@mvnetbiz the standard way of doing this is overriding the package set to create a custom python installation with the version that you want. See for example https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/prospector/default.nix.

That is, for mysql_workbench.nix, you add something like

let
  py2 = python2.override {
    packageOverrides = self: super:
      bcrypt = super.bcrypt.overridePythonAttrs(oldAttrs: rec {
        version = "3.1.X";
        src = oldAttrs.src.override {
          inherit version;
          sha256 = "...";
        };
        disabled = false;
      };
    });
  };
in
  ...

Since it is deprecated it seems like it would make sense to keep the definition in the package that requires it, so it can be removed once it isn't needed any more, but this is used by at least 2 used packages, also the expression might deviate significantly from the new version, would that end up being too verbose keeping in a per-use override? Would it be better to add a separate pythonPackages.bcrypt_3_1, and use that in these packages?

Since it is deprecated it seems like it would make sense to keep the definition in the package that requires it, so it can be removed once it isn't needed any more, but this is used by at least 2 used packages, also the expression might deviate significantly from the new version, would that end up being too verbose keeping in a per-use override? Would it be better to add a separate pythonPackages.bcrypt_3_1, and use that in these packages?

I took about 10 mins and looked at usages of bcrypt throughout nixpkgs. In the applications that need it, bcrypt is always overridden to a version ~3.1.7 (e.g. home-assistant). I think this is probably the path that you should take. I wouldn't worry about long derivation overrides, most seem to be pretty short.

pinging maintainer of bcrypt @domenkozar

IMHO, in that example, it is bcrypt's reverse dependency (home-assistant) breaking compatibility with it, so it makes sense to override it there. The reason for this patch is that bcrypt itself, not it's user, is dropping compatibility with python < 3.6, so anything requiring bcrypt on python2 will have to use this version, so I thought it made sense to have a more general patch. I can make the PRs for mysql-workbench, syncthing-gtk, (poretools?) if this gets closed.

There are many modules defined this way in pkgs/top-level/python-packages.nix, at least the first 4 I looked at result from the same upstream dropping of old python version, this doesn't seem too atypical.

@drewrisinger that's only if it's a python application, if he still needs python2 to work, this is the correct method. We do it for packages such as numpy.

also, please disable python2Packages.trytond:

  Processing ./trytond-5.6.5-py2-none-any.whl
  ERROR: Package 'trytond' requires a different Python: 2.7.18 not in '>=3.5'

https://github.com/NixOS/nixpkgs/pull/97996
3 packages failed to build:
python27Packages.junos-eznc python27Packages.trackpy python27Packages.trytond

Should that be in the same PR? It's not caused by this branch, it fails to build on master too, just with:

error: bcrypt-3.2.0 not supported for interpreter python2.7
(use '--show-trace' to show detailed location information)

NVM I guess that makes sense if it's bcrypt related

@drewrisinger, thanks for the comments. python-modules/bcrypt/default.nix already has disabled from commit referenced in PR body

Looks like enabling this breaks python27Packages.[junos-eznc, trackpy] b/c it's semi-adding a new package.

https://github.com/NixOS/nixpkgs/pull/97996
2 packages failed to build:
python27Packages.junos-eznc python27Packages.trackpy

34 packages built:
mysql-workbench poretools python27Packages.Fabric python27Packages.ansible python27Packages.awkward python27Packages.bcrypt python27Packages.bkcharts python27Packages.docker python27Packages.drms python27Packages.duckdb python27Packages.flammkuchen python27Packages.flask-bcrypt python27Packages.imbalanced-learn python27Packages.ldaptor python27Packages.mapsplotlib python27Packages.moto python27Packages.ncclient python27Packages.pandas python27Packages.paramiko python27Packages.passlib python27Packages.privacyidea-ldap-proxy python27Packages.pwntools python27Packages.pysftp python27Packages.pytest-ansible python27Packages.robotframework-sshlibrary python27Packages.scp python27Packages.seaborn python27Packages.sshtunnel python27Packages.uproot python27Packages.uproot-methods python27Packages.vega_datasets python27Packages.vidstab python27Packages.yfinance syncthing-gtk

trackpy is marked broken, and I don't think this broke junos-eznc, the derivation just couldn't evaluate previously, with error: bcrypt-3.2.0 not supported for interpreter python2.7. It is broken for some other reason apparently.