add shell.nix file to define build environment

Signed-off-by: Jakub Sokołowski <jakub@status.im>

README.md

@@ -7,7 +7,6 @@ You can learn more about bonded curves and how Discover works [here](https://our
 ## Available Scripts
 
 This project is based on Embark v4.0.1, with a few things customised for React. 
-
 ```
 yarn run build:dev
 ```
@@ -15,9 +14,13 @@ or
 ```
 yarn run build:prod
 ```
-
 Builds the app into the `full-build` directory and creates the `app.zip` ready for use with ElasticBeanstalk.
 
+You can use the Nix shell defined in [`shell.nix`](shell.nix) for build environment:
+```
+nix-shell --pure
+```
+
 ## Deployed Contracts
 
 Ropsten (the first is `STT`, the Status Test Token):

shell.nix

@@ -0,0 +1,17 @@
+{ pkgs ? import <nixpkgs> {
+  config.permittedInsecurePackages = [ "nodejs-12.22.12" ];
+} }:
+
+pkgs.mkShell {
+  name = "discover-build";
+
+  buildInputs = with pkgs; [
+    git
+    zip
+    python2
+    nodejs-12_x
+    (yarn.override { nodejs = nodejs-12_x; })
+  ];
+
+  NODE_NO_WARNINGS = 1;
+}