# Serve Discourse from a subfolder (path prefix) instead of a subdomain

**URL:** https://meta.discourse.org/t/serve-discourse-from-a-subfolder-path-prefix-instead-of-a-subdomain/30507
**Category:** Self-Hosting
**Tags:** docker, subfolder, how-to, advanced-setup
**Created:** [June 26, 2015, 7:18pm UTC](https://meta.discourse.org/t/serve-discourse-from-a-subfolder-path-prefix-instead-of-a-subdomain/30507 "2015-06-26T19:18:04Z")
**Posts on this page:** 1
**Showing post:** 129

<div class="post-metadata">

### Author: ![MichaIng](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/michaing/32/251089_2.png) [@MichaIng](https://meta.discourse.org/u/MichaIng)
#### Post date: [April 14, 2026, 9:15pm UTC](https://meta.discourse.org/t/serve-discourse-from-a-subfolder-path-prefix-instead-of-a-subdomain/30507/129 "2026-04-14T21:15:09Z")

</div>

Since a while, we see `X-Accel-Mapping header missing` messages emitted by the container in a quite high frequency, but not triggered by every visitor or ever navigation step. I see that this header is explicitly defined in the Nginx config, though not for all requests: [discourse/config/nginx.sample.conf at main · discourse/discourse · GitHub](https://github.com/discourse/discourse/blob/main/config/nginx.sample.conf)

Since I cannot see this reported anywhere else in this forum, I wonder whether it could be related to the subdir setup we use, though I do not see how.

Not sure what exactly is emitting it, but I guess this should happen only if `X-Sendfile-Type` is set to `X-Accel-Redirect`, but `X-Accel-Mapping` is not set. And the config only defines both, or sets both empty 🤔.

Actually it is set only when accessing backups, and, more relevant, when accessing uploads. Just tested and verified, that whenever I view a post with an uploaded image or similar, it triggers that message. Looking at the config, it should not be possible that `X-Accel-Redirect` is set but `X-Accel-Mapping` not. Also this is a request header set by Nginx within the container, consumed by Discourse/unicorn/pitchfork/backend only, i.e. it does not enter or leave the container at all.

Ah, we configure Nginx to log to STDERR, and since I do not see this in Discourse logs, I am sure Nginx itself emits it. This is probably the reason it has not been recognized by anyone else, as it is in the Nginx log file. Does someone find time to check whether their `shared/*/log/var-log/nginx/error.log` contains these as well? If so, I’d check back with others who do not use a subdir setup, to narrow it down.

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_[View the full topic](https://meta.discourse.org/t/serve-discourse-from-a-subfolder-path-prefix-instead-of-a-subdomain/30507)._