GITBOOK-9: No subject

docs/advanced-features/url-prefix.md

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+# URL Prefix
+
+MediaManager, by default, expects to run at the base of a domain, e.g. `maxdorninger.github.io`.
+
+In order to run it on a prefixed path, like `maxdorninger.github.io/media`, the docker image must be built with a special build argument. That's because SvelteKit needs to know the base URL at build time.
+
+In short, clone the repository, then run:
+
+{% code title="Build Docker image" %}
+```none
+docker build \
+  --build-arg BASE_PATH=/media \
+  --build-arg VERSION=my-custom-version \
+  -t MediaManager:my-custom-version \
+  -f Dockerfile .
+```
+{% endcode %}
+
+You also need to set the `BASE_PATH` environment variable at runtime in `docker-compose.yaml`:
+
+* `BASE_PATH`\
+  Base path prefix MediaManager is served under. Example: `/media`. This must match the `BASE_PATH` build arg.
+
+{% code title="docker-compose.yaml (excerpt)" %}
+```yaml
+services:
+  mediamanager:
+    image: MediaManager:my-custom-version
+    ports:
+      - "8000:8000"
+    environment:
+      BASE_PATH: /media
+      ...
+```
+{% endcode %}
+
+{% hint style="info" %}
+Make sure to include the base path in the `frontend_url` field in the config file. See [Backend](../configuration/backend.md).
+{% endhint %}
+
+Finally, ensure that whatever reverse proxy you're using leaves the incoming path unchanged; that is, you should not strip the `/media` from `/media/web/`.