Merge pull request #1135 from LeastAuthority/3808.py3-nixos

Support Py3 on NixOS 21.05

Fixes: ticket:3808

.circleci/config.yml

@@ -42,6 +42,9 @@ workflows:
       - "nixos-19-09":
           {}
 
+      - "nixos-21-05":
+          {}
+
       # Test against PyPy 2.7
       - "pypy27-buster":
           {}
@@ -438,8 +441,7 @@ jobs:
         image: "tahoelafsci/fedora:29-py"
         user: "nobody"
 
-
-  nixos-19-09:
+  nixos-19-09: &NIXOS
     docker:
       # Run in a highly Nix-capable environment.
       - <<: *DOCKERHUB_AUTH
@@ -447,6 +449,7 @@ jobs:
 
     environment:
       NIX_PATH: "nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-19.09-small.tar.gz"
+      SOURCE: "nix/"
 
     steps:
       - "checkout"
@@ -463,7 +466,17 @@ jobs:
             # build a couple simple little dependencies that don't take
             # advantage of multiple cores and we get a little speedup by doing
             # them in parallel.
-            nix-build --cores 3 --max-jobs 2 nix/
+            nix-build --cores 3 --max-jobs 2 "$SOURCE"
+
+  nixos-21-05:
+    <<: *NIXOS
+
+    environment:
+      # Note this doesn't look more similar to the 19.09 NIX_PATH URL because
+      # there was some internal shuffling by the NixOS project about how they
+      # publish stable revisions.
+      NIX_PATH: "nixpkgs=https://github.com/NixOS/nixpkgs/archive/d32b07e6df276d78e3640eb43882b80c9b2b3459.tar.gz"
+      SOURCE: "nix/py3.nix"
 
   typechecks:
     docker:

newsfragments/3808.installation

@@ -0,0 +1 @@
+Tahoe-LAFS now supports running on NixOS 21.05 with Python 3.

nix/overlays.nix

@@ -2,25 +2,32 @@ self: super: {
   python27 = super.python27.override {
     packageOverrides = python-self: python-super: {
       # eliot is not part of nixpkgs at all at this time.
-      eliot = python-self.callPackage ./eliot.nix { };
+      eliot = python-self.pythonPackages.callPackage ./eliot.nix { };
 
       # NixOS autobahn package has trollius as a dependency, although
       # it is optional. Trollius is unmaintained and fails on CI.
-      autobahn = python-super.callPackage ./autobahn.nix { };
+      autobahn = python-super.pythonPackages.callPackage ./autobahn.nix { };
 
       # Porting to Python 3 is greatly aided by the future package.  A
       # slightly newer version than appears in nixos 19.09 is helpful.
-      future = python-super.callPackage ./future.nix { };
+      future = python-super.pythonPackages.callPackage ./future.nix { };
 
       # Need version of pyutil that supports Python 3. The version in 19.09
       # is too old.
-      pyutil = python-super.callPackage ./pyutil.nix { };
+      pyutil = python-super.pythonPackages.callPackage ./pyutil.nix { };
 
       # Need a newer version of Twisted, too.
-      twisted = python-super.callPackage ./twisted.nix { };
+      twisted = python-super.pythonPackages.callPackage ./twisted.nix { };
 
       # collections-extended is not part of nixpkgs at this time.
-      collections-extended = python-super.callPackage ./collections-extended.nix { };
+      collections-extended = python-super.pythonPackages.callPackage ./collections-extended.nix { };
+    };
+  };
+
+  python39 = super.python39.override {
+    packageOverrides = python-self: python-super: {
+      # collections-extended is not part of nixpkgs at this time.
+      collections-extended = python-super.pythonPackages.callPackage ./collections-extended.nix { };
     };
   };
 }

nix/py3.nix

@@ -0,0 +1,7 @@
+# This is the main entrypoint for the Tahoe-LAFS derivation.
+{ pkgs ? import <nixpkgs> { } }:
+# Add our Python packages to nixpkgs to simplify the expression for the
+# Tahoe-LAFS derivation.
+let pkgs' = pkgs.extend (import ./overlays.nix);
+# Evaluate the expression for our Tahoe-LAFS derivation.
+in pkgs'.python39.pkgs.callPackage ./tahoe-lafs.nix { }