Some software being developed at our organisation is likely to include modified versions of Nextsrain, that will be provided as a service on private network.
I would like to be clear on what the GNU Affero General Public License v3.0 requires from us in these circumstances.
“When a modified version is used to provide a service over a network, the complete source code of the modified version must be made available.” So clearly, we must make the modified code available. Does this need to be completely open, as in a fully public repo, or does “available” here apply only to the network that the service is provided on?
“You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy” - So this means our software must also be published under the " GNU Affero General Public License v3.0"?
These are questions which are best answered by a lawyer familiar with software licensing and, crucially, the specifics of your situation. However, I’ll refer you to two things.
…requires the operator of a network server to provide the source code of the modified version running there to the users of that server. Therefore, public use of a modified version, on a publicly accessible server, gives the public access to the source code of the modified version.
Your private service on a private network would likely only need the source of modifications made available to the private users accessing it. (But again, IANAL.)
The GPL does not require you to release your modified version, or any part of it. You are free to make modifications and use them privately, without ever releasing them. This applies to organizations (including companies), too; an organization can make a modified version and use it internally without ever releasing it outside the organization.
But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program’s users, under the GPL.
So your private modified version likely does not have to be released (but if it was, then it would have to be released under the same license).