Set the system path to a fixed location.

nix/modules/environment.nix

@@ -8,10 +8,52 @@
     };
   };
 
-  config = {
+  config =
-    environment.etc."profile.d/system-manager-path.sh".source =
+    let
-      pkgs.writeShellScript "system-manager-path.sh" ''
+      pathDir = "/run/system-manager/sw";
-        export PATH=${lib.makeBinPath config.environment.systemPackages}:''${PATH}
+    in
+    {
+      environment.etc = {
+        "profile.d/system-manager-path.sh".source =
+          pkgs.writeText "system-manager-path.sh" ''
+            export PATH=${pathDir}/bin/:''${PATH}
+          '';
+
+        # TODO: figure out how to properly add fish support. We could start by
+        # looking at what NixOS and HM do to set up the fish env.
+        #"fish/conf.d/system-manager-path.fish".source =
+        #  pkgs.writeTextFile {
+        #    name = "system-manager-path.fish";
+        #    executable = true;
+        #    text = ''
+        #      set -gx PATH "${pathDir}/bin/" $PATH
+        #    '';
+        #  };
+      };
+
+      systemd.services.system-manager-path = {
+        enable = true;
+        description = "";
+        wantedBy = [ "system-manager.target" ];
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+        };
+        script =
+          let
+            pathDrv = pkgs.buildEnv {
+              name = "system-manager-path";
+              paths = config.environment.systemPackages;
+              pathsToLink = [ "/bin" ];
+            };
+          in
+          ''
+            mkdir --parents $(dirname "${pathDir}")
+            if [ -L "${pathDir}" ]; then
+              unlink "${pathDir}"
+            fi
+            ln --symbolic --force "${pathDrv}" "${pathDir}"
           '';
       };
+    };
 }

test/nix/modules/default.nix

@@ -50,7 +50,8 @@ let
 
           services.nginx.enable = false;
 
-          environment.etc = {
+          environment = {
+            etc = {
               foo_new = {
                 text = ''
                   This is just a test!
@@ -58,6 +59,11 @@ let
               };
             };
 
+            systemPackages = [
+              pkgs.fish
+            ];
+          };
+
           systemd.services = {
             new-service = {
               enable = true;
@@ -258,9 +264,14 @@ forEachUbuntuImage
               node1.succeed("/system-manager-profile/bin/activate 2>&1 | tee /tmp/output.log")
               node1.succeed("grep -vF 'ERROR' /tmp/output.log")
               node1.wait_for_unit("system-manager.target")
+              node1.wait_for_unit("system-manager-path.service")
 
               node1.succeed("bash --login -c 'realpath $(which rg) | grep -F ${hostPkgs.ripgrep}/bin/rg'")
               node1.succeed("bash --login -c 'realpath $(which fd) | grep -F ${hostPkgs.fd}/bin/fd'")
+
+              node1.succeed("${newConfig}/bin/activate 2>&1 | tee /tmp/output.log")
+              node1.succeed("grep -vF 'ERROR' /tmp/output.log")
+              node1.succeed("bash --login -c 'realpath $(which fish) | grep -F ${hostPkgs.fish}/bin/fish'")
             '';
           })
       ];