Magento2: Admin too many redirect when use admin custom URL (SSL , varnish)

[tandih]

Preconditions

1. Magento 2.1.4
2. Php 7

Steps to reproduce

1. Setup Varnish, SSL, SSL forward with base URL (Not forward with admin custom Url)
   
2. Setup Magento admin to use custom URL that URL use http (not https)
3. Set unsecured base url in your default configuration to https config use SSL on front-end

Expected result

1. Back to admin with custom URL and login to admin panel success

Actual result

Get the error redirect loop in admin. Front-end work well

[sergi-omit]

@tanvandinh I had the same problem but i can fix modifying the nginx file configuration.

I use the nginx configuration included with the magento installation. And I change the PHP entry point to add the next params:

fastcgi_param  HTTPS "on";
fastcgi_param  HTTP_X_FORWARDED_PROTO "https";

So, the section of the php entry point must be:

# PHP entry point for main application
location ~ (index|get|static|report|404|503)\.php$ {
    try_files $uri =404;
    fastcgi_pass   fastcgi_backend;
    fastcgi_buffers 1024 4k;

    fastcgi_param  PHP_FLAG  "session.auto_start=off \n suhosin.session.cryptua=off";
    fastcgi_param  PHP_VALUE "memory_limit=768M \n max_execution_time=600";
    fastcgi_read_timeout 600s;
    fastcgi_connect_timeout 600s;

    fastcgi_index  index.php;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    fastcgi_param  HTTPS "on";
    fastcgi_param  HTTP_X_FORWARDED_PROTO "https";
    include        fastcgi_params;
}

[tandih]

Hi @sergi-omit,

Thank you for your information.
Did you use admin custom URL(domain point by local DNS) that URL use http (not https). I get the error when try to custom admin URL. I use Nginx configuration included with the Magento and add
fastcgi_param HTTPS "on";
fastcgi_param HTTP_X_FORWARDED_PROTO "https";
As you are mentions also but the errors does not fix. Currently we use default admin URL (the same with fron-end [base-url]/admin_**)
Would love any of comment or sugesstion on this ticket.

Thank you so much

[boscowitch]

This seems also to affect the normal URL in 2.1.x
Too many redirect when the proxy forces ssl for the admin url but the databse is still set to http.

so HTTPS "on" seems to be ignored from the admin panel and it still tries to redirect back to http, hence the loop with the transparent https proxy in front of it redirecting everything to https....

In my opinion it should not force http through db settings since http is default but only force https if required.

[ghost]

@tanvandinh close this issue as duplicate ->https://github.com/magento/magento2/issues/17556

[vtransy]

please set: web/secure/use_in_frontend and web/secure/use_in_adminhtml to 0

Please read here for more detail:
https://mrvts.wordpress.com/2018/12/17/magento-2-nginx-varnish-full-page-cache-backend-admin-redirect-loop-why-and-how-to-fix/