pyomo specify solver location

Question

Seems pretty simple but how do I point Pyomo to a locally-installed solver? I was able to get a solution from NEOS from my local computer, so I know the model is appropriately designed. Yesterday I installed the COIN-OR tarfile onto an Azure Ubuntu VM and want to run my model on that VM using Jupyter.

Here's what I have so far:

solvername='ipopt'
solverpath_folder='~/COIN-OR/bin/'
solverpath_exe='~/COIN-OR/bin/ipopt' 

solver=SolverFactory(solvername,executable=solverpath_exe)
instance = model.create_instance()
opt.solve(instance,solver) 

Error messages:

WARNING: DEPRECATED: Cannot call Model.create_instance() on a constructed
    model; returning a clone of the current model instance.
WARNING: Could not locate the 'ipopt' executable, which is required for solver
    ipopt

Answer 1

To get rid of the first warning you're seeing, you don't need the create_instance call when you're working with concrete models.

To address the second warning and your question, we recommend adding the directory containing the solver executables to your search path by modifying the PATH environment variable. If you don't want to modify your search path then I would try specifying the path to the executable without using ~/ as a shortcut to your home directory.