Using Multi-Site capabilities in Craft CMS v3.9 where HTTP_HOST isn't accurate

[GaryReckard]

I've got a site that is behind a Silverline WAF and Azure Front Door, it runs in a docker container, and for reasons I don't 100% understand, the actual hostname isn't getting passed through to Craft. If I output $_SERVER['HTTP_HOST'] it is just showing the IP address. (Same for $_SERVER['SERVER_NAME'])

I believe we've got things working for the single site by setting $_SERVER['HTTP_HOST'] based on an .env variable in the production environment. But now we're adding three new sites. The new sites are using unique subdirectories, such as /en-fr/ and /fr-fr/, and this is working great locally and on staging. But on production, visiting those subdirectories throws a 404.

I've tried a few things after some googling, but none of it has resolved the issue. I've tried setting the siteUrl value for each site manually in the general.php config:

        'siteUrl' => [
            'enUs' => $siteUrl,
            'enGb' => $siteUrl.'/en-gb/',
            'enFr' => $siteUrl.'/en-fr/',
            'frFr' => $siteUrl.'/fr-fr/',
        ],

Also, I originally had the new sites configured with a baseUrl like baseUrl: '@web/fr-fr/'. (The primary site uses baseUrl: 'https://$SITE_URL'). That wasn't working, so I tried changing that to something like baseUrl: '@web_frFr/'
and setting up these aliases in general.php:

        'aliases' => [
            '@web' => $siteUrl,
            '@web_enUs' => $siteUrl,
            '@web_enGb' => $siteUrl.'/en-gb/',
            '@web_enFr' => $siteUrl.'/en-fr/',
            '@web_frFr' => $siteUrl.'/fr-fr/',
        ],

but no luck there.

These attempts probably expose my lack of understanding + confusion about how all this really works...

Wondering if anyone has any suggestions on how to get this multi-site stuff to work in my type of setup. Sidenote: we do have plans to upgrade to Craft v4, but that's still maybe months away. We need to get these new regional sites up ASAP.

Thanks!

[angrybrad]

I can't think of (or find) anywhere in Yii or Craft where we write to either HTTP_HOST or SERVER_NAME.

We read from those values, sure. https://github.com/yiisoft/yii2/blob/master/framework/web/Request.php#L754-L777

I’ve never used Silverline WAF or Azure Front Door, but as a starting point, I’d focus on those to see if they are injecting values into those headers that Craft/Yii is just reading from.