First crack at a GitHub Actions workflow

Author: jkachmar

.github/workflows/ghcup.yaml

@@ -0,0 +1,47 @@
+name: "`ghcup` image"
+
+on:
+  # FIXME: Remove this before merging!
+  pull_request: { branches: [ "master" ] }
+  push: { branches: [ "release" ] }
+
+env:
+  alpine_ver: "3.14"
+
+jobs:
+  build:
+    runs-on: "ubuntu-20.04"
+
+    strategy:
+      matrix:
+        ghc_ver: [ "8.10.7" ]
+        numeric: [ "gmp" ]
+
+    steps:
+      - name: "Check this repository out."
+        uses: "actions/checkout@v2"
+
+      - name: "Build `ghcup` image."
+        id: "build-ghcup-image"
+        run: |
+          image=$(
+            ./ghcup/builder.sh \
+              -a "${{ env.alpine_ver }}" \
+              -g "${{ matrix.ghc_ver }}" \
+              -n "${{ matrix.numeric }}" \
+            | tail -n 1
+          )
+          echo "::set-output name=image::${image}"
+
+      - name: "Push `ghcup` image to the GitHub Container Registry"
+        id: "push-ghcup-to-ghcr"
+        uses: "redhat-actions/push-to-registry@v2"
+        with:
+          image: "${{ steps.build-ghcup-image.outputs.image }}"
+          username: "${{ github.actor }}"
+          password: "${{ github.token }}"
+          registry: "ghcr.io/${{ github.repository_owner }}"
+
+      - name: "Print image URL."
+        run: |
+          echo "Image pushed to [ ${{ steps.push-ghcup-to-ghcr.outputs.registry-paths }} ]"

.gitignore

@@ -1 +1,2 @@
 .direnv
+tmp

ghc/builder.sh

@@ -21,6 +21,7 @@ alpine_ver="3.14"
 container="ghc"
 image="ghc"
 ghc_ver="8.10.7"
+
 # NOTE: The logic associated with this will have to change for GHC 9.x and up to
 # support the changes introduced with the switch to `ghc-bignum`.
 numeric="gmp"
@@ -33,7 +34,7 @@ usage="USAGE: $0
                   default: ${container}
     -g GHC_VER    override the numeric library GHC is built against; either 'gmp' or 'simple'
                   default: ${ghc_ver}
-    -i IMAGE      override the default image name
+    -i IMAGE      override the default image base name
                   default: ${image}
     -n NUMERIC    override the numeric library GHC is built against; either 'gmp' or 'simple'
                   default: ${numeric}"
@@ -172,10 +173,32 @@ buildah run "${container}" \
 buildah run "${container}" \
     rm -rf "/tmp/{build.mk,compile_ghc.sh,patches}"
 
+# Add `ghcup`'s bin directory to the container's `PATH`.
+#
+# NOTE: This little bit of indirection is needed to get the container's 'PATH',
+# since '$PATH' would be sourced from the host.
+cntr_path=$(buildah run "${container}" printenv PATH)
+buildah config \
+  --env PATH="${cntr_path}:/root/.ghcup/bin" \
+  "${container}"
+
 ################################################################################
 # Generate the final image.
 ################################################################################
 
+# NOTE: `buildah` uses `/var/tmp` (or $TMPDIR) as a staging area when assembling
+# images.
+#
+# On systems where `/var/tmp` is mounted as `tmpfs`, this can cause `buildah` to
+# run out of space.
+#
+# In this case, create some `./tmp` directory and use it with `TMPDIR=./tmp`
+# before running `buildah commit`.
+#
+# e.g. Uncomment the following:
+#
+# mkdir -p ./tmp
+# TMPDIR=./tmp \
 buildah \
     --signature-policy=./policy.json \
     commit --rm "${container}" "${image}"

ghcup/builder.sh

@@ -22,12 +22,12 @@ container="ghcup"
 image="ghcup"
 
 usage="USAGE: $0
-    -h           show this help text
+    -h            show this help text
     -a ALPINE_VER override the default Alpine version
                   default: ${alpine_ver}
-    -c CONTAINER override the default container name
-                 default: ${container}
-    -i IMAGE      override the default image name
+    -c CONTAINER  override the default container name
+                  default: ${container}
+    -i IMAGE      override the default image base name
                   default: ${image}"
 
 while getopts "a:c:i:h" opt; do
@@ -106,14 +106,23 @@ buildah run "${container}" \
 buildah run "${container}" \
     mv /tmp/"ghcup-${ghcup_version}" /usr/bin/ghcup
 
-# ...set it to be executable...
+# ...make it executable...
 buildah run "${container}" \
     chmod +x /usr/bin/ghcup
 
-# ...clean up any scripts.
+# ...and clean up any scripts.
 buildah run "${container}" \
     rm -rf /tmp/validate_checksum.sh
 
+# Add `ghcup`'s bin directory to the container's `PATH`.
+#
+# NOTE: This little bit of indirection is needed to get the container's 'PATH',
+# since '$PATH' would be sourced from the host.
+cntr_path=$(buildah run "${container}" printenv PATH)
+buildah config \
+  --env PATH="${cntr_path}:/root/.ghcup/bin" \
+  "${container}"
+
 ################################################################################
 # Generate the final image.
 ################################################################################

shell.nix

@@ -6,6 +6,7 @@ pkgs.mkShell {
     skopeo
 
     # Misc. other dependencies.
+    jq
     nixpkgs-fmt
     shellcheck
   ];