4.9.5 broke site behind load balancer, forwards to localhost

[ssuess]

I have 2 wordpress web servers behind a load balancer. When updating from 4.9.4 to 4.9.5, these sites broke if accessed from the main domain (but continue to be accessible if I use their alternate addresses which is obvi not possible for our end users). Instead of the site loading by going to the main domain ​https://example.com, everyone who accesses the domain is instead directed to ​https://localhost.

As I said, if someone accessed ​https://wp1.example.com or ​https://wp2.example.com (the direct addresses), the sites work. For now, I have reverted to 4.9.4 which fixes the problem, but I would like to figure out a long term fix. Any suggestions?

FYI inside my wp-config files I am using these directives:

define('WP_SITEURL', 'https://' . $_SERVER['HTTP_HOST']);
define('WP_HOME', 'https://' . $_SERVER['HTTP_HOST']);

Which I need in place to be able to address the machines directly as well as having them work with the main domain via the load balancer.

I think I found the changeset responsible for this behaviour: [42894] but still have no workable fix.

[ssuess]

I was able to work around this and update by changing my wp-config directives to:

define('WP_SITEURL', 'https://' . $_SERVER['SERVER_NAME']);
define('WP_HOME', 'https://' . $_SERVER['SERVER_NAME']);

And also adding a param to my nginx conf to properly account for variable server names:

fastcgi_param SERVER_NAME $host;

without both of the above, my particular setup would not work properly.

[ssuess]

spoke too soon, all kinds of badly formatted page if connecting to load balancer, despite ssl insecure content fixer. Reverted to 4.9.4 and undid changes and problem went away.

[ssuess]

Still super broken....

[peterwilsoncc]

This was discussed in a triage session today.

As load balancers forward SSL headers and host headers in a variety of ways there's not much WordPress can do that's going to work universally.

The common solution is to hard code the values of $_SERVER['HTTPS'], WP_SITEURL and WP_HOME to match what is expected at the load balancer.

I saw you found the support forums for this, they are the best spot to ask so I am going to close this off as invalid, which is trac's unfriendly term to indicate this is best asked in support.