Configurable boot and swap partitions

[asgeirn]

I've been running various versions of the 23.11 AMIs on t4g.micro instances and struggle with two issues:

• /boot fills up after a while due to the number of kernels
• Instance crashes in the midst of nixos-rebuild due to out of memory (micro has 1GB)

So: Would it be possible to specify the /boot partition size, as well as adding a swap partition?

The second can of course be worked around by adding a swap file (which I did) or adding a second EBS and partition it as swap.

[arianvp]

How i've been personally tackling deploying to t4g.micro is by doing the evaluation and building outside of the instance. And have the instance pull the build on startup.

Instead of setting the user data to a nix configuration: that is built locally on the instance; I set the user data to a shell script that downloads the already built nixos configuration:
e.g. set the user data of the instance to:

  user_data = base64encode(<<-EOF
  #!/usr/bin/env bash
  set -e
  nix build '${var.nix_store_path}' \
    --profile /nix/var/nix/profiles/system \
    --experimental-features 'nix-command' \
    --extra-substituters '${local.nix_substituter}' \
    --extra-trusted-public-keys '${local.nix_trusted_public_key}'
  /nix/var/nix/profiles/system/bin/switch-to-configuration switch
  EOF
  )

And in CI:

nix copy --to my-cache .#nixosConfigurations.myserver.config.system.build.toplevel

Or if you're doing push based deploys:

nixos-rebuild switch --target-host  <the-ip-of-the-instance>

[arianvp]

For the /boot problem I think we can try to make the /boot partition a bit larger. I'll look into it.

[asgeirn]

I was completely oblivious to the fact that you can remotely build configurations, I'll definitely look into this!