project-azorian / k8s-oidc-helper

Helper tool for authenticating to Kubernetes using Google's OpenID Connect

k8s-oidc-helper

This is a small helper tool to get a user get authenticated with Kubernetes OIDC using Google as the Identity Provider.

Given a ClientID and ClientSecret, the tool will output the necessary configuration for kubectl that you can add to ~/.kube/config

$ k8s-oidc-helper -c ./client_secret.json
Enter the code Google gave you: <code>

# Add the following to your ~/.kube/config
users:
- name: [email protected]
  user:
    auth-provider:
      config:
        client-id: <client-id>
        client-secret: <client-secret>
        id-token: <id-token>
        idp-issuer-url: https://accounts.google.com
        refresh-token: <refresh-token>
      name: oidc

To merge the new configuration into your existing kubectl config file, run:

$ k8s-oidc-helper -c ./client_secret.json --write
Enter the code Google gave you: <code>

Configuration has been written to ~/.kube/config

# Then you can associate that user to a cluster
$ kubectl config set-context <context-name> --cluster <cluster-name> --user <[email protected]>
$ kubectl config use-context <context-name>

Setup

There is a bit of setup involved before you can use this tool.

First, you'll need to create a project and OAuth 2.0 Credential in the Google Cloud Console. You can follow this guide on creating an application, but do NOT create a web application. You'll need to select "Other" as the Application Type. Once that is created, you can download the ClientID and ClientSecret as a JSON file for ease of use.

Second, your kube-apiserver will need the following flags on to use OpenID Connect.

--oidc-issuer-url=https://accounts.google.com \
--oidc-username-claim=email \
--oidc-client-id=<Your client ID>\

Role-Based Access Control

If you are using RBAC as your --authorization-mode, you can use the following ClusterRole and ClusterRoleBinding for administrators that need cluster-wide access.

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1alpha1
metadata:
  name: admin-role
rules:
- apiGroups: ["*"]
  resources: ["*"]
  verbs: ["*"]
  nonResourceURLs: ["*"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1alpha1
metadata:
  name: admin-binding
subjects:
- kind: User
  name: [email protected]
roleRef:
  kind: ClusterRole
  name: admin-role

Installation

go get github.com/micahhausler/k8s-oidc-helper

Usage

Usage of k8s-oidc-helper:
      --client-id string       The ClientID for the application
      --client-secret string   The ClientSecret for the application
  -c, --config string          Path to a json file containing your application's ClientID and ClientSecret. Supercedes the --client-id and --client-secret flags.
      --file ~/.kube/config    The file to write to. If not specified, ~/.kube/config is used
  -o, --open                   Open the oauth approval URL in the browser (default true)
  -v, --version                Print version and exit
  -w, --write                  Write config to file. Merges in the specified file

License

MIT License. See License for full text