeyless.
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gateway-token-reviewer
  namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: role-tokenreview-binding
  namespace: default
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:auth-delegator
subjects:
- kind: ServiceAccount
  name: gateway-token-reviewer
  namespace: default

Apply:

kubectl apply -f akl_gw_token_reviewer.yaml

Bearer Token Extraction for K8s Server v1.23 or lower

  1. Extract the gateway-token-reviewer ServiceAccount secret name:
GW_SA_NAME=$(kubectl get sa gateway-token-reviewer \
    --output jsonpath="{.secrets[*]['name']}")
  1. Extract the ServiceAccount JWT Bearer Token (K8s Server <= v1.23):
SA_JWT_TOKEN=$(kubectl get secret $GW_SA_NAME \
    --output 'go-template={{ .data.token | base64decode }}')

Bearer Token Extraction for K8s Server v1.24 or higher

K8s won’t generate Secrets automatically for ServiceAccounts, to get your ServiceAccount token, run the following commands instead:

  1. Create the long-lived ServiceAccount secret called gateway-token-reviewer-token (K8s Server >= v1.24):
apiVersion: v1
kind: Secret
metadata:
  name: gateway-token-reviewer-token
  namespace: default
  annotations:
    kubernetes.io/service-account.name: gateway-token-reviewer
type: kubernetes.io/service-account-token
kubectl apply -f akl_gw_token_reviewer_token.yaml
  1. Extract the ServiceAccount JWT Bearer Token (K8s Server >= v1.24):
SA_JWT_TOKEN=$(kubectl get secret gateway-token-reviewer-token \
  --output 'go-template={{.data.token | base64decode}}')

Extract K8s Cluster CA Certificate

To extract the K8s cluster CA cert used to talk to K8s API run the following command:

CA_CERT=$(kubectl config view --raw --minify --flatten  \
    --output 'jsonpath={.clusters[].cluster.certificate-authority-data}')
CA_CERT=$(openssl s_client -host <Rancher Server> -port 443 2>&1  | sed -n -e '/-----BEGIN CERTIFICATE-----/,/-----END CERTIFICATE-----/ p' | base64)

Create K8s Auth Method

  1. Use the Akeyless CLI to create the K8s auth method which will restrict access to two different pods, named mypod1 and mypod2 from the namespace my-namespace-a. The result contains an access Id and a private key that you will need later for the K8S Auth configuration in your Akeyless Gateway:
akeyless create-auth-method-k8s -n my-k8s-auth-method --bound-pod-names mypod1 \
    --bound-pod-names mypod2 --bound-namespaces my-namespace-a --json

Upon successful creation, the response:

{
  "access_id": "p-abcdefg1234",
  "prv_key": "LS0tLS1CRUdJTiBSUlNDUUxt.....QVRFIEtFWS0tLS0tCg=="
}

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Note

Save returned private key & AccessID for next steps inside an environment variables $PRV_KEY and $ACCESS_ID.

Create K8s Gateway Auth Config Using Bearer Tokens

To discover your K8s service account issuer run the following command:

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Note

The K8s Issuer parameter is no longer used by default, as the issuer validation is done by the API server, if you still wish to work with local issuer validation open a new tab to run this command as it starts a server. Then, go back to your original tab to extract the issuer.

Forwarding the K8s API:

kubectl proxy --api-prefix=/k8s-api

Extract the issuer:

K8S_ISSUER=$(curl -s http://localhost:8001/k8s-api/.well-known/openid-configuration | jq -r .issuer)

Or extract the issuer directly from your pod token:

K8S_ISSUER=$(jq -R 'split(".") | .[1] | @base64d | fromjson |.iss' <<< $(cat /var/run/secrets/kubernetes.io/serviceaccount/token) -r)

Use the Akeyless CLI to create the K8S auth config:

akeyless gateway-create-k8s-auth-config --name k8s-conf \
--gateway-url https://<Your_Akeyless_GW_URL:8000> \
--access-id $ACCESS_ID \
--signing-key $PRV_KEY \
--k8s-host https://<Your_K8s_Cluster_IP:8443> \
--token-reviewer-jwt $SA_JWT_TOKEN \
--k8s-ca-cert $CA_CERT \
--k8s-issuer $K8S_ISSUER
akeyless gateway-create-k8s-auth-config --name k8s-conf-rancher \
--gateway-url https://<Your_Akeyless_GW_URL:8000> \
--access-id $ACCESS_ID \
--signing-key $PRV_KEY \
--cluster-api-type rancher \
--k8s-host https://<Rancher Host:443> \
--k8s-ca-cert $CA_CERT \
--k8s-issuer $K8S_ISSUER \
--rancher-api-key <API_KEY> \
--rancher-cluster-id <CLUSTER_ID> \

Where:

  • name: The config name (will be used during the authentication process).

  • gateway-url: Akeyless Gateway Configuration Manager URL (port 8000).

  • access-id: The Access Id of the K8s auth method that was created.

  • signing-key: The private key (base64 encoded) associated with the public key defined in the K8s auth
    (The private key that was created when the K8s auth method was created previously).

  • k8s-host: The URL of your K8s API server or your Rancher server.

  • token-reviewer-jwt: The ServiceAccount JWT used to access the TokenReview API
    (relevant only to native_k8s access type).

  • k8s-ca-cert: The certificate to use to validate the K8s cluster.

  • k8s-issuer: Optional, the Kubernetes JWT issuer name (default is kubernetes/serviceaccount).

When the cluster access type is Rancher, add the following parameters:
(in addition to the relevant parameters above)

  • cluster-api-type: Cluster access type, we will write rancher (default is native_k8s).
  • rancher-api-key: Rancher Bearer token, based on the created Rancher API Key..
  • rancher-cluster-id: Rancher Cluster ID, i.e., your Rancher API Key Scope.

Authenticate from a pod in your K8s cluster

  1. Create a namespace with a name that the auth method access is restricted to:
kubectl create namespace my-namespace-a
  1. In this namespace, create a pod with a name that the auth method access is restricted to:
kubectl run mypod1 --image=nginx -n my-namespace-a
  1. Start an interactive shell session on the pod and perform the following commands in the pod :
kubectl exec --stdin=true --namespace my-namespace-a  --tty=true mypod1 -- /bin/sh
  1. Install Akeyless CLI inside your pod:
curl -o akeyless https://akeyless-cli.s3.us-east-2.amazonaws.com/cli/latest/production/cli-linux-amd64
chmod +x akeyless
  1. Authenticate via your Kubernetes auth method with the following parameters:
./akeyless auth --access-id $ACCESS_ID \
    --access-type k8s \
    --gateway-url https://<Your_Akeyless_GW_URL:8000> \
    --k8s-auth-config-name k8s-conf

Where:

  • access-id: The Access Id of the K8s auth method that was created previously.

  • access-type: The Auth Method access type, k8s.

  • gateway-url: Akeyless Gateway Configuration Manager URL (port 8000).

  • k8s-auth-config-name: The K8s auth config name in your Gateway.

Upon successful authentication, the response will be:

Authentication succeeded.
Token: t-bb7b...3564a7c9

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Note

Delete the private key and Access ID which you stored as an environment variables $PRV_KEY and $ACCESS_ID

Available claims for K8s Auth

The following list of claims can be configured within Akeyless Role-based Access Control (RBAC) to control and segregate the relevant policy for K8s.

"service_account_name"
"service_account_uid"
"service_account_secret_name"
"namespace"
"aud"
"pod_name"  # available only when "token request projection" is enabled on your Kubernetes cluster
"pod_uid"   # available only when "token request projection" is enabled on your Kubernetes cluster

Each claim can be enforced as part of your role association to enforce the right policy for your items.

Enable token request projection on Minikube

To enable token request projection on a managed K8s cluster you can follow this guide.

To get this to work with Minikube you can start your cluster with the following configuration.

minikube start \
    --vm-driver=none \
    --extra-config=apiserver.service-account-signing-key-file=/var/lib/minikube/certs/sa.key \
    --extra-config=apiserver.service-account-key-file=/var/lib/minikube/certs/sa.pub \
    --extra-config=apiserver.service-account-issuer=api \
    --extra-config=apiserver.service-account-api-audiences=api,spire-server \
    --extra-config=apiserver.authorization-mode=Node,RBAC \
    --extra-config=kubelet.authentication-token-webhook=true

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Note

This example uses api as the service account issuer name, for your service accounts API audience.

Tutorial

Check out our tutorial video on Kubernetes Authentication.