From 94b4db41750a7b6846ba57f643cb05d8bf94e1cb Mon Sep 17 00:00:00 2001
From: pacien
Date: Mon, 14 Nov 2022 00:40:17 +0100
Subject: mkSandboxSystem: add tools and envVars option with printing

---
 example/flake.nix         | 13 +++++++++++++
 lib/mk-sandbox-system.nix | 20 +++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/example/flake.nix b/example/flake.nix
index 50931c6..17d15fc 100644
--- a/example/flake.nix
+++ b/example/flake.nix
@@ -50,6 +50,10 @@
     # By default, the VM is launched in the current console without a graphical
     # interface, dropping to a shell for the default dummy user within.
     #
+    # The binaries made available through the `tools` option and the
+    # environment variable set through the `envVars` option are printed when
+    # entering the shell.
+    #
     # The current working directory from which the Flake is run is mounted and
     # made available within the virtual machine in /mnt. The root filesystem
     # is ephemeral (written to a temporary file in /tmp).
@@ -64,6 +68,15 @@
       name = "sandbox";
       user = "dummy";
 
+      tools = with pkgs; [
+        postgresql
+        pgcli
+      ];
+
+      envVars = {
+        PGDATABASE = "app";
+      };
+
       config = {
         virtualisation.forwardPorts = [
           { from = "host"; host.port = 5432; guest.port = 5432; }  # postgres
diff --git a/lib/mk-sandbox-system.nix b/lib/mk-sandbox-system.nix
index a56bdab..b678399 100644
--- a/lib/mk-sandbox-system.nix
+++ b/lib/mk-sandbox-system.nix
@@ -3,11 +3,16 @@ flake:
 , name ? "sandbox"
 , user ? "dummy"
 , config ? { }
+, tools ? []
+, envVars ? { }
 , restrictNetwork ? true  # to be replaced with virtualisation.restrictNetwork
 , patchQemu9p ? false  # until qemu 7.2.0 becomes available in nixpkgs
 }:
 
-rec {
+let
+  shellLib = flake.lib.shell { inherit pkgs; };
+
+in rec {
 
   nixosConfigurations.${name} = pkgs.nixos ({ modulesPath, lib, pkgs, ... }: {
     imports = [
@@ -43,6 +48,19 @@ rec {
       '';
     };
 
+    environment = {
+      variables = envVars;
+      systemPackages = tools;
+
+      # TODO: also print a summary of the host mount points
+      # TODO: also print a summary of the forwarded ports
+      interactiveShellInit = lib.mkBefore ''
+        ${lib.optionalString (envVars != {}) (shellLib.printEnvVars envVars)}
+        ${lib.optionalString (tools != []) (shellLib.printBins tools)}
+        echo
+      '';
+    };
+
     virtualisation = {
       graphics = lib.mkDefault false;
       diskImage = lib.mkDefault "$TMP_DISK";
-- 
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