Migrate flowchart from dagre to elkjs

[redexp]

Hello, I was playing around with flowchart and really big diagram and find out that dagre has a lot issues with blocks positioning (like some blocks that has only one edge to other block in some subgroup unexpectedly far from that group, like across hole diagram) and with edges drawing which goes through other blocks.

I found good solution - elkjs it lot more configurable, smarter and can draw edges around a blocks

[mestaritonttu]

Dagre itself was recently declared unmaintained. In its issue tracker, people recommend elkjs or springy as alternatives.

[knsv]

This has been accentuated as dagre is not longer actively maintained. One problem with elkjs is its size though...

Mermaid is already a bit on the heavy side with:

We should be looking at lazy loading as well as investigating if tree-shaking works with elkjs. Have not seen any better options though.

[mestaritonttu]

Looking at the elkjs issue tracker, modularisation is definitely on their radar, but far from trivial due to the tooling used and other factors.

[knsv]

I think we should start with lazy loading in mermaid, this opens up for use of larger libraries

[richardtallent]

I'm having an issue with a site built with Vite, looks like it stems from this line in dagre's "greedy-fas" file:

var Graph = require("./graphlib").Graph;

This results in "Uncaught TypeError: Cannot read properties of undefined (reading 'Graph')".

Could be related to this issue. If so, I'd be willing to load the extra 100KB if it means I can keep using Mermaid. For now, I've had to remove it from my build, so my online docs have no fancy diagrams.

[Mizux]

FYI dagre is depreacted and lack of maintainers.

Important!
This project does not have a maintainer or active project members. There won’t be any support or attention to pull requests. Please do not contact previous maintainers unless you are qualified and have the resources to make a serious commitment to fully take over ownership of the project.

ref: https://github.com/dagrejs/dagre

Does mermaid dev will continue to maintain it ? (or you should drop this deps and find an alternative...)

[mestaritonttu]

In May 2022, a dagre contributor merged a couple of PRs from a new developer (build-related stuff). No announcement or undeprecation notice yet, but at least that is counter to "there won’t be any support or attention to pull requests" :)

elkjs is also still active and releases are being tagged.

[abitrolly]

https://github.com/eclipse/sprotty might provide an alternative.

[ghost]

We should do this sooner rather than later considering it's a high severity ReDoS

FYI current workaround is to add the following to package.json

  "resolutions": {
    "d3-color": "^3.1.0"
  }

[KartikSoneji]

Another issue with depending on dagre-d3 is it needs a browser env to run.
This means a fully headless cli is not possible, and a chrome or chromium instance will always be launched in the background, which is very resource intensive.

Migrating away from dagre might solve this issue.

[hermanussen]

It appears elkjs is being used from version 9.4.0 and up. However, since elkjs has an Eclipse Public License 2.0 (which is a copyleft license), this forces us (and any commercial closed source users) to use an older version of mermaid-js.

Is there no alternative?

[abitrolly]

Is there no alternative?

The alternative is to fork dagre and/or sponsor its development.

[alinamx]

It appears elkjs is being used from version 9.4.0 and up. However, since elkjs has an Eclipse Public License 2.0 (which is a copyleft license), this forces us (and any commercial closed source users) to use an older version of mermaid-js.

Is there no alternative?

I am facing the same issue right now.

[knsv]

We could move elkjs out to be an external diagram. This would make it possible for a site integrator to add elkjs by registering it when mermaid is initialized.

I am no legal expert but though, perhaps naively, that the copyleft license only would apply if you go in and make changes in the elkjs code. And that you then need to make those changes available to the original project.

[hermanussen]

I'm also not a legal expert. But I think if you put the usage of the Elk library into a separate npm package, that would solve the issue.

In order to avoid the Copyleft license, you would just install the main package. And not the Elk "plugin".

Of course, that would mean that the main package must be usable and useful without the plugin. I'm not familiar enough with mermaid-js to know if that would be possible or not.

[ted-marozzi]

We could move elkjs out to be an external diagram. This would make it possible for a site integrator to add elkjs by registering it when mermaid is initialized.

I am no legal expert but though, perhaps naively, that the copyleft license only would apply if you go in and make changes in the elkjs code. And that you then need to make those changes available to the original project.

This seems like the consensus here. I am not a legal expert but from what I can gather we can use elk in commercial software but any modifications to elk must be made public.

[abitrolly]

Looks like dagre is alive again. https://www.npmjs.com/package/@dagrejs/dagre?activeTab=versions Not sure if the maintainers found the funding, or there is another reason.