Update instructions for Ramble's new package manager support

[linsword13]

Context

A major enhancement that allows Ramble to support different package managers has been merged to the develop branch (#535.) This is a breaking change and is slated for the next release (v0.6.0). In preparation for this upcoming release, here are the instructions for updating existing configs and object (applications and modifiers) definitions.

Update instructions

Update Ramble config (example)

• Add a variants section to specify the package manager to use.

  ramble:
  +  variants:
  +    package_manager: spack
  

• Update the spack package config section to the software section. Also change spack_spec to pkg_spec.

  - spack:
  + software:
      packages:
        gcc9:
  -       spack_spec: gcc@9.3.0 target=x86_64
  +       pkg_spec: gcc@9.3.0 target=x86_64
          compiler_spec: gcc@9.3.0
  

Update applications and modifiers definitions

This is only applicable if you have defined your own Ramble applications and/or modifiers.

• Update the base class from SpackApplication/SpackModifier to ExecutableApplication/BasicModifier. For directives that use spack_spec, change those to pkg_spec instead. Additionally for such package manager directives, a package_manager parameter can be specified to define the applicable package managers. Here is an example that contains these changes.

• If the application/modifier uses the <software_spec_name> variable to locate the package installation path, the reference should be updated to <software_spec_name>_path (example)

We are here to help!

Please let us know via the comments if you encounter issues or have questions. We are here to assist with the update.