Gurobi is not reading license settings from GurobiConfiguration

[23h...@gmail.com]

I got a license for Gurobi cloud but when I pass the values of access ID, cloud key, and cloud pool through GurobiConfiguration, Gurobi doesn't recognize them. It instead uses whatever values exist in c:\gurobi\gurobi.lic  if that file exists, otherwise none. Could you figure out whether the issue is on your end?

Specifically, my code looks something like:

var gurobiConfig = new GurobiSolverConfiguration { TimeLimit = 300, CloudAccessID = "foo", CloudPool = "bar", CloudSecretKey = "baz" };

using (var solver = new GurobiSolver(gurobiConfig))

{

    var solution = solver.Solve(_model);

}

Of these, only TimeLimit is actually respected.

My gurobi.lic file looks like:

CLOUDACCESSID=foo

CLOUDKEY=bar

CLOUDPOOL=baz

Thanks,

Jessica.

[OPTANO Team]

Hi,

I'll have a look at this issue.

As a quick qorkaround, you might want to place a new gurobi.lic file into the application folder.

I shall be taken primarily (instead of the gurobi.lic in gurobi's installation folder.)

When adding the gurobi nuget package, it should add such a file to your project.

Best,

jp

[OPTANO Team]

Hi,

I think the issue is related to the initialization of the GrbEnv(). Probably Gurobi looks for a license immediately on startup, finds it in the c:\gurobi\gurobi.lic file and then rejects the cloud credentials. I get a corresponding message on my system
"Gurobi.GRBException: Mixing different types of licence parameters is not allowed"

We will adapt the instantiation of GrbEnv and discuss whether to introduce a parameter that allows users to choose which license information should be taken from the GurobiSolver configuration (Cloud, ISV, File, etc.)

I will get back to you as soon as possible!
Greetings,
jp

[Jessica Wong]

That's not quite what I'm seeing, however. If I remove the license file completely, it still doesn't read the license fields in the GurobiConfiguration. It behaves the same as if they are unspecified, i.e. to use the limited license.

[OPTANO Team]

does gurobi read the license file in your local application folder at first?

[Jessica Wong]

So it did read the file once I put it there (there was no placeholder file). However I don't see any error about mixing licenses when supplying it both ways.

[Jessica Wong]

Another data point that might be useful:
When I use the config option LimitedLicenseUsage = OPTANO.Modeling.Optimization.Solver.Gurobi.LimitedLicenseUsage.Always :

When there is no license file available, I get an error (good). But when there is a license file available it uses the license.

[OPTANO Team]

Hi,

what Gurobi Version do you use?

The Gurobi 9 limited license is valid until End of year 2020.

Actually, When using Always,it Gurobi should never read its license from a file and never show an license error (at least, if the model is small enough).

No matter, if a license file is available.

We have put this ticket on the today's board. Probably it will be fixed in the next 24hrs.

Best,

jp

[OPTANO Team]

Hi,

we have fixed the issue and published a new Version to nuget (3.3.0).

The license check of gurobi is

Fix: License information parameters from GurobiSolverConfiguration were applied after the GRBEnv was already started. This causes an error.

• Additionally, some license parameters were not used, when initializing the GRBEnv.
  This has now been resolved for GurobiSolver 8.0 and later.
• Note: If you provide information for more than 1 license type (e.g. CloudServer + ComputeServer), the first complete license information will be used. License types are checked in the following order:
  

1. Check if LimitedLicenseUsage.Always
2. ISV License
3. Compute Server License
4. Cloud Server License
5. gurobi.lic file
6. Check if LimitedLicenseUsage.Fallback

• else: Abort with error

Best,

jp

[jya...@gmail.com]

I'm seeing new errors where Optano is trying to find a Gurobi license file when I'm trying to use the limited license. This is true even when I set the value LimitedLicenseUsage.Always in my Gurobi configuration. Could you see what might have changed? Perhaps the Gurobi limited license is no longer working? I wasn't checking for a while so I don't know when this broke. 

Jessica.

[OPTANO Team]

Hi,

could you provide a few more details:

* What version of gurobi would you like to use?

* What version of modeling do you use?

In general the Limited Keys time out and we keep on delivering new ones with new modeling versions - as long as Gurobi provides them. An update of modeling might just fix the issue, if your gurobi version is rather up to date.

Best,

jp

[jya...@gmail.com]

Using Optano 3.4.0.489 and Gurobi 9.0.2.24  

[OPTANO Team]

Hi,

I am not able to reproduce the issue.

I have create a blank dotnet project and added the package by using

> dotnet add package OPTANO.Modeling.Gurobi

which adds

* OPTANO.Modeling.Gurobi 9.0.2.24

* OPTANO.Modeling 3.3.0.473

The program.cs is just

using OPTANO.Modeling.Optimization.Solver.Gurobi;
using OPTANO.Modeling.Optimization.Solver.Gurobi900;
using System;

namespace isv_check
{
    class Program
    {
        static void Main(string[] args)
        {
            var solverConfig = new GurobiSolverConfiguration {LimitedLicenseUsage = LimitedLicenseUsage.Always};
            var solver = new GurobiSolver(solverConfig);
            Console.WriteLine(solver.ToString());
        }
    }
}

The output the is:

Using size-limited Gurobi license for Optano Modeling
Please visit https://www.gurobi.com/partners/optano to obtain an unlimited license.

OPTANO.Modeling.Optimization.Solver.Gurobi900.GurobiSolver

That just works!?

Would you kindly check the console output. Is the problem to large for the trial license?

Best,

jp