Kubernetes RBAC
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Assigning namespaces permissions to default service account in namepsace test.
Create namespace
kubectl create namespace test
Look at info
- We will be using cluster-admin role for our binding.
- Notice difference. With admin you will have to assign resources with cluster binding it will have access to entire namespace.
- https://stackoverflow.com/questions/60287556/difference-between-cluster-admin-and-admin-kubernetes-clusterroles
kubectl get clusterroles -n default cluster-admin -oyaml kubectl get clusterroles -n default admin -oyaml
View secrets for sa and get secrets
kubectl -n test get sa
kubectl -n test get secret
kubectl get secrets default-token-9v6lb -o jsonpath='{.data.token}' | base64 --decode # Paste to token in .kube/config file
Create RoleBinding using clusterrole cluster-admin
kubectl create rolebinding test-sa-default --clusterrole=cluster-admin --serviceaccount=test:default
On our service account shell using kubectl update .kube/config
~/.kube/config
...
users:
- name: admin
user:
token: <token we got from test:default service account above>
Test access on remote service account shell
kubectl get pods -n test kubectl get pods -n default kubectl get sa -n test kubectl auth can-i get pods kubectl auth can-i delete deployments
Delete clusterrolebinding and see that you lose access
kubectl delete clusterrolebinding test-sa-default kubectl get pods -n test
######## NOTES
https://jeremievallee.com/2018/05/28/kubernetes-rbac-namespace-user.html
One way
https://devopscube.com/kubernetes-api-access-service-account/
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
name: api-service-account
namespace: devops-tools
EOF
cat <<EOF | kubectl apply -f -
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: api-cluster-role
namespace: devops-tools
rules:
- apiGroups:
- ""
- apps
- autoscaling
- batch
- extensions
- policy
- rbac.authorization.k8s.io
resources:
- pods
- componentstatuses
- configmaps
- daemonsets
- deployments
- events
- endpoints
- horizontalpodautoscalers
- ingress
- jobs
- limitranges
- namespaces
- nodes
- pods
- persistentvolumes
- persistentvolumeclaims
- resourcequotas
- replicasets
- replicationcontrollers
- serviceaccounts
- services
verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]
EOF
kubectl api-resources
cat <<EOF | kubectl apply -f -
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: api-cluster-role-binding
subjects:
- namespace: devops-tools
kind: ServiceAccount
name: api-service-account
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: api-cluster-role
EOF
kubectl auth can-i get pods --as=system:serviceaccount:devops-tools:api-service-account
kubectl auth can-i delete deployments --as=system:serviceaccount:devops-tools:api-service-account
kubectl get serviceaccount api-service-account -o=jsonpath='{.secrets[0].name}' -n devops-tools
kubectl get secrets <service-account-token-name> -o=jsonpath='{.data.token}' -n devops-tools | base64 -D
kubectl get endpoints | grep kubernetes
curl -k https://35.226.193.217/api/v1/namespaces -H "Authorization: Bearer <token>"
Way Number
1️⃣ Create Namespace
kubectl create namespace mynamespace
2️⃣ Create Service Account with permissions
Open a new file. Let’s call it access.yaml. We’re going to create the user (service account), a role, and attach that role to that user.
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: mynamespace-user
namespace: mynamespace
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: mynamespace-user-full-access
namespace: mynamespace
rules:
- apiGroups: ["", "extensions", "apps"]
resources: ["*"]
verbs: ["*"]
- apiGroups: ["batch"]
resources:
- jobs
- cronjobs
verbs: ["*"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: mynamespace-user-view
namespace: mynamespace
subjects:
- kind: ServiceAccount
name: mynamespace-user
namespace: mynamespace
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: mynamespace-user-full-access
As you can see, in the Role definition, we add full access to everything in that namespace, including batch types like jobs or cronjobs. As it is a Role, and not a ClusterRole, it is going to be applied to a single namespace: mynamespace. For more details about roles in Kubernetes, check out the official documentation.
Now, let’s create all of this:
kubectl create -f access.yaml
You should see the three components being created.
3️⃣ Get Secrets
The first thing we need to do now is to get the name of the service account’s secret. Run the following command and copy the name of the secret.
kubectl describe sa mynamespace-user -n mynamespace
For this tutorial, let’s say that the secret is named mynamespace-user-token-xxxxx.
We now need to get the service account’s Token and the Certificate Authority. For this, we are going to read them using kubectl. Now, as Kubernetes secrets are base64 encoded, we’ll also need to decode them.
Here’s how you get the User Token:
kubectl get secret mynamespace-user-token-xxxxx -n mynamespace -o "jsonpath={.data.token}" | base64 -D
And here’s how you get the Certificate:
kubectl get secret mynamespace-user-token-xxxxx -n mynamespace -o "jsonpath={.data['ca\.crt']}"
4️⃣ Create Kube config
We now have everything we need. The only thing remaining is creating the Kube config file, with the data we previously gathered:
apiVersion: v1
kind: Config
preferences: {}
# Define the cluster
clusters:
- cluster:
certificate-authority-data: PLACE CERTIFICATE HERE
# You'll need the API endpoint of your Cluster here:
server: https://YOUR_KUBERNETES_API_ENDPOINT
name: my-cluster
# Define the user
users:
- name: mynamespace-user
user:
as-user-extra: {}
client-key-data: PLACE CERTIFICATE HERE
token: PLACE USER TOKEN HERE
# Define the context: linking a user to a cluster
contexts:
- context:
cluster: my-cluster
namespace: mynamespace
user: mynamespace-user
name: mynamespace
# Define current context
current-context: mynamespace
Way Number 2
https://stackoverflow.com/questions/66296470/accessing-k8s-cluster-with-service-account-token
1
Yes, it is possible. For instance, if you login K8S dashboard via token it does use the same way.
Follow these steps;
Create a service account
$ kubectl -n <your-namespace-optional> create serviceaccount <service-account-name>
A role binding grants the permissions defined in a role to a user or set of users. You can use a predefined role or you can create your own. Check this link for more info. https://kubernetes.io/docs/reference/access-authn-authz/rbac/#rolebinding-example
$ kubectl create clusterrolebinding <binding-name> --clusterrole=cluster-admin --serviceaccount=<namespace>:<service-account-name>
Get the token name
$ TOKENNAME=`kubectl -n <namespace> get serviceaccount/<service-account-name> -o jsonpath='{.secrets[0].name}'`
Finally, get the token and set the credentials
$ kubectl -n <namespace> get secret $TOKENNAME -o jsonpath='{.data.token}'| base64 --decode
$ kubectl config set-credentials <service-account-name> --token=<output from previous command>
$ kubectl config set-context --current --user=<service-account-name>
If you follow these steps carefully your problem will be solved.
https://discuss.kubernetes.io/t/how-to-create-user-in-kubernetes-cluster-and-give-it-access/9101
https://kubernetes.io/docs/reference/access-authn-authz/authentication/
https://jeremievallee.com/2018/05/28/kubernetes-rbac-namespace-user.html
https://jeremievallee.com/2018/05/28/kubernetes-rbac-namespace-user.html
After going through all the above mentioned block, I found below solution Create user CSR openssl genrsa -out user1.key 2048 openssl req -new -key user1.key -out user1.csr Approve CSR openssl x509 -req -in user1.csr -CA /etc/kubernetes/pki/ca.crt -CAkey /etc/kubernetes/pki/ca.key -CAcreateserial -out user1.crt -days 500 Create Role or ClusterRole cat role.yml kind: Role apiVersion: rbac.authorization.k8s.io/v1beta1 4 metadata: namespace: test-namespace name: user1-role rules: - apiGroups: ["", “extensions”, “apps”] resources: [“deployments”, “pods”, “services”] verbs: [“get”, “list”, “watch”, “create”, “update”, “patch”, “delete”] Create RoleBindings cat binding.yml kind: RoleBinding apiVersion: rbac.authorization.k8s.io/v1beta1 4 metadata: name: user1-rolebinding namespace: test-namespace subjects: kind: User name: user1 apiGroup: “” roleRef: kind: Role name: user1-role apiGroup: “” Use it kubectl config set-credentials user1 --client-certificate=/root/user1.crt --client-key=user1.key kubectl config set-context user1-context --cluster=kubernetes --namespace=test-namespace --user=user1