authentik on Kubernetes

authentik¹ is an open-source Identity Provider, focused on flexibility and versatility. With authentik, site administrators, application developers, and security engineers have a dependable and secure solution for authentication in almost any type of environment.

There are robust recovery actions available for the users and applications, including user profile and password management. You can quickly edit, deactivate, or even impersonate a user profile, and set a new password for new users or reset an existing password.

You can use authentik in an existing environment to add support for new protocols, so introducing authentik to your current tech stack doesn't present re-architecting challenges. We already support all of the major providers, such as OAuth2, SAML, LDAP , and SCIM, so you can pick the protocol that you need for each application.

See a comparison with other IDPs here.

authentik requirements

Preparation

authentik Namespace

We need a namespace to deploy our HelmRelease and associated YAMLs into. Per the flux design, I create this example yaml in my flux repo at /bootstrap/namespaces/namespace-authentik.yaml:

apiVersion: v1
kind: Namespace
metadata:
  name: authentik

authentik HelmRepository

We're going to install the authentik helm chart from the authentik repository, so I create the following in my flux repo (assuming it doesn't already exist):

apiVersion: source.toolkit.fluxcd.io/v1beta1
kind: HelmRepository
metadata:
  name: authentik
  namespace: flux-system
spec:
  interval: 15m
  url: https://charts.goauthentik.io/

authentik Kustomization

Now that the "global" elements of this deployment (just the HelmRepository in this case) have been defined, we do some "flux-ception", and go one layer deeper, adding another Kustomization, telling flux to deploy any YAMLs found in the repo at /authentik/. I create this example Kustomization in my flux repo:

apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
kind: Kustomization
metadata:
  name: authentik
  namespace: flux-system
spec:
  interval: 30m
  path: ./authentik
  prune: true # remove any elements later removed from the above path
  timeout: 10m # if not set, this defaults to interval duration, which is 1h
  sourceRef:
    kind: GitRepository
    name: flux-system
  healthChecks:
    - apiVersion: helm.toolkit.fluxcd.io/v2beta1
      kind: HelmRelease
      name: authentik
      namespace: authentik

authentik DNSEndpoint

If, like me, you prefer to create your DNS records the "GitOps way" using ExternalDNS, create something like the following example to create a DNS entry for your Authentik ingress:

apiVersion: externaldns.k8s.io/v1alpha1
kind: DNSEndpoint
metadata:
  name: "authentik.example.com"
  namespace: authentik
spec:
  endpoints:
  - dnsName: "authentik.example.com"
    recordTTL: 180
    recordType: CNAME
    targets:
    - "traefik-ingress.example.com"  

authentik HelmRelease

Lastly, having set the scene above, we define the HelmRelease which will actually deploy authentik into the cluster. We start with a basic HelmRelease YAML, like this example:

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: authentik
  namespace: authentik
spec:
  chart:
    spec:
      chart: authentik
      version: 2023.10.x # auto-update to semver bugfixes only 
      sourceRef:
        kind: HelmRepository
        name: authentik
        namespace: flux-system
  interval: 15m
  timeout: 5m
  releaseName: authentik
  values: # paste contents of upstream values.yaml below, indented 4 spaces 

If we deploy this helmrelease as-is, we'll inherit every default from the upstream authentik helm chart. That's probably hardly ever what we want to do, so my preference is to take the entire contents of the authentik helm chart's values.yaml, and to paste these (indented), under the values key. This means that I can then make my own changes in the context of the entire values.yaml, rather than cherry-picking just the items I want to change, to make future chart upgrades simpler.

Then work your way through the values you pasted, and change any which are specific to your configuration.

Configure authentik Helm Chart

The following sections detail suggested changes to the values pasted into /authentik/helmrelease-authentik.yaml from the authentik helm chart's values.yaml. The values are already indented correctly to be copied, pasted into the HelmRelease, and adjusted as necessary.

Set authentik secret key

Authentik needs a secret key for signing cookies (not singing for cookies! ), so set it below, and don't change it later (or feed it after midnight!):

    authentik:
      # -- Log level for server and worker
      log_level: info
      # -- Secret key used for cookie singing and unique user IDs,
      # don't change this after the first install
      secret_key: "ilovesingingcookies"

Set bootstrap credentials

By default, when you install the authentik helm chart, you'll get to set your admin user's (akadmin) when you first login. You can pre-configure this password by setting the AUTHENTIK_BOOTSTRAP_PASSWORD env var as illustrated below.

If you're after a more hands-off implementation, you can also pre-set a "bootstrap token", which can be used to interact with the authentik API programatically (see example below):

    env:
      AUTHENTIK_BOOTSTRAP_PASSWORD: "iamusedbyhumanz"
      AUTHENTIK_BOOTSTRAP_TOKEN: "iamusedbymachinez"

Configure Redis for authentik

authentik uses Redis as the broker for Celery background tasks. The authentik helm chart defaults to provisioning an 8Gi PVC for redis, which seems like overkill for a simple broker. You can tweak the size of the Redis PVC by setting:

    redis:
      master:
        persistence:
          size: 1Gi

Configure PostgreSQL for authentik

Although technically you can leave the PostgreSQL password blank, authentik-server will just error with an error like fe_sendauth: no password supplied, so ensure you set the password, both in authentik.postgresql.password and in postgresql.postgresqlPassword:

At the very least, you'll want to set the following

    authentik:
      postgresql:
        password: "Iamaverysecretpassword"

    postgresql:
      postgresqlPassword: "Iamaverysecretpassword"

As with Redis above, you may feel (like I do) that provisioning an 8Gi PVC for a database containing 1 user and a handful of app configs is overkill. You can adjust the size of the PostgreSQL PVC by setting:

    postgresql:
      persistence:
        size: 1Gi 

Ingress

Setup your ingress for the authentik UI. If you plan to add outposts to proxy other un-authenticated endpoints later, this is where you'll add them:

    ingress:
      enabled: true
      ingressClassName: "nginx" 
      annotations: {}
      labels: {}
      hosts:
        - host: authentik.example.com
          paths:
            - path: "/"
              pathType: Prefix
      tls: []

Install authentik!

Commit the changes to your flux repository, and either wait for the reconciliation interval, or force a reconcilliation using flux reconcile source git flux-system. You should see the kustomization appear...

~ ❯ flux get kustomizations authentik
NAME        READY   MESSAGE                         REVISION        SUSPENDED
authentik   True    Applied revision: main/70da637  main/70da637    False
~ ❯

The helmrelease should be reconciled...

~ ❯ flux get helmreleases -n authentik authentik
NAME        READY   MESSAGE                             REVISION    SUSPENDED
authentik   True    Release reconciliation succeeded    v2023.10.x      False
~ ❯

And you should have happy pods in the authentik namespace:

~ ❯ k get pods -n authentik
NAME                                READY   STATUS      RESTARTS        AGE
authentik-redis-master-0            1/1     Running     1 (3d17h ago)   26d
authentik-server-548c6d4d5f-ljqft   1/1     Running     1 (3d17h ago)   20d
authentik-postgresql-0              1/1     Running     1 (3d17h ago)   26d
authentik-worker-7bb8f55bcb-5jwrr   1/1     Running     0               23h
~ ❯

Browse to the URL you configured in your ingress above, and confirm that the authentik UI is displayed.

Create your admin user

You may be a little confused re how to login for the first time. If you didn't use a bootstrap password as above, you'll want to go to https://<ingress-host-name>/if/flow/initial-setup/, and set an initial password for your akadmin user.

Now store the akadmin password somewhere safely, and proceed to create your own user account (you'll presumably want to use your own username and email address).

Navigate to Admin Interface → Directory → Users, and create your new user. Edit your user and manually set your password.

Next, navigate to Directory → Groups, and edit the authentik Admins group. Within the group, click the Users tab to add your new user to the authentik Admins group.

Eureka!

Your user is now an authentik superuser. Confirm this by logging out as akadmin, and logging back in with your own credentials.

Summary

What have we achieved? We've got authentik running and accessible, we've created a superuser account, and we're ready to flex the power of authentik to deploy an OIDC provider for Kubernetes, or simply secure unprotected UIs with proxy outposts!

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authentik resources 📝

• authentik (official site)

• authentik Discord

• authentik GitHub Repo

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