multi: using nix flake and upgrading lwk

The version of lwk has been raised to cli_0.5.1.
Change to use flake to use cli_0.5.1 in nix as well.
Using flake allows you to run nix develop instead of nix-shell.

Just uses the flake on nix shell.
For the nix-env addon users.

.github/workflows/ci.yml

@@ -47,17 +47,12 @@ jobs:
           key: nix-${{ hashFiles('packages.nix') }}
 
       - name: Install Nix
-        uses: cachix/install-nix-action@v20
+        uses: actions/checkout@v3
+      - uses: cachix/install-nix-action@v25
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
-
-      - name: "Import Nix store cache"
-        if: "steps.nix-cache.outputs.cache-hit == 'true'"
-        run: "nix-store --import < /tmp/nixcache"
-
-      - name: Run tests
-        run: nix-shell --run "make test-${{matrix.test-vector}}"
-
-      - name: "Export Nix store cache"
-        if: "steps.nix-cache.outputs.cache-hit != 'true'"
-        run: "nix-store --export $(find /nix/store -maxdepth 1 -name '*-*') > /tmp/nixcache"
+          extra_nix_config: |
+            trusted-public-keys = nix.casatta.it:HseKZh7436/vKXfZDBHbhr7wwAkzjLwY5BIq+OOrITg= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+            substituters = https://nix.casatta.it https://cache.nixos.org/
+      - uses: DeterminateSystems/magic-nix-cache-action@v2
+      - name: "test"
+        run: nix develop --command make test-${{matrix.test-vector}}

docs/setup_lwk.md

@@ -3,7 +3,7 @@
 **[Liquid Wallet Kit](https://github.com/Blockstream/lwk/tree/master)** is a collection of Rust crates for [Liquid](https://liquid.net) Wallets and is used for PeerSwap L-BTC swaps.  
 To set up `lwk` for PeerSwap, follow the steps here.  
 lwk is currently under development and changes are being made.  
-**peerswap has been tested only with [cli_0.3.0](https://github.com/Blockstream/lwk/tree/cli_0.3.0)**.
+**peerswap has been tested only with [cli_0.5.1](https://github.com/Blockstream/lwk/releases/tag/cli_0.5.1)**.
 
 ## wallet
 peerswap assumes a wallet with blinding-key set in singlesig to lwk.

flake.nix

@@ -0,0 +1,60 @@
+{
+  inputs = {
+    # Pinning to revision 755b915a158c9d588f08e9b08da9f7f3422070cc 
+    # - cln v24.05
+    # - lnd v0.18.0-beta
+    # - bitcoin v27.1
+    # - elements v23.2.1
+    nixpkgs.url = "github:NixOS/nixpkgs/755b915a158c9d588f08e9b08da9f7f3422070cc";
+    flake-utils.url = "github:numtide/flake-utils";
+    # blockstream-electrs: init at 0.4.1 #299761
+    # https://github.com/NixOS/nixpkgs/pull/299761/commits/680d27ad847801af781e0a99e4b87ed73965c69a
+    nixpkgs2.url = "github:NixOS/nixpkgs/680d27ad847801af781e0a99e4b87ed73965c69a";
+    # lwk: init at wasm_0.6.3 #14bac28
+    # https://github.com/Blockstream/lwk/releases/tag/wasm_0.6.3
+    lwk-flake = {
+      url = "github:blockstream/lwk/14bac284fe712dd6fdbbbe82bda179a2a236b2fa";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-utils.follows = "flake-utils";
+      };
+    };
+  };
+  outputs = { self, nixpkgs, nixpkgs2, flake-utils, lwk-flake }:
+    flake-utils.lib.eachDefaultSystem
+      (system:
+        let
+          pkgs = import nixpkgs {
+            system = system;
+          };
+          pkgs2 = import nixpkgs2 {
+            system = system;
+          };
+          blockstream-electrs = pkgs2.blockstream-electrs.overrideAttrs (oldAttrs: {
+            cargoBuildFlags = [ "--features liquid" "--bin electrs" ];
+          });
+          bitcoind = pkgs.bitcoind.overrideAttrs (attrs: {
+            meta = attrs.meta or { } // { priority = 0; };
+          });
+          lwk = lwk-flake.packages.${system}.bin;
+        in
+        with pkgs;
+        {
+          devShells.default = mkShell {
+            buildInputs = [
+              go_1_22
+              gotools
+              blockstream-electrs
+              bitcoind
+              elementsd
+              clightning
+              lnd
+              lwk
+            ];
+            # Cannot run the debugger without this
+            # see https://github.com/go-delve/delve/issues/3085
+            hardeningDisable = [ "all" ];
+          };
+        }
+      );
+}