Docs: Clarify from-to-www redirect direction.

[chakrit]

This was not clear to me when reading the docs whether the ingress will redirect from non-www to with-www or the reverse. It's also not very clear from just grepping around the codebase. I found the answer by reading from this reddit link:

https://www.reddit.com/r/kubernetes/comments/pbl033/k8s_ingress_redirecting_www_to_nonwww_domains/

So, to save time for other people doing the same, which I assumes is a lot of people since it's a common scenario, I believe this little revision in the docs is warranted.

What this PR does / why we need it:

Update the docs to clarify, when setting from-to-www-redirect, which direction of redirection is going to be performed.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

How Has This Been Tested?

Ran mkdocs and things seemed fine.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: chakrit / name: Chakrit Wichian (e1a5d5c)
• ✅ login: Gacko / name: Marco Ebert (d0199ab)

[k8s-ci-robot]

Welcome @chakrit!

It looks like this is your first PR to kubernetes/ingress-nginx 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes/ingress-nginx has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[k8s-ci-robot]

Hi @chakrit. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[netlify]

✅ Deploy Preview for kubernetes-ingress-nginx canceled.

Name	Link
🔨 Latest commit	d0199ab
🔍 Latest deploy log	https://app.netlify.com/sites/kubernetes-ingress-nginx/deploys/66a47e8ebde4a5000816159c

[Gacko]

/triage accepted
/kind documentation
/priority backlog
/lgtm
/hold
/cc @longwuyuan

@longwuyuan Unhold if LGTY.

[Gacko]

/cherry-pick release-1.10

[Gacko]

/cherry-pick release-1.11

[chakrit]

I'm burned out today, will comeback in a day or so and try looking at the tests and adding that paragraph if someone hasn't already added it. Thanks!

[Gacko]

From to.app.gacko.io to www.to.app.gacko.io:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: www-to-app-gacko-io
  namespace: default
  annotations:
    nginx.ingress.kubernetes.io/from-to-www-redirect: "true"
spec:
  ingressClassName: nginx
  rules:
  - host: www.to.app.gacko.io
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: hello-world
            port:
              number: 80

% curl --verbose --silent "http://to.app.gacko.io" --output /dev/null
* Host to.app.gacko.io:80 was resolved.
* IPv6: (none)
* IPv4: 18.170.90.51, 18.175.29.196, 13.42.193.94
*   Trying 18.170.90.51:80...
* Connected to to.app.gacko.io (18.170.90.51) port 80
> GET / HTTP/1.1
> Host: to.app.gacko.io
> User-Agent: curl/8.6.0
> Accept: */*
> 
< HTTP/1.1 308 Permanent Redirect
< Date: Fri, 26 Jul 2024 14:27:40 GMT
< Content-Type: text/html
< Content-Length: 164
< Connection: keep-alive
< Location: http://www.to.app.gacko.io
< 
{ [164 bytes data]
* Connection #0 to host to.app.gacko.io left intact

From www.from.app.gacko.io to from.app.gacko.io:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: from-app-gacko-io
  namespace: default
  annotations:
    nginx.ingress.kubernetes.io/from-to-www-redirect: "true"
spec:
  ingressClassName: nginx
  rules:
  - host: from.app.gacko.io
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: hello-world
            port:
              number: 80

% curl --verbose --silent "http://www.from.app.gacko.io" --output /dev/null  
* Host www.from.app.gacko.io:80 was resolved.
* IPv6: (none)
* IPv4: 18.170.90.51, 18.175.29.196, 13.42.193.94
*   Trying 18.170.90.51:80...
* Connected to www.from.app.gacko.io (18.170.90.51) port 80
> GET / HTTP/1.1
> Host: www.from.app.gacko.io
> User-Agent: curl/8.6.0
> Accept: */*
> 
< HTTP/1.1 308 Permanent Redirect
< Date: Fri, 26 Jul 2024 14:28:13 GMT
< Content-Type: text/html
< Content-Length: 164
< Connection: keep-alive
< Location: http://from.app.gacko.io
< 
{ [164 bytes data]
* Connection #0 to host www.from.app.gacko.io left intact

[longwuyuan]

thanks. my test was wrong.

[Gacko]

I implemented the suggestions, hope this is fine for you @chakrit!

[Gacko]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chakrit, Gacko

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [Gacko]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[Gacko]

@longwuyuan Can we get this PR merged in its current state?

[longwuyuan]

Hi yes is my opinion because you added that helpful description . Thank you.

…

On Mon, 29 Jul, 2024, 13:12 Marco Ebert, ***@***.***> wrote: @longwuyuan <https://github.com/longwuyuan> Can we get this PR merged in its current state? — Reply to this email directly, view it on GitHub <#11682 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABGZVWRVIDJOGJFVJBBROXTZOXXAHAVCNFSM6AAAAABLP7OH5SVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDENJVGIZDSMJXGY> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[Gacko]

/unhold

[k8s-infra-cherrypick-robot]

@Gacko: new pull request created: #11692

In response to this:

/cherry-pick release-1.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[k8s-infra-cherrypick-robot]

@Gacko: new pull request created: #11693

In response to this:

/cherry-pick release-1.11

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[dvglab]

Hey guys, it looks like new documentation totally wrong:
For example, if .spec.rules.host is configured with a value like www.example.com, then this annotation will redirect to example.com.

But in reality it should be like this:
For example, if .spec.rules.host is configured with a value like example.com, then this annotation will redirect www.example.com to example.com

Waste about 3 hours of life before got it.

[Gacko]

It's working in both ways. We tested this. See my comments from above. 🙂

[Gacko]

But yeah, thinking about it, it's not really the best. Feel free to open a PR!

[dvglab]

It's working in both ways. We tested this. See my comments from above. 🙂

Yep, but the problem is in the description. Once again, reading documentation literally "if .spec.rules.host is configured with a value like www.example.com, then this annotation will redirect to example.com." But it will NOT redirect to example.com, it will redirect FROM example.com TO www.example.com. That's the trick. And yes we can see it in your comments from above.

I'll open PR, thank you.

[dvglab]

Opened PR #11712 (comment)