feat: use spack ci generate to setup build pipeline

Rather than having a single long build, we can split it up in different jobs with spack ci generate. This will be more resilient against failures. We can also run the builds inside a regular job instead of inside the container, and then only pull from the build cache once we build the container.

containers/jug/dev.Dockerfile

@@ -34,8 +34,6 @@ RUN echo "Part 1: regular spack install (as in containerize)"           \
  && if [ -n "$SPACK_CHERRYPICKS" ] ; then                               \
       git -C ${SPACK_ROOT} cherry-pick -n $SPACK_CHERRYPICKS ;          \
     fi                                                                  \
- && echo 'export LD_LIBRARY_PATH=/lib/x86_64-linux-gnu:$LD_LIBRARY_PATH'\ 
-        >> $SPACK_ROOT/share/setup-env.sh                               \
  && ln -s $SPACK_ROOT/share/spack/docker/entrypoint.bash                \
           /usr/sbin/docker-shell                                        \
  && ln -s $SPACK_ROOT/share/spack/docker/entrypoint.bash                \
@@ -43,18 +41,13 @@ RUN echo "Part 1: regular spack install (as in containerize)"           \
  && ln -s $SPACK_ROOT/share/spack/docker/entrypoint.bash                \
           /usr/sbin/spack-env                                           \
  && echo "Part 2: Set target to generic x86_64"                         \
- && echo "packages:" > $SPACK_ROOT/etc/spack/packages.yaml              \
- && echo "  all:" >> $SPACK_ROOT/etc/spack/packages.yaml                \
- && echo "    target: [x86_64]" >> $SPACK_ROOT/etc/spack/packages.yaml  \
+ && spack config --scope site add "packages:all:target:[x86_64]"        \
  && cat $SPACK_ROOT/etc/spack/packages.yaml                             \
  && echo "Part 3: Set config to allow use of more cores for builds"     \
  && echo "(and some other settings)"                                    \
- && echo "config:" > $SPACK_ROOT/etc/spack/config.yaml                  \
- && echo "  suppress_gpg_warnings: true"                                \
-        >> $SPACK_ROOT/etc/spack/config.yaml                            \
- && echo "  build_jobs: 64" >> $SPACK_ROOT/etc/spack/config.yaml        \
- && echo "  install_tree:" >> $SPACK_ROOT/etc/spack/config.yaml         \
- && echo "    root: /opt/software" >> $SPACK_ROOT/etc/spack/config.yaml \
+ && spack config --scope site add "config:suppress_gpg_warnings:true"   \
+ && spack config --scope site add "config:build_jobs:64"                \
+ && spack config --scope site add "config:install_tree:root:/opt/software" \
  && cat $SPACK_ROOT/etc/spack/config.yaml
 
 SHELL ["docker-shell"]