Login-As-Customer and Varnish conflict

[webloft]

Preconditions and environment

We found out that Login-As-Customer attempt only works randomly with Varnish and there is a simple reason for that:

• The VCL declares that GET/HEAD requests should filter Set-Cookie-headers:

if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD")) {
        unset beresp.http.set-cookie;
}

• The Login-As-Customer module JS opens a GET /loginascustomer/login/index/?secret=*** request and resets the PHP session id
• Resetting the PHP session id will issue a Set-Cookie-Header with the new session id
• The cookie header will be ignored by Varnish
• The login fails since the browser doesn't know the new session id and stills sends the old one

Steps to reproduce

Enable & configure Varnish and try to login as customer

Expected result

Login as customer session works.

Actual result

Login as customer MAY work.

If you are lucky, the session will be recognized - or not if Varnish delivers a cached version.

Additional information

The issue can be bypassed by configuring the VCL:

# Bypass shopping cart, checkout and search requests
if (req.url ~ "/customer" || req.url ~ "/checkout" || req.url ~ "/loginascustomer") {
        return (pass);
}

...

# validate if we need to cache it and prevent from setting cookie
if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD") && !(bereq.url ~ "/loginascustomer")) {
        unset beresp.http.set-cookie;
}

but should be done correctly by the module itself by sending a Cache-Control: private header.

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @webloft. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, Add a comment to the issue:

• @magento give me 2.4-develop instance - upcoming 2.4.x release
• For more details, review the Magento Contributor Assistant documentation.
• Add a comment to assign the issue: @magento I am working on this
• To learn more about issue processing workflow, refer to the Code Contributions.

---

Join Magento Community Engineering Slack and ask your questions in #github channel.
⚠️ According to the Magento Contribution requirements, all issues must go through the Community Contributions Triage process. Community Contributions Triage is a public meeting.
🕙 You can find the schedule on the Magento Community Calendar page.
📞 The triage of issues happens in the queue order. If you want to speed up the delivery of your contribution, join the Community Contributions Triage session to discuss the appropriate ticket.

[m2-assistant]

Hi @engcom-Bravo. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.

[engcom-Bravo]

Hi @webloft,

Thanks for your reporting and collaboration.

We have verified the issue in Latest 2.4-develop instance and the issue is not reproducible.Kindly refer the screenshots.

Login as customer session is working.

Thanks.

[webloft]

@engcom-Bravo Did you get the part that the a new session cookie may be set via GET-request?

We didn't see the new cookie unless we modified the VCL to not filter it out. And withtout the cookie, the session was not working.

[m2-assistant]

Hi @engcom-Hotel. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.