Redirect URLs using Google Cloud - google-cloud-platform

Question

I have a domain (example.com) already configured in Cloud DNS. With this domain I can access microservices that are in a GKE cluster. I use istio-ingressgateway IP in CloudDNS to make the association between the cluster
Now I have another domain (newexample.com) with a custom certificate for https connections. Is there a way to redirect all the requests to newexample.com to example.com? I do not want to change anything in gke/istio configuration if possible.

Answer 1

Each method will require some of the reconfiguration in either GKE/Istio side.
One of the solutions to this is to have a CNAME record in a Cloud DNS and a SSL certificate with Alternative Names.
With above solution you will be able to send requests to your GKE/Istio cluster with both domain names assuming correct Istio configuration.
What is CNAME?
CNAME is a Canonical Name Record or Alias Record.
A type of resource record in the Domain Name System (DNS), that specifies that one domain name is an alias of another canonical domain name.
Example of a CNAME record:
DNS name Type TTL Data
old.domain. A 60 1.2.3.4
new.domain. CNAME 60 old.domain.
Alternative Names:
A SAN or subject alternative name is a structured way to indicate all of the domain names and IP addresses that are secured by the certificate.
Enstrustdatacard.com: What is a san and how is it used
You can create SSL cerificate create to support both:
old.domain
new.domain
There are plenty options to do that for example Let's Encrypt or Cert Manager.
Example
I've created an example to show you how to do it:
Configure DNS zone in Cloud DNS
Create a basic app with a service
Create a certificate for example app
Create Istio resources to allow connections to example app
Test
Configure DNS zone in Cloud DNS
You will need to have 2 records:
A record with IP of your Ingress Gateway and name: old.domain
CNAME record pointing to old.domain with name: new.domain
Please take a look on official documentation: Cloud.google.com: DNS: Records
Create a basic app with a service
Below is example app with a service which will respond with a basic hello:
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-dp
spec:
selector:
matchLabels:
app: hello-dp
replicas: 1
template:
metadata:
labels:
app: hello-dp
spec:
containers:
- name: hello
image: "gcr.io/google-samples/hello-app:2.0"
env:
- name: "PORT"
value: "50001"
---
apiVersion: v1
kind: Service
metadata:
name: hello-sv
spec:
selector:
app: hello-dp
ports:
- name: hello-port
protocol: TCP
port: 50001
targetPort: 50001
type: ClusterIP
Create a certificate for example app
As said previously, certificate with Alternative Names can be created with Let's Encrypt. I created it with:
GCE VM with Ubuntu 16.04
Open port 80
Domain name old.domain pointing to public ip address of a VM
Guide: Linode.com: Docs: Install let's encrypt to create a SSL certificate
Command to create certificate:
$ ./letsencrypt-auto certonly --standalone -dold.domain-dnew.domain
Certificate created in /etc/letsencrypt/archive/ used in creating tls secret for GKE with command:
$ kubectl create secret tlsssl-certificate--cert cert1.pem --key privkey1.pem
Please have in mind that this certificate was created only for testing purposes and I strongly advise using dedicated solution like: Cert-manager
PS: If you used this method please revert back changes in the Cloud DNS to point the Istio gateway.
Create Istio resources to allow connections to example app
Below are example Istio resources allowing connections to example app with support for HTTPS:
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: hello-gw
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 443
name: https
protocol: HTTPS
tls:
mode: SIMPLE
credentialName: ssl-certificate
hosts:
- "old.domain"
- "new.domain"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: hello-vs
spec:
hosts:
- "old.domain"
- "new.domain"
gateways:
- hello-gw
http:
- route:
- destination:
host: hello-sv
port:
number: 50001
Please take a specific look on:
tls:
mode: SIMPLE
credentialName: ssl-certificate
This part will ensure that connection to the cluster will use HTTPS
Additionally:
hosts:
- "old.domain"
- "new.domain"
Above definition in both resources will allow only connections with specified domains.
Test
When applied all of the above resources you should be able to enter in your browser:
https://old.domain
https://new.domain
and be greeted with below message and valid SSL certificate:
Hello, world!
Version: 2.0.0
Hostname: hello-dp-5dd8b85b56-bk7zr