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This page collects Frequently Asked Questions of the community.
If you have any questions that aren't answered here, feel free to ask us on Matrix or stop by our community forums.
Why is CodiMD now called HedgeDoc?
The short version: There were two CodiMD-projects on GitHub, the community-driven fork and the original project maintained by the HackMD-team. To solve this naming conflict, our community-driven version was renamed to HedgeDoc. For a full writeup, check out the history overview.
Can I run multiple instances on the same database?
No. The HedgeDoc server process is not entirely stateless and therefore running more than one instance will result in missing/broken content for users. In order to solve issues like HA-capabilities, please use a high level orchestrator that makes sure that always 1 instance is running on your infrastructure and that the database is available. The server process usually starts within seconds and therefore the possible downtime should be minimal.
Why was the PDF Export feature removed?
We used a headless Chromium instance to generate the PDFs, but that led to some security vulnerabilities and was therefore deactivated.
There are currently plans to re-add this feature in a safe way, but this will most likely take some time and can be expected at the earliest with HedgeDoc 2.1 (but could also take longer).
In the meantime you can use your browsers print to PDF Feature.
This page explains how to do that for multiple browsers.
Why can't I embed some PDFs?
Many servers don't allow the embedding of their content on arbitrary sites.
For a more technical explanation:
The X-Frame-Options header can be used to specify if a given webpage can be embedded.
For security reasons this header is often set to SAMEORIGIN, which disallows embedding on other origins.
To be able to embed a PDF inside a HedgeDoc note, the server that hosts the PDF must either send no X-Frame-Options
header (which might be insecure) or include the URI of your HedgeDoc instance in an ALLOW-FROM statement.
See Mozillas docs for more details.
Also note that the X-Frame-Options header is being obsoleted
by the frame-ancestors statement in the Content-Security-Policy header.