Google cloud loadbalancer Http-to-https with multiple backends

My goal is to have a redirect http-to-https for a loadbalancer for 3 instance groups on Google Cloud Platform.

I have one load-balancer http-to-https which redirects to another load-balancer for my 3 applications (3 backend services, 3 instance groups). I followed documentation, it works great for only 1 of those banckend-services, the ones which is default.The other 2 backends are not redirected to https when I curl the backend

not shown here, but IPs in both loadbalancers match

When I curl https://domain1.fr -> OK
When I curl http://domain1.fr -> 301 redirect to https -> OK

When I curl https://domain2.fr -> OK
When I curl http://domain2.fr -> OK (but no redirect to https)

When I curl https://domain3.fr -> OK
When I curl http://domain3.fr -> OK (but no redirect to https)

Not shown here, but if I change default backend to backend2 in my LoadBalancer, it redirects to https for domain2.fr.

You will have to add extra host and path rules to redirect http to https based on specific domain. This can be done in the google cloud console UI or using gcloud sdk.

1. In the UI,you can edit the LB and add a "new host and path rule", and set "Hosts" and "Host redirect" to your domain. Do this for each domain.

2. Using gcloud, you can export the URL map, modify the contents as below and upload it.

a. export existing url map -

gcloud compute url-maps export YOUR-URL-MAP --destination=/tmp/urlmap.yaml

The original yaml file will look like this for a single domain redirection web1.example.net -

name: webmap
kind: compute#urlMap
defaultUrlRedirect:
  hostRedirect: web1.example.net
  httpsRedirect: true
  redirectResponseCode: MOVED_PERMANENTLY_DEFAULT
  stripQuery: false

Add the second domain you want to redirect - in this case it is web2.example.net. Note the hostRules and pathMatchers section. You can add extra host rule and pathMatcher for each domain -

name: webmap
kind: compute#urlMap
defaultUrlRedirect:
  hostRedirect: web1.example.net
  httpsRedirect: true
  redirectResponseCode: MOVED_PERMANENTLY_DEFAULT
  stripQuery: false
hostRules:
- hosts:
  - web2.example.net
  pathMatcher: path-matcher-1
pathMatchers:
- defaultUrlRedirect:
    hostRedirect: web2.example.net
    httpsRedirect: true
    redirectResponseCode: MOVED_PERMANENTLY_DEFAULT
    stripQuery: false
  name: path-matcher-1

You can import this file -

gcloud compute url-maps import YOUR-URL-MAP --source=/tmp/urlmap.yaml

It will take a few minutes for the change to take effect.