Enable Slurm REST API

[rkilpadi]

Description

• Added Chef script to enable slurmrestd on a head node.
• Configured slurm.conf to enable JWT authentication.
• Automated JWT token generation.
• Configured nginx to allow HTTPS calls to the slurm REST API.
• Added Slurm REST API custom script to pcluster manager.

How Has This Been Tested?

• Manually created clusters and ran curl commands from my local machine.

References

• Added a tutorial on how to enable custom script and test cluster creation.
• https://slurm.schedmd.com/rest_api.html

Work in Progress

• slurmdb calls to api do not work, but this is not needed for job submission.
• Still need to add support for different OSes (currently only works on alinux).

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[tmscarla]

Leave some comments, mostly clarifying questions.

Suggestion: in this PR you are adding files (nginx, chef and bash script), enhancing documentation and modifying a frontend React component. These changes could have been separated into multiple micro-commits.

Small, self-contained commits are easier to review, and in the context of a PR they tell a story of incremental changes. This can be really useful, drastically reducing the time spent in diving deep into the code in the next months, years, decades... :)