Add shell script that builds dune and makes tarball

This makes it easier to test the binary distro offline since the tarball
has the same logic as the release github action (which now just runs the
script). This also makes it more reliable to test the build and
packaging process since the script can be run from a test setting, so
this change also introduces a github action that runs such a test.

Signed-off-by: Stephen Sherratt <stephen@sherra.tt>

Author: gridbugs

.github/workflows/build.yml

@@ -25,13 +25,8 @@ jobs:
       - run: echo NAME=dune-${{ github.ref_name }}-${{ matrix.name }} >> $GITHUB_ENV
       - uses: actions/checkout@v4
       - uses: cachix/install-nix-action@v31
-      - name: Build dune
-        run: nix build ${{ matrix.output }}
-      - name: Create dune tarball
-        run: |
-          cp -rL result $NAME
-          chmod -R u+w $NAME
-          tar czf $NAME.tar.gz $NAME
+      - name: Build the binary distro and package it as a tarball
+      - run: ./make_tarball.sh $NAME ${{ matrix.output }}
       - uses: ncipollo/release-action@v1
         with:
           allowUpdates: true

.github/workflows/test.yml

@@ -0,0 +1,51 @@
+name: test
+on: [push, pull_request]
+jobs:
+
+  test-make-tarball:
+    name: "Test that we can build the binary distro and package it as a tarball"
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+          - os: macos-13
+            name: x86_64-apple-darwin
+            output: .#dune.dynamic
+          - os: macos-14
+            name: aarch64-apple-darwin
+            output: .#dune.dynamic
+          - os: ubuntu-latest
+            name: x86_64-unknown-linux-musl
+            output: .#dune.static
+    steps:
+      - run: echo NAME=dune-${{ matrix.name }} >> $GITHUB_ENV
+      - uses: actions/checkout@v4
+      - if: matrix.os == 'ubuntu-latest'
+        name: "Install shells on ubuntu"
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y zsh fish
+      - if: matrix.os != 'ubuntu-latest'
+        name: "Install shells on macos"
+        run: brew install fish
+      - uses: cachix/install-nix-action@v31
+      - name: "Build the binary distro and package it as a tarball"
+        run: ./make_tarball.sh $NAME ${{ matrix.output }}
+      - name: "Test that we can extract the tarball and run the env scripts and dune executable"
+        run: |
+          tar xf $NAME.tar.gz
+          bash -c "source $NAME/share/dune/env/env.bash; __dune_env $PWD/$NAME; dune --version"
+          zsh -c "source $NAME/share/dune/env/env.zsh; __dune_env $PWD/$NAME; dune --version"
+          fish -c "source $NAME/share/dune/env/env.fish; __dune_env $PWD/$NAME; dune --version"
+
+  test-make-tarball-shellcheck:
+    name: "Run shellcheck on the build script"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: "Install shellcheck"
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y shellcheck
+      - name: "Run shellcheck on the build script"
+        run: shellcheck make_tarball.sh

.gitignore

@@ -1 +1,2 @@
 result
+*.tar.gz

make_tarball.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+set -eu
+
+if [ "$#" -ne "2" ]; then
+    echo "Usage: $0 NAME TARGET"
+    echo
+    echo "Creates a file NAME.tar.gz containing the dune binary distro."
+    echo "TARGET is the nix target that gets built. It should be one of:"
+    echo "  - .#dune.dynamic (builds a dynamically-linked dune executable)"
+    echo "  - .#dune.static (builds a statically-linked dune executable)"
+    exit 1
+fi
+
+NAME="$1"
+TARGET="$2"
+
+set -x
+
+tmp_dir="$(mktemp -d)"
+trap 'rm -rf "$tmp_dir"' EXIT
+nix build "$TARGET"
+cp -rL result "$tmp_dir/$NAME"
+chmod -R u+w "$tmp_dir/$NAME"
+pushd "$tmp_dir"
+tar czf "$NAME.tar.gz" "$NAME"
+popd
+mv "$tmp_dir/$NAME.tar.gz" .