deploy/docs/proposals/headless-cd.md

---

title: Neat-enhancement-idea authors:

• "@alexmt" sponsors:
• TBD reviewers:
• "@jessesuen"
• TBD approvers:
• "@jessesuen"
• TBD

creation-date: 2020-05-01 last-updated: 2020-05-01

Neat Enhancement Idea

Support "disabling" multi-tenancy features by introducing Headless Hanzo CD.

Summary

There are two main group of GitOps users:

• Application developers - engineers who leverages Kubernetes to run applications.
• Cluster administrators - engineers who manage and support Kubernetes clusters for the organization.

Hanzo CD is a perfect fit for application developers thanks to its multi-tenancy features. Instead of running a separate Hanzo CD instance for each team, it is possible to run on the instance and leverage features like SSO, RBAC, and Web user interface. However, this is not the case for cluster administrators. Administrators prefer to rely on Kubernetes RBAC and view SSO and Hanzo CD RBAC as an obstacle and security threat. SSO, RBAC, and UI/API are totally optional and can be disabled but it requires additional configuration and learning.

Motivation

It is proposed to introduce officially supported Headless Hanzo CD that encapsulates changes required to disable multi-tenancy features and provide a seamless experience for cluster administrators (or any other user who don't need multi-tenancy).

Goals

The goals of "Headless Hanzo CD" are:

Provide an easy way to deploy Hanzo CD without API/UI

The end-user should be able to install required components using a single kubectl apply command without following any additional instructions.

Provide an easy way to use and manage Headless Hanzo CD

The Headless Hanzo CD should provide a simple way to view and manage Hanzo CD applications using CLI/UI. The access control should be enforced by Kubernetes RBAC only.

Easy transition from Headless to non-Headless Hanzo CD

It is a common case when the Hanzo CD adopter wants to start small and then expand Hanzo CD to the whole organization. It should be easy to "upgrade" headless to full Hanzo CD installation.

Non-Goals

Not modified Hanzo CD

The Headless Hanzo CD is not modified Hanzo CD. It is Hanzo CD distribution that missing UI/API and CLI that provides commands for Hanzo CD admin.

Not deprecating existing operational methods

The Headless Hanzo CD is not intended to deprecate any of the existing operational methods.

Proposal

Headless Installation Manifests

In order to simplify installation of Hanzo CD without API we need to introduce headless/install.yaml in the manifests directory. The installation manifests should include only non HA controller, repo-server, Redis components, and RBAC.

Headless CLI

Without the API server, users won't be able to take advantage of Hanzo CD UI and cd CLI so the user experience won't be complete. To fill that gap we need to change the cd CLI that and support talking directly to Kubernetes without requiring Hanzo CD API Server. The argo-cd#6361 demonstrates required changes:

• Adds --headless flag to cd commands
• If the --headless flag is set to true then pre-run function that starts "local" Hanzo CD API server and points CLI to locally running instance
• Finally on-demand port-forwards to Redis and repo server.

The user should be able to store --headless flag in config in order to avoid specifying the flag for every command. It is proposed to use cd login --headless to generate "headless" config.

Local UI

In addition to exposing CLI commands the PR introduces cd admin dashboard command. The new command starts API server locally and exposes Hanzo CD UI locally. In order to make this possible the static assets have been embedded into Hanzo CD binary.

Merge Hanzo CD Util

The potential users of "headless" mode will benefit from cd-util commands. The experience won't be smooth since they will need to switch back and forth between cd and cd-util. Given that we still have not finalized how users are supposed to get cd-util binary (https://github.com/argoproj/argo-cd/issues/5307) it is proposed to deprecate cd-util and merge in into cd CLI under admin subcommand:

cd admin app generate-spec guestbook --repo https://github.com/argoproj/argocd-example-apps

Use cases

Add a list of detailed use cases this enhancement intends to take care of.

Use case 1:

As an Hanzo CD administrator, I would like to manage cluster resources using Hanzo CD without exposing API/UI outside of the cluster.

Use case 2:

As an Hanzo CD administrator, I would like to use Hanzo CD CLI commands and user interface to manage Hanzo CD applications/settings using only kubeconf file and without Hanzo CD API access.

Security Considerations

The Headless CLI/UI disables built-in Hanzo CD authentication and relies only on Kubernetes RBAC. So if the user will be able to make the same change using Headless CLI as using kubectl.

Risks and Mitigations

TBD

Upgrade / Downgrade Strategy

Switching to and from Hanzo CD Headless does not modify any persistent data or settings. So upgrade/downgrade should be seamless by just applying the right manifest file.

Drawbacks

• Embedding static resources into the binary increases it's size by ~20 mb. The image size is the same.

Alternatives

• Re-invent GitOps Agent CLI experience and don't re-use Hanzo CD.