Subject: Re: License LPGL and commercialization
To: psycopg@lists.postgresql.org
References: <ce175cbd83bc4258b1f2996fcccff75a@osfhealthcare.org>
From: Federico Di Gregorio <fog@dndg.it>
Organization: DNDG srl
Cc: "Hunt, Brian C." <Brian.C.Hunt@osfhealthcare.org>
Message-ID: <ada8ae26-3f7a-3f54-37bd-76f8ca67b015@dndg.it>
Date: Wed, 24 Feb 2021 17:13:38 +0100
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On 24/02/21 16:24, Hunt, Brian C. wrote:
> I have recently been told by outside council (lawyers) that our 
> organization is unable to use LGPL licensed packages in software we plan 
> to sell.
> 
> We have already built a web app using Python + Django.
> 
> Ticket:
> 
> #461 (Support use of pypgsql instead of psycopg) – Django 
> (djangoproject.com) <https://code.djangoproject.com/ticket/461>
> 
> Seems to suggest the purpose of the LGPL license is not to prevent the 
> intended use we have in mind (selling the web app to be hosted locally 
> at other organizations). Instead it is to prevent other from building 
> off the drivers and then selling those drivers.
> 
> Is that the case? Is our intended purpose within the license constraints 
> outlined? Can we receive written confirmation that our intended use 
> won’t come back to hurt us and we have permission? Or can we not use 
> your package in this way? We will be compliant with whatever outcome is 
> required. If we need to move away from Django (psycopg2) then we can do 
> that if needed.

Dear Brian,

you can use psycopg2 in a proprietary, closed-source application as long 
as you don't modify psycopg2 itself and allow your users to replace the 
current version of the psycopg2 module with a new one (this is usually 
not a problem, unless you want to pack everything in a single 
executable). There is the misconception that the LGPL will "contaminate" 
Python, then Django and from there your application but this is not the 
case: accessing psycopg2 API via Python from a proprietary module is 
perfectly fine - we don't consider it "linking".

federico