Automatically fix the nix hash

.github/workflows/checks.yml

@@ -23,11 +23,26 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
       - uses: cachix/install-nix-action@v24
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
       - name: "Building the nix file"
         run: |
             echo "If the job is failing with: \"hash mismatch in fixed-output derivation\""
             echo "Copy the hash after \"got:\" and replace \"npmDepsHash\" in \"flake-module.nix\" with the hash"
-            ! nix develop --command "exit 1" 2>&1 | grep "hash mismatch" -A2
+            ! nix develop --command "exit 1" 2>shell_output
+
+            # Filter the hash and then replace it in `flake-module.nix`
+            # This needs to run before the last step that may let's the job fail
+            cat shell_output | grep "got:" | sed "s/[ \t]*got:[ \t]*//" > hash
+            sed "s@npmDepsHash = \"[^\"]*\"@npmDepsHash = \"$(cat hash)\"@" -i flake-module.nix
+
+            ! cat shell_output | grep "hash mismatch" -A2
+
+      - uses: stefanzweifel/git-auto-commit-action@v5
+        if: always()
+        with:
+          add_options: '-u'
+          commit_message: Fix nix hash

flake-module.nix

@@ -8,7 +8,7 @@
     ...
   }: let
     # this change on each change of dependencies, unfortunately this hash not yet automatically updated from SRI of package.lock
-    npmDepsHash = "sha256-Nhbhe4R7NHN5E/emJlLLjbVRrvqwfO3I32Pg5La35AI=";
+    npmDepsHash = "sha256-CkQ9b8fWzuWkZoH+I+8htqaTjMHSXa8LPWltoU75/8Q=";
     ####
 
     # there is officia polkadot on nixpkgs, but it has no local rococo wasm to run