feat(devShell): Output a shell with packages of all the enabled services

doc/devshell.md

@@ -0,0 +1,17 @@
+# DevShell
+
+`services-flake` uses [mkShell](https://nixos.org/manual/nixpkgs/stable/#sec-pkgs-mkShell) function to provide a shell with packages of all the enabled services.
+
+```nix
+# Inside `perSystem`
+{
+  process-compose."my-pc" = { ... };
+  devShells.default = pkgs.mkShell {
+    inputsFrom = [
+      config.process-compose."my-pc".services.outputs.devShell;
+    ];
+    # ...
+  };
+}
+```
+

doc/guide.md

@@ -2,4 +2,5 @@
 # Guide
 
 - [[datadir]]#
+- [[devshell]]#
 - [[custom-service]]#

example/share-services/northwind/flake.nix

@@ -18,13 +18,14 @@
       ];
       flake.processComposeModules.default =
         import ./services.nix { inherit inputs; };
-      perSystem = { self', pkgs, lib, ... }: {
+      perSystem = { self', pkgs, config, lib, ... }: {
         process-compose."default" = { config, ... }: {
           imports = [
             inputs.services-flake.processComposeModules.default
             inputs.self.processComposeModules.default
           ];
         };
+        devShells.default = config.process-compose."default".services.outputs.devShell;
       };
     };
 }

example/share-services/pgweb/flake.nix

@@ -15,7 +15,7 @@
       imports = [
         inputs.process-compose-flake.flakeModule
       ];
-      perSystem = { self', pkgs, lib, ... }: {
+      perSystem = { self', pkgs, config, lib, ... }: {
         process-compose."default" = { config, ... }: {
           imports = [
             inputs.services-flake.processComposeModules.default
@@ -32,6 +32,7 @@
             environment.PGWEB_DATABASE_URL = config.services.postgres.northwind.connectionURI { dbName = "sample"; };
           };
         };
+        devShells.default = config.process-compose."default".services.outputs.devShell;
       };
     };
 }

example/simple/flake.nix

@@ -16,7 +16,7 @@
       imports = [
         inputs.process-compose-flake.flakeModule
       ];
-      perSystem = { self', pkgs, lib, ... }: {
+      perSystem = { self', pkgs, config, lib, ... }: {
         # `process-compose.foo` will add a flake package output called "foo".
         # Therefore, this will add a default package that you can build using
         # `nix build` and run using `nix run`.
@@ -61,6 +61,9 @@
           };
 
         devShells.default = pkgs.mkShell {
+          inputsFrom = [
+            config.process-compose."default".services.outputs.devShell
+          ];
           nativeBuildInputs = [ pkgs.just ];
         };
       };

nix/services/default.nix

@@ -1,3 +1,4 @@
+{ pkgs, lib, config, ... }:
 let
   inherit (import ../lib.nix) multiService;
 in
@@ -24,4 +25,30 @@ in
     ./searxng.nix
     ./tika.nix
   ];
+
+  options.services.outputs.devShell = lib.mkOption {
+    type = lib.types.package;
+    readOnly = true;
+    description = ''
+      The devShell that aggregates packages from all the enabled services.
+    '';
+  };
+
+  config = {
+    services.outputs.devShell = pkgs.mkShell {
+      packages =
+        lib.pipe config.services [
+          # `outputs` is a reserved attribute set and is not the name of a service.
+          (lib.filterAttrs (n: _: n != "outputs"))
+          # Flatten services attrset
+          #
+          # Example:
+          # Input = { mysql."m1" = <cfg1>; mysql."m2" = <cfg2>; redis."r1" = <cfg3>; }
+          # Output = [ <cfg1> <cfg2> <cfg3> ]
+          (lib.foldlAttrs (acc: _: v: (lib.attrValues v) ++ acc) [ ])
+          (lib.filter (service: service.enable))
+          (map (service: service.package))
+        ];
+    };
+  };
 }