Hardcoded PREFIX in Slurm and Munge builds generate invalid paths

[jedel1043]

Setting prefix=/ at build time for Slurm generates incorrect paths that are baked at build time by Slurm. Examples:

Setting both LibPrefix and AuthInfo serves as a workaround, but it would be good to see if we can patch this to have correct default values.

[NucciTheBoss]

Unfortunately this is a limitation with the autotools plugin that I have run up against multiple times, especially when working with C-based code bases like Apache httpd and nginx. Many programs will bake the prefix into the source code during configuration and use those as the default paths if there's no additional configuration.

For example, if I didn't set the prefix, Slurm would likely bake in the path /root/parts/slurm/install/lib/slurm. httpd does something similar in the Ondemand snap, but I fix it by using a wrapper to point directly to the paths I want it to find. I see us having two possible solutions here:

1. Set the munged socket path and plugin path at configure time. Slurm has quite a few configure options. I do something like this for nginx.
2. During snap installation, auto-generate a slurm.conf file that sets the socket and plugin path to the correct locations. We can just do this in the install hook. I do something like this with the Ondemand snap.

Best bet is to probably first start with option 1 and then try option 2 if those configuration options are not available with the configure script.

[jedel1043]

Found another one

[NucciTheBoss]

The mungekey issue will be fixed in #14 by including a wrapper (or configure change) to point to the correct directory.

Regarding the Slurm location issues, I did not find an option that enables me to set specific values at configure time before building Slurm. Easiest fix here is to just autogenerate those slurm.conf options in the install hook, and then have some complimenting documentation that indicates why we generate those options automatically and why you're strongly discouraged from changing them.

[NucciTheBoss]

#18 slightly addresses this issue specifically with the munge key location and plugin dir, but there's still likely merits to automatically generating a basic slurm.conf file that includes info on how to configure munge. If a site isn't using configless mode, it would be good for us to already have set for where to look for the munged socket.

mungekey likely just requires a wrapper that points to the correct location.

[NucciTheBoss]

Actually, we can tell Slurm where to look by default for the munged service socket by using the --with-munge-socket configure option when building Slurm.

[NucciTheBoss]

This issue is fixed by #24 as Slurm is now able to find to the PluginDir and the munge key file without additional configuration - requires extra settings in the configure script - and we have a path forward for fixing the munge key command by fleshing out the configuration API for munge in #14