build: compile OpenPMIx from source for MPI plugin in Dockerfile (#602)

* build: compile OpenPMIx from source for MPI plugin in Dockerfile

AlmaLinux 8 has no openpmix-devel package and distro pmix-devel is 2.x,
below pmix_min_version. Build OpenPMIx 5.0.3 during the builder stage
when BUILD_MPI_PLUGIN=1 so nightly and release tarballs include a functional
spur_mpi_pmix.so.

* build: add pkg-config/tar and download OpenPMIx tarball to file

Address Copilot review on PR #602: install pkgconf-pkg-config and tar
explicitly for the MPI plugin build, and fetch the OpenPMIx source
archive to a temp file before extraction.

Author: sgopinath1

Dockerfile

@@ -36,8 +36,11 @@ FROM chef AS builder
 ARG SPUR_GIT_SHA
 ARG SPUR_GIT_DIRTY
 ARG BUILD_MPI_PLUGIN=0
+ARG OPENPMIX_VERSION=5.0.3
 # BUILD_MPI_PLUGIN=1 links against libpmix and installs a functional spur_mpi_pmix.so
 # into dist artifacts. Default 0 builds the stub plugin (not copied to dist).
+# AlmaLinux 8 has no openpmix-devel RPM; distro pmix-devel (PowerTools) is PMIx 2.x.
+# Build OpenPMIx from source so the plugin meets pmix_min_version (4.1.0+).
 ENV SPUR_GIT_SHA=$SPUR_GIT_SHA
 ENV SPUR_GIT_DIRTY=$SPUR_GIT_DIRTY
 
@@ -52,8 +55,23 @@ RUN cargo build --release --locked \
     --bin spur-k8s-operator
 
 RUN if [ "$BUILD_MPI_PLUGIN" = "1" ]; then \
-        dnf install -y openpmix-devel && dnf clean all; \
+        dnf install -y dnf-plugins-core && \
+        dnf config-manager --set-enabled powertools && \
+        dnf install -y gcc-c++ flex bison python3 tar pkgconf-pkg-config libevent-devel hwloc-devel && \
+        curl -fsSL "https://github.com/openpmix/openpmix/releases/download/v${OPENPMIX_VERSION}/pmix-${OPENPMIX_VERSION}.tar.gz" \
+            -o "/tmp/pmix-${OPENPMIX_VERSION}.tar.gz" && \
+        tar xzf "/tmp/pmix-${OPENPMIX_VERSION}.tar.gz" -C /tmp && \
+        rm -f "/tmp/pmix-${OPENPMIX_VERSION}.tar.gz" && \
+        cd "/tmp/pmix-${OPENPMIX_VERSION}" && \
+        ./configure --prefix=/usr/local && \
+        make -j"$(nproc)" && make install && \
+        printf '%s\n' /usr/local/lib /usr/local/lib64 > /etc/ld.so.conf.d/openpmix.conf && \
+        ldconfig && \
+        rm -rf "/tmp/pmix-${OPENPMIX_VERSION}" && \
+        dnf clean all; \
     fi && \
+    cd /build && \
+    PKG_CONFIG_PATH="/usr/local/lib/pkgconfig:/usr/local/lib64/pkgconfig:${PKG_CONFIG_PATH:-}" \
     cargo build --release --locked -p spur-mpi-pmix
 
 RUN mkdir -p /dist/lib/spur && \