Add support for diagrams.net (draw.io)

Input

<mxfile host="app.diagrams.net" modified="2020-10-03T15:11:57.367Z"
        agent="5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36"
        etag="11WjPOqNS_m0kgKlksbF" version="13.7.7" type="device">
  <diagram id="khsTyrV5h37nCq-FAsyN" name="Page-1">
    jZJNT8MwDIZ/TY6T2gb2caUMKgHiMAHTLihrTBMprassIx2/npS67appElIO8eOPxK/NeFo2j1bU6gUlGJZEsmH8niVJfJMkrD2RPHVkGS07UFgtKWgEG/0DBCOiRy3hMAl0iMbpegpzrCrI3YQJa9FPw77QTF+tRQEXYJMLc0k/tHSKukgWI89AF6p/OZ6vOk8p+mDq5KCERH+G+Jrx1CK67lY2KZhWvF6XLu/hinf4mIXK/Sfh/W32vKhXO8w+n+rtbpv5/euMqnwLc6SGs5CFAXm0Qaru5+7Uy2HxWEloK0aM33mlHWxqkbdeHxYgMOVKE6w4XKk2WAfN1U/HgxRhhwBLcPYUQiiB35J6tD58SbYfhxH3CquzQcyJCZp/MZQeJQoXUqk3x2n8+c52mq9/AQ==
  </diagram>
</mxfile>

Output

Please note that diagrams.net has an online viewer where the diagram hash (base64 deflate?) is used. The URL seems to be https://viewer.diagrams.net/?highlight=0000ff&edit=_blank&layers=1&nav=1#R + diagram hash.

For instance: https://viewer.diagrams.net/?highlight=0000ff&edit=_blank&layers=1&nav=1#RjZJNT8MwDIZ/TY6T2gb2caUMKgHiMAHTLihrTBMprassIx2/npS67appElIO8eOPxK/NeFo2j1bU6gUlGJZEsmH8niVJfJMkrD2RPHVkGS07UFgtKWgEG/0DBCOiRy3hMAl0iMbpegpzrCrI3YQJa9FPw77QTF+tRQEXYJMLc0k/tHSKukgWI89AF6p/OZ6vOk8p+mDq5KCERH+G+Jrx1CK67lY2KZhWvF6XLu/hinf4mIXK/Sfh/W32vKhXO8w+n+rtbpv5/euMqnwLc6SGs5CFAXm0Qaru5+7Uy2HxWEloK0aM33mlHWxqkbdeHxYgMOVKE6w4XKk2WAfN1U/HgxRhhwBLcPYUQiiB35J6tD58SbYfhxH3CquzQcyJCZp/MZQeJQoXUqk3x2n8+c52mq9/AQ==

Format:

• hello.svg
• hello.png
• hello.jpeg
• hello.pdf
• hello.vsdx (beta)

Runtime

JavaScript

Project

https://github.com/jgraph/mxgraph2

[Mogztter]

I took a look at https://github.com/jgraph/drawio and here’s my report:

• diagrams.net uses client-side (browser) export
• with a few changes to export.js it’s possible to use Puppeteer to load export3.html and convert a diagram
  • Chrome 90+ does not load the diagram properly using file:// protocol (even when if I forcibly disable web security) but it does work when using http://. It’s interesting to note that Firefox 87 does load the diagram properly using file:// or http://.
• diagrams.net provides a CLI as part of the Electron Desktop application
  • It take approximately ~1 second to convert Wireframe.xml to SVG
  • It’s not possible to pass the input as stdin
  • It’s not possible to output the result as stdout

Since diagrams.net CLI is relatively fast (and will require less maintenance), I think we should either install it as part of yuzutech/kroki or build a small HTTP server on top of the CLI and package it in a new Docker image yuzutech/diagramsnet.

For reference, @rlespinasse did some work to provide diagrams.net CLI as a Docker image: https://github.com/rlespinasse/docker-drawio-desktop-headless We can take some inspiration from this, most notably to disable auto-update functionality and clear output log from Electron.

[Mogztter]

Experimental support will land on the next release.

diagrams.net will be available as a companion container (yuzutech/kroki-diagramsnet) but will not be available on https://kroki.io right away. Once we have enough feedback, I will see if I can enable it on the public instance. Since we are very close to the memory limit, we will probably need to add more memory to run this additional container. Currently, Exoscale and all the sponsors do not cover all the expenses of the public instance, the remaining balance is around 40€/month. Upgrading from medium instances (4Gb - 2 cores) to large (8gb - 4 cores) will increase the cost by 60€/month. So unless I can find additional sponsors or convince Exoscale to give me more processing power it won’t happen 😞