Use more complex activation wrapper and add workaround for deploy-rs#185

Author: notgne2

flake.nix

@@ -48,13 +48,14 @@
           activate = rec {
             custom =
               {
-                __functor = customSelf: base: activate:
-                  final.buildEnv {
-                    name = ("activatable-" + base.name);
-                    paths =
-                      [
-                        base
-                        (final.writeTextFile {
+              __functor = customSelf: base: activate:
+                base.overrideAttrs (oldAttrs: {
+                  name = "activatable-${base.name}";
+                  buildCommand = ''
+                    set -euo pipefail
+                    ${nixpkgs.lib.concatStringsSep "\n" (map (outputName:
+                      let
+                        activatePath = final.writeTextFile {
                           name = base.name + "-activate-path";
                           text = ''
                             #!${final.runtimeShell}
@@ -71,20 +72,39 @@
                             fi
                           '';
                           executable = true;
-                          destination = "/deploy-rs-activate";
-                        })
-                        (final.writeTextFile {
-                            name = base.name + "-activate-rs";
-                            text = ''
+                        };
+
+                        activateRs = final.writeTextFile {
+                          name = base.name + "-activate-rs";
+                          text = ''
                             #!${final.runtimeShell}
                             exec ${self.packages.${system}.default}/bin/activate "$@"
                           '';
                           executable = true;
-                          destination = "/activate-rs";
-                        })
-                      ];
-                  };
-              };
+                        };
+                      in (''
+                        ${final.coreutils}/bin/mkdir "''$${outputName}"
+
+                        echo "Linking activation components in ${outputName}"
+                        ${final.coreutils}/bin/ln -s "${activatePath}" "''$${outputName}/deploy-rs-activate"
+                        ${final.coreutils}/bin/ln -s "${activateRs}" "''$${outputName}/activate-rs"
+
+                        echo "Linking output contents of ${outputName}"
+                        ${final.findutils}/bin/find "${base.${outputName}}" -maxdepth 1 | while read -r file; do
+                          ${final.coreutils}/bin/ln -s "$file" "''$${outputName}/$(${final.coreutils}/bin/basename "$file")"
+                        done
+                      '' + nixpkgs.lib.optionalString
+                        (outputName == "out") ''
+                          # Workaround for https://github.com/serokell/deploy-rs/issues/185
+                          if [ -x "${base.${outputName}}/prepare-root" ]; then
+                            echo "Copying prepare-root"
+                            rm "$out/prepare-root" || :
+                            cp "${base.${outputName}}/prepare-root" "$out/prepare-root"
+                          fi
+                        '')) (base.outputs or [ "out" ]))}
+                  '';
+                });
+            };
 
             nixos = base:
               (custom // {