Allow Swap space to be set by default on servers with "spin provision"

[jaydrogers]

👉 Describe the problem

• Some hosts may not set swap space by default, which could lead to issues on low memory servers

👥 Problem evidence & reach

• https://discord.com/channels/910287105714954251/1366789787083608205
• https://x.com/jaydrogers/status/1917232937159811370

🥰 Describe the "impact" on users?

• If we can come up with sensible defaults, we could get rid of a lot of confusion when their server runs out of memory

🏆 How to solve this problem

Add sensible defaults for spin provision

• Perform the updates on the Ansible Spin Collection (https://github.com/serversideup/ansible-collection-spin)
• Automatically calculate swap space based on server resources
• Allow user to disable swap space all together
• Allow user to change swap settings with variables

🗣️ Further discussion

1. What "swapiness" settings should we have by default?
2. What calculation should we run to set the right amount of swap space by default (usually it's a caclulation of how much memory)

[magicyoda]

During provisioning only ?

• I could see this as a per-server setting defined in .spin.yml, provided as an optional setting without defaults.
• If swap already pre-exists on the host, resize it to match the desired value; if not, create it from scratch during provisioning.
• Resizing later would require the user to run a command on the server.

Anytime ?

• Allow a custom .env variable to define the actual swap file size which would be created/resized during any GHA deployment.
• Resizing could be done anytime 😊

Settings could be

• null (optional)
• 'auto' (= a bit more advanced implementation)
• '500M' or '8G' (or any size value)

'Auto' calculation could be

RAM Size	Recommended Swap (No Hibernation)
≤ 2 GB	2 × RAM
2–8 GB	= RAM
8–64 GB	At least 4 GB
> 64 GB	At least 4 GB

Sources:

• https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/storage_administration_guide/ch-swapspace

Or check the calculator:

• https://pickwicksoft.github.io/swapcalc/