Chris McGrath neoakris

Guide to doing a GKE HTTPS Cert Cutover from cluster1 to cluster2 with zero downtime

How to use:

Edit the input variables at the top
Copy paste steps one at a time into a bash/zsh terminal shell This will give better feedback and understanding of whats going on.

What to expect in this doc:

Traefik 2.0 has traffic mirroring functionality that should work on generic Kubernetes, but there's no good how-to guides, let this be the first.
This is a how-to guide, that's optimized for understanding

Background Context:

Question: What is a helm chart?
Answer: helm charts are just templating engines that render generated yaml
- input variables (with a mix of default and override values for those variables)
- get plugged into golang templatized yaml
- and output a wall of text of generated yaml
Community Helm Charts:

The following is based on 2 GCP / GKE How to Guides:

What this adds is additional checks / verification commands that can be run to help troubleshoot.

	# This is a tutorial (how to guide optimized for learning)
	# This is meant to be copy pasted line by line in bash
	# A speed run of this method is available here:
	# https://gist.github.com/neoakris/f1c4b329901811360ce6269ca631c80b

	# Set Input Vars (likely need to edit)
	export PROJECT=my-gcp-project
	export SA_SHORT_NAME=gcr-sa

	# Additional Input Vars (can skip editing)

	#!/bin/bash
	# A tutorial (learning optimized how to guide) of this same content with additional explanations is available here:
	# https://gist.github.com/neoakris/bd53146a7a610253abdbc1234ffb357b

	# Set Input Vars (likely need to edit)
	export PROJECT=my-gcp-project
	export SA_SHORT_NAME=gcr-sa

	# Additional Input Vars (can skip editing)
	export SA_NAME=$SA_SHORT_NAME@$PROJECT.iam.gserviceaccount.com

	tee original-managedcert.yaml << EOF
	apiVersion: networking.gke.io/v1
	kind: ManagedCertificate
	metadata:
	name: managed-cert
	spec:
	domains:
	- example.test
	EOF