Reproducible-SW-environment-with-Spack.md

@@ -4,3 +4,100 @@ Clone and source spack  (you can skip the clone step if spack is already install
 git clone https://github.com/spack/spack.git -b v0.17.1 ~/spack
 source ~/spack/share/spack/setup-env.sh
 ```
+**NOTE**: it is crucial to fix the `spack` version to have the identical SW packages versions (different Spack versions will have different preferred versions of packages, .e.g Spack v0.17.1 will install cuda@11.5.0, while the current spack master will install cuda@11.6.1).
+
+The above command will clone Spack in the directory you have created beforehand (you can clone it in a different directory).
+
+# Generate a specific version of gcc:
+Now, we will install a specific compiler (e.g. `gcc@9.4.0`) using the default compiler available in the system employed.
+```
+spack install -j 32 gcc@9.4.0 
+```
+Then, we add the generated compiler to spack :
+```
+spack load gcc@9.4.0
+spack compiler find
+```
+Finally, we generate the definitive (the one we will use), by installing it again using itself as a seed:
+```
+spack install -j 32 gcc@9.4.0 %gcc@9.4.0
+```
+# Create a Spack environment for WSClean (+IDG)
+Clone the `schaap-spack` repo in the repos folder of spack:
+```
+git clone https://git.astron.nl/RD/schaap-spack.git ~/spack/var/spack/repos/schaap-spack
+```
+Create and activate a spack environment:
+```
+spack env create wsclean-940
+spack env activate wsclean-940 -p
+```
+This results in a ~/spack/var/spack/environments/gcc-940/spack.yaml file. **Fill it as follows (fill the field inside the angular brackets with the appropriate content**):
+
+```
+spack:
+  specs: [wsclean@3.0.1%gcc@9.4.0 ^idg+report@0.8.1]
+  view: true
+  repos:
+  - ~spack/var/spack/repos/schaap-spack
+  concretization: together
+ 
+  compilers:
+  - compiler:
+      spec: gcc@9.4.0
+      paths:
+        cc: ~/spack/opt/spack/<os_arch>/gcc-9.4.0/gcc-9.4.0-<hash>/bin/gcc
+        cxx: ~/spack/opt/spack/<os_arch>/gcc-9.4.0/gcc-9.4.0-<hash>/bin/g++
+        f77: ~/spack/opt/spack/<os_arch>/gcc-9.4.0/gcc-9.4.0-<hash>/bin/gfortran
+        fc: ~/spack/opt/spack/l<os_arch>/gcc-9.4.0/gcc-9.4.0-<hash>/bin/gfortran
+      flags: {}
+      operating_system: debian11
+      target: x86_64
+      modules: []
+      environment: {}
+      extra_rpaths: []
+ 
+  modules:
+    enable:
+    - tcl
+    tcl:
+      hash_length: 0
+      naming_scheme: ${COMPILERNAME}/${COMPILERVER}/${PACKAGE}/${VERSION}
+      all:
+        environment:
+          set:
+            '{name}_ROOT': '{prefix}'
+```
+
+`<os_arch>` can be something similar: `linux-debian11-zen2` or `linux-rhel7-cascadelake` depending on the OS version and architecture.
+
+`<hash>` it changes at each installation (it should be something like: `y3wfadv4z2odyqrlrljbd6tefvidx4gn`).
+
+Now, install the environment (for certain make-based packages like `ciftsio` you should remove the `-j 32` because it will throw an error):
+```
+spack install -j 32
+```
+Source again spack to add the new modules to `MODULEPATH` :
+```
+source ~/spack/share/spack/setup-env.sh 
+```
+You will be able to load wsclean with:
+```
+module load gcc/9.4.0/wsclean/3.0.1
+```
+Typically the other modules will not be available, use the following command to refresh them:
+```
+spack module tcl refresh --delete-tree -y
+```
+
+# Additional notes
+If the modules are not available or the names still contain the hash. Try to use:
+```
+module --ignore_cache av 
+```
+Sometimes, the default `module.yaml` file creates conflict. Remove it and update the modules:
+```
+rm ~/spack/etc/spack/defaults/modules.yaml
+spack module tcl refresh --delete-tree -y
+module --ignore_cache av
+```
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