Build NetCDF without DAP and HDF4: halve the Linux wheel

tools/devops/install-netcdf-manylinux.sh

@@ -2,12 +2,21 @@
 #
 # Install the NetCDF stack inside a manylinux_2_28 container, for cibuildwheel.
 #
-# EPEL provides the NetCDF C library and HDF5 for both x86_64 and aarch64, but
-# no package for the legacy C++4 API that ForeFire's DataBroker includes as
-# <netcdf>, so that one is built from source. Everything lands in /usr/local
-# where auditwheel can find it and vendor it into the wheel.
+# HDF5 comes from EPEL. The NetCDF C library and the C++4 API are both built
+# from source into /usr/local, where auditwheel finds them and vendors them
+# into the wheel.
+#
+# NetCDF C is built rather than installed from EPEL so that DAP and HDF4 can
+# be switched off. EPEL enables both, and auditwheel then has to vendor their
+# entire dependency closure: DAP pulls libcurl, which drags in OpenSSL,
+# Kerberos, LDAP, libssh and a dozen more, about 10 MB across 22 libraries
+# that ForeFire never calls. macOS avoids this only because the system
+# provides libcurl. HDF4 adds another 1.4 MB, and Homebrew's NetCDF does not
+# enable it, so turning it off here also makes the two platforms agree.
 set -euo pipefail
 
+NETCDF_C_VERSION="${NETCDF_C_VERSION:-4.9.3}"
+NETCDF_C_SHA256="a474149844e6144566673facf097fea253dc843c37bc0a7d3de047dc8adda5dd"
 NETCDF_CXX4_VERSION="${NETCDF_CXX4_VERSION:-4.3.1}"
 NETCDF_CXX4_SHA256="6a1189a181eed043b5859e15d5c080c30d0e107406fbb212c8fb9814e90f3445"
 PREFIX="${PREFIX:-/usr/local}"
@@ -17,35 +26,82 @@ if [[ -f "${PREFIX}/include/netcdf" ]]; then
     exit 0
 fi
 
-echo "::group::Installing NetCDF C library from EPEL"
+echo "::group::Installing HDF5 from EPEL"
 dnf install -y epel-release
-dnf install -y netcdf-devel hdf5-devel
+dnf install -y hdf5-devel
 echo "::endgroup::"
 
-echo "::group::Building netcdf-cxx4 ${NETCDF_CXX4_VERSION}"
 workdir="$(mktemp -d)"
 trap 'rm -rf "${workdir}"' EXIT
 cd "${workdir}"
 
-tarball="netcdf-cxx4-${NETCDF_CXX4_VERSION}.tar.gz"
-curl -fsSL -o "${tarball}" \
-    "https://downloads.unidata.ucar.edu/netcdf-cxx/${NETCDF_CXX4_VERSION}/${tarball}"
-echo "${NETCDF_CXX4_SHA256}  ${tarball}" | sha256sum --check --strict
+fetch() {
+    local url="$1" tarball="$2" sha="$3"
+    curl -fsSL -o "${tarball}" "${url}"
+    echo "${sha}  ${tarball}" | sha256sum --check --strict
+    tar xzf "${tarball}"
+}
+
+echo "::group::Building netcdf-c ${NETCDF_C_VERSION}"
+fetch "https://downloads.unidata.ucar.edu/netcdf-c/${NETCDF_C_VERSION}/netcdf-c-${NETCDF_C_VERSION}.tar.gz" \
+      "netcdf-c-${NETCDF_C_VERSION}.tar.gz" "${NETCDF_C_SHA256}"
+cd "netcdf-c-${NETCDF_C_VERSION}"
 
-tar xzf "${tarball}"
+# --disable-dap and --disable-byterange both have to go: byterange is a second
+# remote-access path that links libcurl on its own. --disable-hdf4 drops
+# libmfhdf, libdf, libjpeg and libtirpc. ForeFire reads local .nc and PGD
+# files, so none of these are reachable from it.
+./configure \
+    --prefix="${PREFIX}" \
+    --enable-shared \
+    --disable-static \
+    --disable-dap \
+    --disable-byterange \
+    --disable-hdf4 \
+    --disable-libxml2 \
+    --disable-examples \
+    --disable-testsets
+make -j "$(nproc)"
+make install
+ldconfig
+cd "${workdir}"
+echo "::endgroup::"
+
+echo "::group::Building netcdf-cxx4 ${NETCDF_CXX4_VERSION}"
+fetch "https://downloads.unidata.ucar.edu/netcdf-cxx/${NETCDF_CXX4_VERSION}/netcdf-cxx4-${NETCDF_CXX4_VERSION}.tar.gz" \
+      "netcdf-cxx4-${NETCDF_CXX4_VERSION}.tar.gz" "${NETCDF_CXX4_SHA256}"
 cd "netcdf-cxx4-${NETCDF_CXX4_VERSION}"
 
+# nc-config from the netcdf-c just installed has to win over anything else on
+# PATH, so that the C++ API links the DAP-free build.
+export PATH="${PREFIX}/bin:${PATH}"
+export PKG_CONFIG_PATH="${PREFIX}/lib:${PREFIX}/lib64:${PKG_CONFIG_PATH:-}"
+
 # Autotools rather than the bundled CMake build: netcdf-cxx4 4.3.1 declares
 # `cmake_minimum_required(VERSION 2.8.12)`, and CMake 4 refuses anything below
-# 3.5. configure picks up the EPEL NetCDF through nc-config.
+# 3.5. configure picks up the NetCDF built above through nc-config.
 ./configure \
     --prefix="${PREFIX}" \
     --enable-shared \
     --disable-static
-make -j "$(nproc)"
-make install
+
+# SUBDIRS is overridden to skip examples/. They call nc_set_log_level, which
+# netcdf-c only exports when built --enable-logging, so they fail to link
+# against our build. 4.3.1 has no --disable-examples. The library, all the
+# headers including the <netcdf> umbrella, and the pkg-config file are still
+# installed.
+make -j "$(nproc)" SUBDIRS=cxx4
+make install SUBDIRS=cxx4
 ldconfig
 echo "::endgroup::"
 
 echo "NetCDF C++4 installed:"
 ls -l "${PREFIX}"/lib*/libnetcdf_c++4.so* "${PREFIX}/include/netcdf"
+
+# Fail loudly here rather than shipping a wheel that quietly regained the
+# dependency this script exists to avoid.
+if ldd "${PREFIX}"/lib*/libnetcdf.so | grep -q libcurl; then
+    echo "ERROR: libnetcdf still links libcurl; DAP or byterange is enabled." >&2
+    exit 1
+fi
+echo "Confirmed: libnetcdf does not link libcurl."