Impossible to use Google Cloud CDN cache with ingress controller, Transfer-Encoding header

Question

I try to configure Google Cloud CDN to my container engine project.

Following the documentation It has either a Content-Length header or a Transfer-Encoding header in order to be cached.

My backend use gzip compression so I have Transfer-Encoding: chunked

The problem is it seems the ingress load balancer remove the Transfer-encoding header so I can't have a "cache hit"

I used "kubectl port-forward" to connect direclty to an instance backend and I have the Transfer-encoding header.

But when I connect to the external IP, the header has disappear.

Here my ingress configuration

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: gateway-preprod3-ingress
  annotations:
    kubernetes.io/ingress.global-static-ip-name: gateway-preprod2-static-ip
spec:
  tls:
  - secretName: gateway-preprod-secret-2018-with-ca-7
  backend:
    serviceName: gateway-preprod
    servicePort: 80

Here my deployment configuration

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: gateway-preprod
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
  minReadySeconds: 50
  template:
    metadata:
      labels:
        app: gateway-preprod
    spec:
      containers:
      - name: gateway-preprod
        image: eu.gcr.io/writecontrol-1055/gateway:v305
        env:
        - name: writecontrolEnv
          value: preprod
        ports:
        - containerPort: 80

In the opposite, for certain ressources not GZIP compressed, the Content-length header is given and I have a successful "cache hit"

The kubernetes version is 1.7.12-gke.1

Here an URL to test it : https://preprod-writecontrol.ovh

Which documents you are using to deploy your CDN over GKE?. What's the exact request you are using to test the CDN?. Additionally, you need to check this documentation on 'Ilegal request handling', where it explains a number of reasons for a LB blocks the client request from reaching the back-end. — Digil
All static resources can be tested : for example preprod-writecontrol.ovh/bower_components/webcomponentsjs/… I have response for load balancer . The problem is I don't have a header that my backend sent => Transfer-encoding — maxiplay
Can you provide me the documents which I have requested in my previous message ? This would help me to reproduce the issue. Additionally, you might need to check this basic troubleshooting guide for common Cloud CDN problems. See if that helps you as well. — Digil
I don't understand your question. You speak about documentation ? Here it is cloud.google.com/cdn/docs/caching Or you speak about the cdn configuration ? I use the Default I already check the documentation cloud.google.com/cdn/docs/support — maxiplay
I could not reproduce this issue. It looks like you have already checked this documentation where they have mentioned possible causes for 'Compression isn't working'. At this point, if the issue still persists on your end, I suggest you to open a defect report via this issue tracker — Digil

Ahmet Alp Balkan Ahmet Alp Balkan · Accepted Answer · 2018-03-27T19:43:52

I am not sure why your response has Transfer-Encoding header. This header is not meant to be at the source (your application) and it is usually added by other hops, such as proxies like Cloud HTTP Load Balancer (=Ingress).

More info on Transfer-Encoding here: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding

I was able to get CDN working with a GZIP response myself using the Content-Encoding header instead:

First read the caching requirements at https://cloud.google.com/cdn/docs/caching. You need a Content-Length and/or Cache-Control: public header. So code these headers into your application server.

After enabling CDN on the load balancer created by Ingress, make two requests, and if you see Age header on the second request (as I did below), it means your request is now being served from CDN.

curl -vH Accept-Encoding:gzip 35.186.195.233
> [...]
>
< HTTP/1.1 200 OK
< Content-Encoding: gzip
< Date: Tue, 27 Mar 2018 19:38:20 GMT
< Content-Length: 87
< Content-Type: application/x-gzip
< Via: 1.1 google
< Cache-Control: max-age=600,public

��H����Q(�/�IQ�
* Connection #0 to host 35.186.195.233 left intact
K-*��ϳR0�3�3���/.�K�M�R�)+OM�55575��L�4ѭ�N+L���K��4A

And the second request (note the Age header):

$ curl -vH Accept-Encoding:gzip 35.186.195.233
[...]
>
< HTTP/1.1 200 OK
< Cache-Control: max-age=600,public
< Content-Encoding: gzip
< Date: Tue, 27 Mar 2018 19:42:01 GMT
< Content-Length: 87
< Content-Type: application/x-gzip
< Via: 1.1 google
< Age: 314
<
��H����Q(�/�IQ�
* Connection #0 to host 35.186.195.233 left intact
K-*��ϳR0�3�3���/.�K�M�R�)+OM�55575��L�4ѭ�N+L���K��4A

Impossible to use Google Cloud CDN cache with ingress controller, Transfer-Encoding header

1 Answers