Drake: Re-distribute Gurobi in Drake binary releases

[RussTedrake]

_Edit: The original issue title was "Can users with a gurobi license (and no snopt license) use gurobi AND snopt?". We've retitled to reflect a new consensus now._

I wasn't able to find any documentation about this on our site. perhaps we can add it?

Can (or does) the binary distribution include gurobi bindings, but fail if the gurobi libraries aren't found?

I believe the alternative (having someone build from source and get snopt, despite not having the snopt source) is much harder to achieve?

@jamiesnape -- tagging you to get the current status first.

[jamiesnape]

No, we don't support providing your own commercial solver licenses or libraries at present. Enabling Gurobi support is currently a compile-time decision. We could add support for loading commercial solvers at runtime if available, but it would be an architectural change.

[jwnimmer-tri]

... and to further clarify the _"add support for loading commercial solvers at runtime if available"_:

That would entail linking or loading solvers/gurobi_solver.pic.o, not just libgurobi80.so. Even with the delayed load of gurobi, we cannnot ship solvers/gurobi_solver.pic.o in any binary release, because it is a derived work of gurobi_c.h and we do not have (to my knowledge) permission to redistribute derived works of this form.

[RussTedrake]

i understand. thanks.

just to collect all of these thoughts in one place... the other alternative, I would think, is to have gurobi_solver.o always in the binary release, and have it check the license file (instead of loading the obj file) to confirm availability. would this be better? (conditional on us obtaining permission for redistributing it)

[jamiesnape]

Even with the delayed load of gurobi, we cannnot ship solvers/gurobi_solver.pic.o in any binary release, because it is a derived work of gurobi_c.h and we do not have (to my knowledge) permission to redistribute derived works of this form.

My reading of EULA suggests that part would not necessarily be a problem, but someone would need to check for any (other) constraints.

[jamiesnape]

just to collect all of these thoughts in one place... the other alternative, I would think, is to have gurobi_solver.o always in the binary release, and have it check the license file (instead of loading the obj file) to confirm availability. would this be better? (conditional on us obtaining permission for redistributing it)

I think we probably want a license check as well regardless to be nice to the end-user.

[jwnimmer-tri]

@RussTedrake The easiest solution along those lines would be if we have permission to redistribute _both_ the gurobi80.so library _as well as_ our object code derived works of gurobi_c.h such as solvers/gurobi_solver.pic.o, subject to Gurobi's default built-in license-checking. In that case, we can just enable it in binary releases by default with minimal code changes -- I guess just check the license prior to ChooseBestSolver making a decision, and tuning up any install glue code.

If we only have permission to redistribute solvers/gurobi_solver.pic.o, then we cannot unconditionally link gurobi80.so in the default release -- so either we'd need to make a new binary release flavor, or split out a -ldrake_solvers_gurobi mini-library, or use dlopen, or etc.

[jamiesnape]

My thoughts were along the lines of a dlopen of gurobi80.so, but certainly plenty of reasons to want to avoid that, if at all possible.

[EricCousineau-TRI]

Just to check: Can I ask what situation this accommodates, or what use case?
Is this to check alternatives against SNOPT (given the current version / config ping pong that we're playing)?

[jwnimmer-tri]

My impression of the user story was "Most people are happy to just use Drake binary releases. If they have a (site) license to Gurobi, it would be nice if that Just Worked out of the box. The need is especially acute for users _without_ a site license to SNOPT -- in that case, even if they compile from source in order to use Gurobi, they then lose the ability to use SNOPT".

[RussTedrake]

correct. and that happens to account for most of the academic world, as gurobi is free for academics, but SNOPT is not.

[tri-ltyyu]

Use case understood. Is there a research group/class actively blocked by this to gauge timing? Wondering if there's a work around such as using Colab or asking the dept. to get a license for $600.

[jwnimmer-tri]

Since the next action on this issue is to see if MIT has the right to redistribute Gurobi stuff (per details above), maybe the easy answer is to reassign this issue to Russ, and he can pursue that question with MIT legal on whatever pace it requires?

[jwnimmer-tri]

I guess @tri-ltyyu could also own it and chase down MIT legal. All I'm really saying is that @jamiesnape isn't an appropriate assignee anymore.

[tri-ltyyu]

Happy to chase someone down to find out, but want to confirm if it's MIT legal or Gurobi legal that we want to get permission from? From Gurobi's EULA, I see the following, which makes me think we need permission from them first?
"You may not use, copy, modify, or distribute the Product, or make any copy, adaptation, transcription, or merge any portion thereof, unless expressly authorized by Gurobi in a separate written agreement."

[jamiesnape]

Ultimately, it would need to be Gurobi. Whether it is you or Russ or MIT who makes the request to Gurobi is a slightly different question. The license on CI is officially assigned to MIT CSAIL with Russ as the administrator.

[jwnimmer-tri]

... just check the license prior to ChooseBestSolver making a decision ...

FYI #13279 has implemented this now.

[jamiesnape]

Note, I don't know of a license that would work for Colab, even if we could redistribute. Pretty much all of Gurobi's licenses end up being attached to either a MAC address or a subnet.

[jamiesnape]

(Gurobi Cloud is their product and it is a different architecture to the C library)

[RussTedrake]

Just noticed this for the first time: https://www.gurobi.com/license-center/for-online-courses/ I wonder if that changes anything?

[jamiesnape]

Difficult to say for certain. Probably not, but it could give you a different avenue to talking to Gurobi. The redistribute part of the license is the problem, and I do not suppose the new license changes that. I doubt it changes anything for Colab, for example.