Merge pull request #4 from COSIMA/add_readme

Add README.

README.md

@@ -0,0 +1,92 @@
+# COSIMA Spack Configuration
+
+This repository contains the spack configuration and the spack environments used
+by COSIMA to deploy software on gadi.
+
+## Installation instructions
+
+Clone this repository and its submodules to some appropriate location (e.g.,
+`/g/data/ik11/spack/0.20.1`):
+```bash
+$ git clone --recursive https://github.com/COSIMA/spack-config.git /g/data/ik11/spack/0.20.1
+```
+Next, create the python virtual environment:
+```bash
+$ cd /g/data/ik11/spack/0.20.1
+$ ./bootstrap_venv.sh
+```
+Finally, to use this spack installation one just needs to activate the python
+environment:
+```bash
+$  . /g/data/ik11/spack/0.20.1/venv/bin/activate
+$ which spack
+spack ()
+{ 
+    : this is a shell function from: /g/data/ik11/spack/0.20.1/spack/share/spack/setup-env.sh;
+    : the real spack script is here: /g/data/ik11/spack/0.20.1/spack/bin/spack;
+    _spack_shell_wrapper "$@";
+    return $?
+}
+```
+
+## Installing software
+
+It is recommended that all software be installed using spack
+environments. Currently two environments are provided (the names should be
+self-explanatory):
+1. `access-om3-devel`
+2. `common_tools_and_libraries`
+
+Installation of a spack environment is usually quite straightforward, but
+because this can be a CPU intensive operation and take quite some time, it is
+best to do this in parallel and to use an interactive job. 
+
+### Step-by-step instructions:
+
+ 1. Activate spack environment
+
+First activate the spack environment
+```bash
+$ spack env activate <env>
+```
+where `<env>` by the actual name of the environment.
+
+ 2. Download the sources
+
+As the compute nodes do not have internet access, one needs to download all the
+necessary sources from the login node. This is done using a spack mirror.
+```bash
+$ spack mirror create -d sources -a
+```
+Here `sources` is the name of a mirror that has already been configured.
+
+ 3. Submit interactive job
+
+This should not use more than a single node. Also, make sure to add `gdata/ik11`
+and `scratch/ik11` to the storage options.
+
+ 4. Install software
+
+Once the job has started, because it starts a completely new shell session, one
+needs to activate again both the python and the spack environments:
+```bash
+$  . /g/data/ik11/spack/0.20.1/venv/bin/activate
+$ spack env activate <env>
+```
+Then one can simply do
+```bash
+$ spack install 
+```
+In this case, although each individual build will use some level of parallelism,
+spack will proceed through the installation of the packages sequentially. To
+fully use parallelism one needs to tell spack to create a Makefile and use this
+to install the software:
+```bash
+$ spack env depfile -o Makefile
+$ make -j
+```
+
+In the end, all the packages should be available in
+`/g/data/ik11/spack/0.20.1/opt/linux-rocky8-cascadelake/` and the corresponding
+environment modules are installed under
+`/g/data/ik11/spack/0.20.1/share/modules/linux-rocky8-cascadelake/`.