Support for choosing the layout engine for D2 in GitLab code blocks

[mak-dunkelziffer]

Support for choosing the layout engine for D2 in GitLab code blocks

[ggrossetie]

This is an integration issue with GitLab/Markdown. Kroki already supports it (see below).

You will need to open an issue at https://gitlab.com/gitlab-org/gitlab/-/issues to support sending diagram options to the Kroki server. Regarding which Markdown syntax we should use, I don't have a strong opinion. AsciiDoc has built-in support for attributes:

[d2,layout=elk]
....
# my diagram
....

Please note that TALA is a proprietary engine and is not included in Kroki. It might be possible to add it by extending the base image.

Default layout (diagre)

https://kroki.io/d2/svg/eNqlUj1vgzAQ3f0r7g-EpZuHSlW7MLRFSpgrC07BwsGWfTRCEf-9Z2MimlYZ2gF0H37P7-7Z2GOQcBEAoVMOJTh1xJjRZLA4jYa0M1wmP6KYxRjQS6j5D5cVgD7YYRYD0tn6XsLbEiRSsucIeEZj4BDjVGV6RVzShPnyVFv4AlmP7UerSK2N37TExixuyGD3yF01hJMmQv_v7vd85s9522AIlod6YYVQrfk6GKvnDUrYL8HtdM1k9NBm-ruj5fusJ2UkvA-MQ6hSmknrUuQdpDUXG7VxmI1U11kGG_aaPWTzPqMpT1UJ-xSL5GvEZBOL7Nur6hEaZczqbnEljacXpj_3spJYSdLupstD04G2sCt7WktRlxJaHZxR04-JNkdUE6Usjz7tP5C3Pe5aFToJD7yiL8hLBuk=

ELK layout

https://kroki.io/d2/svg/eNqlUj1vgzAQ3f0r7g-EpZuHSlW7MLRFSpgrC07BwsGWfTRCEf-9Z2MimlYZ2gF0H37P7-7Z2GOQcBEAoVMOJTh1xJjRZLA4jYa0M1wmP6KYxRjQS6j5D5cVgD7YYRYD0tn6XsLbEiRSsucIeEZj4BDjVGV6RVzShPnyVFv4AlmP7UerSK2N37TExixuyGD3yF01hJMmQv_v7vd85s9522AIlod6YYVQrfk6GKvnDUrYL8HtdM1k9NBm-ruj5fusJ2UkvA-MQ6hSmknrUuQdpDUXG7VxmI1U11kGG_aaPWTzPqMpT1UJ-xSL5GvEZBOL7Nur6hEaZczqbnEljacXpj_3spJYSdLupstD04G2sCt7WktRlxJaHZxR04-JNkdUE6Usjz7tP5C3Pe5aFToJD7yiL8hLBuk=?layout=elk

[mak-dunkelziffer]

Thank's for the fast reply. Good to know that AsciiDoc supports this out of the box. I guess the chances to make a syntax change happen in Markdown are pretty slim. Instead, I opened an issue for D2 itself to make it possible to set those params within the diagram itself.

[ggrossetie]

Using d2elk or d2tala could work but the integration will need to translate it to d2 using elk or tala layout engine.
It also does not scale very well if you want to add another option (i.e., d2talanoborder 😬)

I think it's a good idea to set those parameters within the diagram itself.

[mak-dunkelziffer]

I actually tried d2elk and d2-elk and hoped that Kroki would just support one of those. But this approach really isn't feasible. D2 has too many CLI options. It has a theme option with ~20 options, a boolean sketch option, 3 layout engines. You simply can't support all possible combinations.

Also, having to specify the layout engine on the CLI is actually REALLY cumbersome, because the layout engines support slightly different features. Thus, your diagrams are not self-contained anymore, because they might use a feature, that only one layout engine understands and you need to guess that engine when compiling the diagram.