Kubernetes RBAC permissions - unknown 'clusterrole' flag when attempting to grant permissions? - kubernetes

I am using the Mirantis kubeadm-dind-cluster repository (https://github.com/Mirantis/kubeadm-dind-cluster) as my Kubernetes install; I came across this error when attempting to run a container -
panic: customresourcedefinitions.apiextensions.k8s.io is forbidden: User "system:serviceaccount:default:default" cannot create customresourcedefinitions.apiextensions.k8s.io at the cluster scope
So I attempted to add cluster-admin permissions to my account:
kubectl create clusterrolebinding serviceaccounts-cluster-admin --clusterrole=cluster-admin --group=system:serviceaccounts
And get the following error:
Error: unknown flag: --clusterrole
Why is this? How do I fix this or get around it? I'm not sure how to convert the command into a YAML file to "kubectl create -f" to but it seems like that might be the way to go.
All three nodes are on version 1.8.6.

What version of kubectl are you using? Be sure you are using a version that includes the kubectl create clusterrolebinding command
If your version of kubectl does not support that command, you can try creating it directly via a yaml file (though I'm not sure whether 1.5.x kubectl was happy submitting versions of API objects it didn't know about):
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: serviceaccounts-cluster-admin
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- apiGroup: rbac.authorization.k8s.io
kind: Group
name: system:serviceaccounts

Related

Whats difference between "kubectl auth reconcile" and "kubectl apply" for working with RBAC?

I have some average yaml file defining some average role resource, all yaml should reflect my resource's desired state.
To get new average role into cluster I usually run kubectl apply -f my-new-role.yaml
but now I see this (recommended!?) alternative kubectl auth reconcile -f my-new-role.yaml
Ok, there may be RBAC relationships, ie Bindings, but shouldn't an apply do same thing?
Is there ever a case where one would update (cluster) roles but not want their related (cluster) bindings updated?
The kubectl auth reconcile command-line utility has been added in Kubernetes v1.8.
Properly applying RBAC permissions is a complex task because you need to compute logical covers operations between rule sets.
As you can see in the CHANGELOG-1.8.md:
Added RBAC reconcile commands with kubectl auth reconcile -f FILE. When passed a file which contains RBAC roles, rolebindings, clusterroles, or clusterrolebindings, this command computes covers and adds the missing rules. The logic required to properly apply RBAC permissions is more complicated than a JSON merge because you have to compute logical covers operations between rule sets. This means that we cannot use kubectl apply to update RBAC roles without risking breaking old clients, such as controllers.
The kubectl auth reconcile command will ignore any resources that are not Role, RoleBinding, ClusterRole, and ClusterRoleBinding objects, so you can safely run reconcile on the full set of manifests (see: Use 'kubectl auth reconcile' before 'kubectl apply')
I've created an example to demonstrate how useful the kubectl auth reconcile command is.
I have a simple secret-reader RoleBinding and I want to change a binding's roleRef (I want to change the Role that this binding refers to):
NOTE: A binding to a different role is a fundamentally different binding (see: A binding to a different role is a fundamentally different binding).
# BEFORE
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: secret-admin
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: secret-reader
subjects:
- kind: ServiceAccount
name: service-account-1
namespace: default
# AFTER
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: secret-admin
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: secret-creator
subjects:
- kind: ServiceAccount
name: service-account-1
namespace: default
As we know, roleRef is immutable, so it is not possible to update this secret-admin RoleBinding using kubectl apply:
$ kubectl apply -f secret-admin.yml
The RoleBinding "secret-admin" is invalid: roleRef: Invalid value: rbac.RoleRef{APIGroup:"rbac.authorization.k8s.io", Kind:"Role", Name:"secret-creator"}: cannot change roleRef
Instead, we can use kubectl auth reconcile. If a RoleBinding is updated to a new roleRef, the kubectl auth reconcile command handles a delete/recreate related objects for us.
$ kubectl auth reconcile -f secret-admin.yml
rolebinding.rbac.authorization.k8s.io/secret-admin reconciled
reconciliation required recreate
Additionally, you can use the --remove-extra-permissions and --remove-extra-subjects options.
Finally, we can check if everything has been successfully updated:
$ kubectl describe rolebinding secret-admin
Name: secret-admin
Labels: <none>
Annotations: <none>
Role:
Kind: Role
Name: secret-creator
Subjects:
Kind Name Namespace
---- ---- ---------
ServiceAccount service-account-1 default

Accessing k8s cluster with service account token

Is possible to gain k8s cluster access with serviceaccount token?
My script does not have access to a kubeconfig file, however, it does have access to the service account token at /var/run/secrets/kubernetes.io/serviceaccount/token.
Here are the steps I tried but it is not working.
kubectl config set-credentials sa-user --token=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
kubectl config set-context sa-context --user=sa-user
but when the script ran "kubectl get rolebindings" I get the following error:
Error from server (Forbidden): rolebindings.rbac.authorization.k8s.io is forbidden: User "system:serviceaccount:test:default" cannot list resource "rolebindings" in API group "rbac.authorization.k8s.io" in the namespace "test"
Is possible to gain k8s cluster access with serviceaccount token?
Certainly, that's the point of a ServiceAccount token. The question you appear to be asking is "why does my default ServiceAccount not have all the privileges I want", which is a different problem. One will benefit from reading the fine manual on the topic
If you want the default SA in the test NS to have privileges to read things in its NS, you must create a Role scoped to that NS and then declare the relationship explicitly. SAs do not automatically have those privileges
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
namespace: test
name: test-default
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: whatever-role-you-want
subjects:
- kind: ServiceAccount
name: default
namespace: test
but when the script ran "kubectl get pods" I get the following error: Error from server (Forbidden): rolebindings.rbac.authorization.k8s.io is forbidden: User "system:serviceaccount:test:default" cannot list resource "rolebindings" in API group "rbac.authorization.k8s.io" in the namespace "test"
Presumably you mean you can kubectl get rolebindings, because I would not expect running kubectl get pods to emit that error
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.

Kubernetes OIDC: No valid group mapping

I have the problem that I can log on to my dashboard via OIDC, but then the oidc group information is not mapped correctly and I cannot access the corresponding resources.
Basic setup
K8s version: 1.19.0
K8s setup: 1 master + 2 worker nodes
Based on Debian 10 VMs
CNI: Calico
Louketo Proxy as OIDC proxy
OIDC: Keycloak Server (Keycloak X [Quarkus])
Configurations
I have configured the K8s apiserver with these parameters.
kube-apiserver.yaml
- --oidc-issuer-url=https://test.test.com/auth/realms/Test
- --oidc-client-id=test
- --oidc-username-claim=preferred_username
- --oidc-username-prefix="oidc:"
- --oidc-groups-claim=groups
- --oidc-groups-prefix="oidc:"
ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: "test-cluster-admin"
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- apiGroup: rbac.authorization.k8s.io
kind: Group
name: "Test"
I used the following louketo parameters
Louketo Proxy
/usr/bin/louketo-proxy --discovery-url=$OIDC_DISCOVERY_URL --client-id=$OIDC_CLIENT_ID --client-secret=$OIDC_CLIENT_SECRET -listen=$OIDC_LISTEN_URL --encryption-key=$OIDC_ENCRYPTION_KEY --redirection-url=$OIDC_REDIRECTION_KEY --enable-refresh-tokens=true --upstream-url=$OIDC_UPSTREAM_URL --enable-metrics
I get the following error message inside the dashboard.
K8s error
replicasets.apps is forbidden: User "\"oidc:\"<user_name>" cannot list resource "replicasets" in API group "apps" in the namespace "default"
I hope you can help me with this problem, I already tried most of the manuals from the internet, but haven't found a solution yet.
PS: I have done the corresponding group mapping in the Keycloak server and also validated that the group entry is transferred.
If you are facing the same challenge as I did and you want to integrate Keycloak into your K8s cluster, share the dashboard and connect it to Keycloak, you can find my configuration below. Within my cluster I use the Louketo Proxy as interface between Kubernetes and Keycloak. The corresponding configuration of the deployment is not included in this post.
Keycloak
I want to start with the configuration of Keycloak. In the first step I created a corresponding client with the following settings.
After that I created the two group membership and audience (needed by the louketo proxy) mappers.
The exact settings of the mappers can be taken from the two images.
Group membership mapping
Audience mapping
Kubernetes
In the second step I had to update the api server manifest and create the RoleBinding and ClusterRoleBinding within the Kubernetes cluster.
Api server manifest (default path: /etc/kubernetes/manifests/kube-apiserver.yaml)
- --oidc-issuer-url=https://test.test.com/auth/realms/Test
- --oidc-client-id=test
- --oidc-username-claim=preferred_username
- --oidc-username-prefix="oidc:"
- --oidc-groups-claim=groups
- --oidc-groups-prefix="oidc:"
RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: "test"
namespace: "kubernetes-dashboard"
subjects:
- kind: User
name: "\"oidc:\"Test"
namespace: "kube-system"
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: "test"
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- apiGroup: rbac.authorization.k8s.io
kind: Group
name: "\"oidc:\"Test"
#Community I hope I can help you with this configuration. If you have any questions, feel free to ask me.
This is a community wiki answer aimed to approach the issue from the Kubernetes side. Any one familiar with the possible Keycloak group/role mapping solution feel free to edit it.
The error you see means that the service account for OIDC doesn't have the proper privileges to list replicasets in the default namespace. The easiest way out of it would be to simply setup the ServiceAccount, ClusterRole and ClusterRoleBinding from scratch and make sure it has the proper privileges. For example, you can create a clusterrolebinding with permissions “admin” by executing:
kubectl create clusterrolebinding OIDCrolebinding - -clusterrole=admin - - group=system:serviceaccounts:OIDC
The same can be done for the ClusterRole:
kubectl create clusterrole OIDC --verb=get,list,watch --resource=replicasets --namespace=default
More examples of how to use the kubectl create in this scenario can be found here.
Here you can find a whole official guide regarding the RBAC Authorization.
EDIT:
Also, please also check if your ClusterRoleBinding for the "\"oidc:\"<user_name>" is in the "default" namespace.

Cannot list resource "configmaps" in API group when deploying Weaviate k8s setup on GCP

When running (on GCP):
$ helm upgrade \
--values ./values.yaml \
--install \
--namespace "weaviate" \
"weaviate" \
weaviate.tgz
It returns;
UPGRADE FAILED
Error: configmaps is forbidden: User "system:serviceaccount:kube-system:default" cannot list resource "configmaps" in API group "" in the namespace "ku
be-system"
Error: UPGRADE FAILED: configmaps is forbidden: User "system:serviceaccount:kube-system:default" cannot list resource "configmaps" in API group "" in t
he namespace "kube-system"
UPDATE: based on solution
$ vim rbac-config.yaml
Add to the file:
apiVersion: v1
kind: ServiceAccount
metadata:
name: tiller
namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: tiller
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: cluster-admin
subjects:
- kind: ServiceAccount
name: tiller
namespace: kube-system
Run:
$ kubectl create -f rbac-config.yaml
$ helm init --service-account tiller --upgrade
Note: based on Helm v2.
tl;dr: Setup Helm with the appropriate authorization settings for your cluster, see https://v2.helm.sh/docs/using_helm/#role-based-access-control
Long Answer
Your experience is not specific to the Weaviate Helm chart, rather it looks like Helm is not setup according to the cluster authorization settings. Other Helm commands should fail with the same or a similar error.
The following error
Error: configmaps is forbidden: User "system:serviceaccount:kube-system:default" cannot list resource "configmaps" in API group "" in the namespace "ku
be-system"
means that the default service account in the kube-system namespace is lacking permissions. I assume you have installed Helm/Tiller in the kube-system namespace as this is the default if no other arguments are specified on helm init. Since you haven't created a specific Service Account for Tiller to use it defaults to the default service account.
Since you are mentioning that you are running on GCP, I assume this means you are using GKE. GKE by default has RBAC Authorization enabled. In an RBAC setting no one has any rights by default, all rights need to be explicitly granted.
The helm docs list several options on how to make Helm/Tiller work in an RBAC-enabled setting. If the cluster has the sole purpose of running Weaviate you can choose the simplest option: Service Account with cluster-admin role. The process described there essentially creates a dedicated service account for Tiller, and adds the required ClusterRoleBinding to the existing cluster-admin ClusterRole. Note that this effectively makes Helm/Tiller an admin of the entire cluster.
If you are running a multi-tenant cluster and/or want to limit Tillers permissions to a specific namespace, you need to choose one of the alternatives.

Kubernetes log, User "system:serviceaccount:default:default" cannot get services in the namespace

Forbidden!Configured service account doesn't have access. Service account may have been revoked. User "system:serviceaccount:default:default" cannot get services in the namespace "mycomp-services-process"
For the above issue I have created "mycomp-service-process" namespace and checked the issue.
But it shows again message like this:
Message: Forbidden!Configured service account doesn't have access. Service account may have been revoked. User "system:serviceaccount:mycomp-services-process:default" cannot get services in the namespace "mycomp-services-process"
Creating a namespace won't, of course, solve the issue, as that is not the problem at all.
In the first error the issue is that serviceaccount default in default namespace can not get services because it does not have access to list/get services. So what you need to do is assign a role to that user using clusterrolebinding.
Following the set of minimum privileges, you can first create a role which has access to list services:
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
namespace: default
name: service-reader
rules:
- apiGroups: [""] # "" indicates the core API group
resources: ["services"]
verbs: ["get", "watch", "list"]
What above snippet does is create a clusterrole which can list, get and watch services. (You will have to create a yaml file and apply above specs)
Now we can use this clusterrole to create a clusterrolebinding:
kubectl create clusterrolebinding service-reader-pod \
--clusterrole=service-reader \
--serviceaccount=default:default
In above command the service-reader-pod is name of clusterrolebinding and it is assigning the service-reader clusterrole to default serviceaccount in default namespace. Similar steps can be followed for the second error you are facing.
In this case I created clusterrole and clusterrolebinding but you might want to create a role and rolebinding instead. You can check the documentation in detail here
This is only for non prod clusters
You should bind service account system:serviceaccount:default:default (which is the default account bound to Pod) with role cluster-admin, just create a yaml (named like fabric8-rbac.yaml) with following contents:
# NOTE: The service account `default:default` already exists in k8s cluster.
# You can create a new account following like this:
#---
#apiVersion: v1
#kind: ServiceAccount
#metadata:
# name: <new-account-name>
# namespace: <namespace>
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: fabric8-rbac
subjects:
- kind: ServiceAccount
# Reference to upper's `metadata.name`
name: default
# Reference to upper's `metadata.namespace`
namespace: default
roleRef:
kind: ClusterRole
name: cluster-admin
apiGroup: rbac.authorization.k8s.io
Then, apply it by running kubectl apply -f fabric8-rbac.yaml.
If you want unbind them, just run kubectl delete -f fabric8-rbac.yaml.
Just to add.
This can also occur when you are redeploying an existing application to the wrong Kubernetes cluster that are similar.
Ensure you check to be sure that the Kubernetes cluster you're deploying to is the correct cluster.