ci(spack): validate simphony Spack install in pull requests (#339)

Add a dedicated Docker stage that installs `simphony` via Spack, and validate that install path in pull request CI.

## What changed

- add a `spack-base` / `spack-no-env` flow in `Dockerfile`
- install Spack in the image and configure shell startup to source `setup-env.sh`
- use the latest builtin Spack repo state plus `BNLNPPS/spack-packages`
- install `simphony` through Spack in two steps:
  - `spack install --only=dependencies simphony ...`
  - `spack install --reuse simphony`
- add `.github/workflows/build-pull-request-spack.yaml`
- run a PR-only CI job that builds the `spack-no-env` stage
- smoke-test the result by verifying that `simphony` is installed and its Spack prefix exists

## Why

This gives us a focused CI signal that the current `simphony` package recipe remains installable via Spack, without coupling that check to the existing development-image workflows.

## Notes

- the Spack Docker stage is intended for package validation, not for development
- the CI job uses Dockerfile defaults rather than maintaining a separate version matrix
- the Spack repo state is intentionally not pinned so CI can catch packaging regressions against current Spack metadata

Author: plexoos

.github/workflows/build-pull-request-spack.yaml

@@ -0,0 +1,40 @@
+name: Build Pull Request Spack
+
+on:
+  pull_request:
+    branches:
+      - '**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  spack-install:
+    runs-on: ubuntu-latest
+    env:
+      IMAGE_TAG: simphony-spack-ci:pr-${{ github.event.pull_request.number }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Define environment variables
+        run: |
+          REPO_OWNER=$(echo "${{ github.repository_owner }}" | tr '[:upper:]' '[:lower:]')
+          echo "SPACK_BUILDCACHE_MIRROR=oci://ghcr.io/${REPO_OWNER}/simphony-spack-buildcache" >> "$GITHUB_ENV"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build Spack install image and run smoke test
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          pull: true
+          target: spack-no-env
+          build-args: |
+            SPACK_BUILDCACHE_MIRROR=${{ env.SPACK_BUILDCACHE_MIRROR }}

Dockerfile

@@ -136,3 +136,30 @@ ENV NVIDIA_DRIVER_CAPABILITIES=graphics,compute,utility
 WORKDIR ${OPTICKS_HOME}
 
 SHELL ["/bin/bash", "-l", "-c"]
+
+
+FROM spack-base AS spack-no-env
+
+WORKDIR ${OPTICKS_HOME}
+
+# Intentionally track the latest Spack repo state in CI to catch packaging regressions.
+RUN spack repo update -b develop builtin
+RUN spack repo add https://github.com/BNLNPPS/spack-packages
+RUN spack mirror add --unsigned simphony-buildcache "${SPACK_BUILDCACHE_MIRROR}"
+RUN spack external find --not-buildable --path /usr/local/cuda cuda
+# Prefer dependency binaries when they exist, but let PR validation fall back to
+# source builds if the mirror lags behind the latest Spack package metadata.
+RUN spack install --only=dependencies --reuse --use-buildcache auto simphony ^geant4@${GEANT4_VERSION} ^optix-dev@${OPTIX_VERSION}
+RUN spack install --reuse --use-buildcache package:never,dependencies:auto simphony ^geant4@${GEANT4_VERSION} ^optix-dev@${OPTIX_VERSION}
+RUN spack clean -a && rm -rf /root/.cache
+# Once simphony is installed it can be loaded in the user environment
+# $ spack load simphony
+# $ spack load --sh simphony >> /etc/profile.d/z10_load_simphony_from_spack.sh
+RUN set -euo pipefail \
+ && spack find --format "{name}{@version} {/hash}" simphony \
+ && prefix="$(spack location -i simphony)" \
+ && echo "Installed prefix: $prefix" \
+ && test -d "$prefix" \
+ && (test -f "$prefix/.spack/spec.json" || test -f "$prefix/.spack/spec.yaml")
+
+FROM develop AS default