Reproducable flutter app with flake

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As Flutter is a go-to way for building GUIs also for desktop, canonical even promotes it in their blog, I want to make exactly that reproducable/hermetic using nix!

But I only find ways on how two build a dev shell with flutter etc included s.t. i can run flutter build etc manually.
What I actually want is that my flake produces a binary output on its own. For example nix run github:owner/repo should also work for repos containing flutter projects, or nix build .#apk should produce an apk, if the flake has the corresponding package.

The problem I face when trying to build such a flake is that i cannot get the pub get dependencies.

Even something in the likes of

packages = rec {

          fetchDeps = pkgs.stdenv.mkDerivation {
            name = "fetchDeps";
            buildInputs = with pkgs; deps ++ [ wget  cacert ];
            src = frontend-dir;
            buildPhase = ''
              export HOME=$(mktemp -d)
              export DART_VM_OPTIONS="--root-certs-file=/etc/ssl/certs/ca-certificates.crt"
              flutter pub get -vv
            '';
            installPhase = ''
              mkdir -p $out
              cp -r $HOME/.pub-cache $out/.pub-cache
            '';
            outputHashAlgo = "sha256";
            outputHashMode = "recursive";
            outputHash = pkgs.lib.fakeHash;
          };

          apk = pkgs.stdenv.mkDerivation {
            name = "apk";
            buildInputs = with pkgs; deps ++ [ jdk17 android.androidsdk ];
            src = frontend-dir;
            ANDROID_SDK_ROOT = "${android.androidsdk}/libexec/android-sdk";
            configurePhase = ''
              export HOME=$(mktemp -d)
              cp ${fetchDeps}/.pub-cache $HOME/.pub-cache
              flutter pub get --offline
              yes | flutter doctor --android-licenses
            '';
            buildPhase = ''
              flutter doctor
              flutter build apk
            '';
            installPhase = ''
              mkdir -p $out
              cp -r build/app/outputs/flutter-apk/app-release.apk $out/app-release.apk
            '';
          };
#....

wont work, as dart throws CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate(handshake.cc:393)…

Is it actually the case that we cannot have reproducable flutter applications or is there something like pub2nix out there i dont know of?

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related: flutter: fetching dependencies via `dart pub get` results in TLS error if run in sandbox · Issue #307017 · NixOS/nixpkgs · GitHub

3

answered in the related github issue.

Is it actually the case that we cannot have reproducable flutter applications

we have (look at my answer in the issue)

or is there something like pub2nix out there i dont know of?

yeah that exists in nixpkgs. I don’t think you can use it directly from outside of nixpkgs, but buildDartApplication and buildFlutterApplication use it.

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