Add dev shell environment (#1534)

* Add flake

* small fix

* Update contributing guide and clean flake

* Update CONTRIBUTING.md

Co-authored-by: Leigh McCulloch <[email protected]>

---------

Co-authored-by: Leigh McCulloch <[email protected]>

.gitignore

@@ -7,3 +7,4 @@ snapshot.json
 test_snapshots
 .vscode/settings.json
 .idea
+local.sh

CONTRIBUTING.md

@@ -14,6 +14,31 @@ changes quickly.
   * Clearly describe the issue including steps to reproduce if it is a bug.
 * Fork the repository on GitHub.
 
+## Setting up development environment
+
+There are 2 ways to being developing stellar-cli:
+
+### Installing all required dependencies 
+
+You may want to install all required dependencies locally. This includes installing `rustup`, `make`, `libudev`, `jq` from your package manager. After all dependencies are installed, you can start with running `make install` to build `stellar-cli` and install it! 
+
+### Using `nix`
+
+If you don't want to install necessary dependencies from above, you can run development shell using [nix](https://nixos.org/guides/how-nix-works/) (make sure to [install](https://nixos.org/download/) version above 2.20). After installing `nix`, simply run `nix develop` that will start new `bash` session in your current terminal. If you want to use different shell (e.g. `zsh`) you can run `nix develop -c zsh`
+
+This session will have:
+1. All required dependencies installed
+2. `stellar` alias (overwriting your existing `stellar` installed via cargo, if any)
+3. Configured auto-complete for the working git branch
+
+You can add extra configuration in your `local.sh` file (for example, if you want to export some extra variables for your devshell you can put following in your `local.sh`:
+```shell
+#!/usr/bin/env bash
+export STELLAR_NETWORK=testnet
+```
+Note that all of dependencies and configurations mentioned above is available only in your local development shell, not outside of it.
+
+
 ### Minor Changes
 
 #### Documentation

flake.nix

@@ -0,0 +1,43 @@
+{
+  description = "stellar-cli development shell";
+
+  inputs = {
+    nixpkgs.url      = "github:NixOS/nixpkgs/nixos-unstable";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    flake-utils.url  = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, rust-overlay, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+      in
+      with pkgs;
+      {
+        devShells.default = mkShell {
+          buildInputs = [
+            openssl
+            pkg-config
+            libudev-zero
+            jq
+            (rust-bin.stable.latest.default.override {
+              extensions = [ "rust-src" ];
+              targets = [ "wasm32-unknown-unknown" ];
+            })
+          ];
+          shellHook =
+          ''
+            echo "Using `nix --version`"
+            alias stellar="cargo run --bin stellar --"
+            [ -f ./local.sh ] && source ./local.sh
+            shell=$0
+            shell=`basename $SHELL`
+            source <(stellar completion --shell $shell)
+          '';
+        };
+      }
+    );
+}