Create user in Kubernetes for kubectl - json

Question

I need to create users to assign them permissions with RBAC, I create them as follows:
echo -n "lucia" | base64
bHVjaWE=
echo -n "pass" | base64
cGFzcw==
apiVersion: v1
kind: Secret
metadata:
name: lucia-secret
type: Opaque
data:
username: bHVjaWE=
password: cGFzcw==
Or create with:
kubectl create secret generic lucia-secret --from-literal=username='lucia',password='pass'
I don't know how to continue
USER_NICK=lucia
kubectl config set-credentials $USER_NICK \
--username=lucia \
--password=pass
kubectl get secret lucia-secret -o json | jq -r '.data["ca.crt"]' | base64 -d > ca.crt
endpoint=`kubectl config view -o jsonpath="{.clusters[?(#.name == \"$name\")].cluster.server}"`
kubectl config set-cluster cluster-for-lucia \
--embed-certs=true \
--server=$endpoint \
--certificate-authority=./ca.crt
kubectl config set-context context-lucia \
--cluster=cluster-for-lucia \
--user=$USER_NICK \
--namespace=default
ca.crt is null
Thank you for your help!

Answer 1

As kubernetes docs and Articles uses certificate to create or authenticate users for kubectl client. However there is one easy way to do it by using ServiceAccount. One can use ServiceAccount as a group to provide RBAC control authentication and it is very easy and descriptive. Here are the steps.
All the steps i am executing is in default namespace. I am going to create a pod readonly user which can get,list,watch any pod in all namespaces.
Create a ServiceAccount, say 'readonlyuser'.
kubectl create serviceaccount readonlyuser
Create cluster role, say 'readonlyuser'.
kubectl create clusterrole readonlyuser --verb=get --verb=list --verb=watch --resource=pods
Create cluster role binding, say 'readonlyuser'.
kubectl create clusterrolebinding readonlyuser --serviceaccount=default:readonlyuser --clusterrole=readonlyuser
Now get the token from secret of ServiceAccount we have created before. we will use this token to authenticate user.
TOKEN=$(kubectl describe secrets "$(kubectl describe serviceaccount readonlyuser | grep -i Tokens | awk '{print $2}')" | grep token: | awk '{print $2}')
Now set the credentials for the user in kube config file. I am using 'vikash' as username.
kubectl config set-credentials vikash --token=$TOKEN
Now Create a Context say podreader. I am using my clustername 'kubernetes' here.
kubectl config set-context podreader --cluster=kubernetes --user=vikash
Finally use the context .
kubectl config use-context podreader
And that's it. Now one can execute kubectl get pods --all-namespaces. One can also check the access by executing as given:
~ : $ kubectl auth can-i get pods --all-namespaces
yes
~ : $ kubectl auth can-i create pods
no
~ : $ kubectl auth can-i delete pods
no

Answer 2

In this guide you can find how to configure a user for your cluster: https://docs.bitnami.com/kubernetes/how-to/configure-rbac-in-your-kubernetes-cluster/#use-case-1-create-user-with-limited-namespace-access
Long story short:
Create certificates for the user
Create a certificate sign request
Sign the certificate with the cluster certificate authority
Create a configuration for your user
Add RBAC rules for this user or its group
Regarding the ca.crt, you need to find it in your master host.
Edited: In the case of GKE, check here https://cloud.google.com/container-engine/docs/iam-integration

Answer 3

A little late update for what worked for me.
I needed also to filter out by namespaces, to give developers read-only access to main app resources, but not nodes, secrets, ingress-controllers, ingress or other namespaces.
Modify and apply the follwing YAML:
apiVersion: v1
kind: ServiceAccount
metadata:
name: sa-reader
namespace: default
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: reader-cr
rules:
- verbs: ["get", "list", "watch"]
resources:
- namespaces
- services
- endpoints
- pods
- deployments
- configmaps
- jobs
- cronjobs
- daemonsets
- statefulsets
- replicasets
- persistentvolumes
apiGroups: ["","apps","batch"]
- verbs: ["create", "delete"]
resources: ["pods"]
apiGroups: [""]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: read-tuxerrante-pods-rb
namespace: tuxerrante
subjects:
- kind: ServiceAccount
name: sa-reader
namespace: default
roleRef:
kind: ClusterRole
name: reader-cr
apiGroup: rbac.authorization.k8s.io
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: read-tuxerrante-round-pods-rb
namespace: tuxerrante-round
subjects:
- kind: ServiceAccount
name: sa-reader
namespace: default
roleRef:
kind: ClusterRole
name: reader-cr
apiGroup: rbac.authorization.k8s.io
# THIS WILL APPEND CONFIGURATIONS TO YOUR CURRENT KUBECONFIG
$ TOKEN=$(kubectl describe -n default secrets "$(kubectl describe -n default serviceaccount sa-reader | grep -i Tokens | awk '{print $2}')" | grep token: | awk '{print $2}')
$ kubectl config set-credentials reader-user --token=$TOKEN
$ kubectl config set-context cluster-reader --cluster=cluster-svil --user=reader-user
# I PREFER TO COPY THE PREVIOUS NEW CONFIG IN A NEW FILE AND THEN USE IT
#
$ export KUBECONFIG=~/.kube/tuxerrante-reader.kubeconfig
$ kubectl config use-context cluster-reader
$ kubectl auth can-i get pods --all-namespaces
$ kubectl auth can-i create pods
$ kubectl auth can-i delete pods
$ kubectl -n tuxerrante get pods