add routeros to overlay

pkgs/routeros/default.nix

@@ -0,0 +1,53 @@
+{
+  stdenv
+, python3
+, qemu
+, fetchzip
+, writeShellApplication
+}:
+let
+  chr-image = fetchzip {
+    url = "https://download.mikrotik.com/routeros/7.7/chr-7.7.img.zip";
+    hash = "sha256-utBQMUgNvl/UTG+GjnQShlGgVtHmRKtnhSTWW/JyeiY=";
+    curlOpts = "-L";
+  };
+  ros-exec-script = stdenv.mkDerivation {
+    name = "ros-exec-script";
+    src = ./.;
+    buildInputs = [python3];
+    buildPhase = ":";
+    installPhase = ''
+      mkdir -p $out/bin
+      cp ros-exec-script.py $out/bin/ros-exec-script
+      chmod +x $out/bin/ros-exec-script
+    '';
+  };
+  routeros = writeShellApplication {
+    name = "routeros";
+    runtimeInputs = [ qemu ros-exec-script ];
+    text = ''
+    RUNTIME_DIRECTORY=$1
+    test -d "$RUNTIME_DIRECTORY" || exit 1
+    ${qemu}/bin/qemu-system-x86_64 \
+      -M q35  \
+      -m 1024 \
+      -accel kvm \
+      -display none \
+      -daemonize \
+      -pidfile "$RUNTIME_DIRECTORY/pid" \
+      -serial "unix:$RUNTIME_DIRECTORY/console,server,nowait"\
+      -monitor "unix:$RUNTIME_DIRECTORY/monitor,server,nowait" \
+      -snapshot -drive file=${chr-image}/chr-7.7.img,format=raw,if=virtio \
+      -chardev "socket,path=$RUNTIME_DIRECTORY/qmp,server=on,wait=off,id=qga0" \
+      -device virtio-serial \
+      -device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0 \
+      -netdev socket,id=access,mcast=230.0.0.1:1234,localaddr=127.0.0.1 \
+      -device virtio-net-pci,disable-legacy=on,disable-modern=off,netdev=access,mac=ba:ad:1d:ea:11:02 \
+      -netdev socket,id=world,mcast=230.0.0.1:1236,localaddr=127.0.0.1 \
+      -device virtio-net-pci,disable-legacy=on,disable-modern=off,netdev=world,mac=ba:ad:1d:ea:11:01
+    ros-exec-script "$RUNTIME_DIRECTORY/qmp" ${./routeros.config}
+    '';
+  };
+in {
+  inherit routeros ros-exec-script;
+}