Self-Contained EXPORT_URL Issue with Reverse Proxy Base URL

[aque]

I run DRAWIO_SELF_CONTAINED: 1 behind an Nginx reverse proxy and a base url. I have the following DRAWIO_* values set. The application works except for the PDF export. This is because the ExportProxyServlet pointer is set to an explicit path.

      DRAWIO_SERVER_URL: https://host.domain.tld/draw/
      DRAWIO_BASE_URL: https://host.domain.tld/draw

Changing L31 to echo "window.EXPORT_URL = 'service/0'; and make it relative fixes the PDF export issue. I suppose L32 and L34 should follow that format but they were not tested.

docker-drawio/main/docker-entrypoint.sh

Lines 30 to 35 in bcda4f2

	if [[ "${DRAWIO_SELF_CONTAINED}" ]]; then
	echo "window.EXPORT_URL = '/service/0'; //This points to ExportProxyServlet which uses the local export server at port 8000. This proxy configuration allows https requests to the export server via Tomcat." >> $CATALINA_HOME/webapps/draw/js/PreConfig.js
	echo "window.PLANT_URL = '/service/1';" >> $CATALINA_HOME/webapps/draw/js/PreConfig.js
	elif [[ "${EXPORT_URL}" ]]; then
	echo "window.EXPORT_URL = '/service/0';" >> $CATALINA_HOME/webapps/draw/js/PreConfig.js
	fi

Edit: I forgot to mention that I am running v29.6.10.

[draw-io-triage-bot]

👋 Thank you for opening this issue!

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Summary: When running draw.io in self-contained mode behind a reverse proxy with a sub-path base URL (e.g., /draw/), the PDF export fails because EXPORT_URL is set to an absolute path (/service/0) which doesn't include the sub-path. The user proposes changing it to a relative path (service/0) in docker-entrypoint.sh to fix the issue.

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💡 Possible Solution Found

We found a potentially relevant solution in a previous issue:

The user has already identified the fix themselves: changing the EXPORT_URL from an absolute path to a relative path (service/0) in docker-entrypoint.sh L31. This is a legitimate bug when running behind a reverse proxy with a base URL path (e.g., /draw/). Related closed issue #128 addressed a similar PDF export failure, where the solution involved ensuring DRAWIO_BASE_URL and DRAWIO_SERVER_URL both use the full URL with protocol. However, that fix doesn't fully address the case where a sub-path is used. The user's proposed fix of making the EXPORT_URL relative (e.g., service/0 instead of /service/0) is the correct approach for sub-path reverse proxy setups, as relative URLs will respect the base URL path.

📎 Source: #128

Please check if this addresses your issue. If not, let us know what's different about your situation.

🔍 Possible Related Issues

This issue might be related to existing issues:

🔴 #192 - Self-Contained Export to PDF Fails with 500 Error
Both issues deal with self-contained PDF export failures; #192 may be caused by the same absolute vs relative URL issue when behind a reverse proxy.

🟡 #128 - Self-Contained Export to PDF Fails with 500 Internal Server Error
Same symptom (PDF export failure in self-contained mode), though #128 was caused by incorrect DRAWIO_BASE_URL format rather than the sub-path issue described here.

Please check if any of these address your issue. If this is a duplicate, we may close this issue and continue the conversation there.

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[aque]

The working solution of #192 uses the root path and not a base URL. #128 seems to point to an npm issue.