add nix-instantiate

content/nixos/nix-instantiate.md

@@ -0,0 +1,59 @@
+---
+title: "nix-instantiate"
+date: 2018-12-05T19:09:36+02:00
+draft: true
+tags:
+- NixOS
+- Ansible
+- Terraform
+summary: >
+  a tool to create your JSON generator.
+---
+
+# nix-instantiate
+
+I like NixOS and the way modules work.
+I miss it when I do tasks in other languages,
+which have less power than NixOS, for example
+[Ansible](https://www.ansible.com) and [Terraform](https://www.terraform.io).
+
+Luckily all these tools can be configured via JSON,
+and Nix can easily create JSON.
+The tool go to tool for that job is
+[nix-instantiate](https://nixos.org/nix/manual/#sec-nix-instantiate)
+which every NixOS has installed (yeye!).
+
+## First tests
+
+Lets look what `nix-instantiate` does.
+
+We create a file `test1.nix`
+
+```nix
+# file test1.nix
+rec {
+  x = "hallo";
+  y = x;
+}
+```
+
+and than we run `nix-instantiate` to render json
+
+```sh
+$> nix-instantiate --eval --json --strict test1.nix | jq
+
+{
+  "x": "hallo",
+  "y": "hallo"
+}
+```
+
+Nice! this is expected because it is an example from 
+[the documentation](https://nixos.org/nix/manual/#sec-nix-instantiate).
+
+## Modules for the win
+
+Modules are one of the things that make NixOS really awesome.
+So lets us them in combination with `nix-instantiate`!
+
+... todo write more