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nixfiles

My NixOS configuration and assorted other crap, powered by flakes. Clone to /etc/nixos.

CI checks ensure that code is formatted and passes linting. Run those locally with:

nix flake check
nix run .#fmt
nix run .#lint

See the documentation.

Overview

This is an opinionated config making assumptions which work for me but might not for you:

  • These are primarily single-user hosts, with me being that user. While security and availability are important, convenience takes priority.
  • Observability is good but there's no central graphing or alerting stack, every host has to run their own.
  • Databases should not be shared, each service has its own containerised instance. This means a single host may run several instances of the same database software, but that's an acceptable overhead.
  • Persistent docker volumes should be backed by bind-mounts to the filesystem.
  • For ZFS systems, wiping / on boot is good actually.

Everything in shared/default.nix is enabled on every host by default. Notable decisions are:

  • Every user gets a ~/tmp directory with files cleaned out after 7 days.
  • Automatic upgrades (including reboots if needed), automatic deletions of generations older than 30 days, and automatic garbage collection are all enabled.
  • Locale, timezone, and keyboard layout all set to UK / GB values (yes, even on servers).
  • Firewall and fail2ban are enabled, but pings are explicitly allowed.
  • SSH accepts pubkey auth only: no passwords.
  • Syncthing is enabled.

For monitoring and alerting specifically:

  • Prometheus, Grafana, and Alertmanager are all enabled by default (Alertmanager needs AWS credentials provided to actually send alerts).
  • The Node Exporter is enabled, along with a dashboard.
  • cAdvisor is enabled, along with a dashboard.

If using ZFS there are a few more things configured:

  • All pools are scrubbed monthly.
  • The auto-trim and auto-snapshot jobs are enabled (for pools which have those configured).
  • There's a Prometheus alert for pools in a state other than "online".

Everything else in shared/ is available to every host, but disabled by default.

Tools

Backups

Backups are managed by shared/restic-backups and uploaded to Backblaze B2 with restic.

List all the snapshots with:

nix run .#backups                                # all snapshots
nix run .#backups -- snapshots --host <hostname> # for a specific host
nix run .#backups -- snapshots --tag <tag>       # for a specific tag

Restore a snapshot to <restore-dir> with:

nix run .#backups restore <snapshot> [<restore-dir>]

If unspecified, the snapshot is restored to /tmp/restic-restore-<snapshot>.

Secrets

Secrets are managed with sops-nix. Create / edit secrets with:

nix run .#secrets                   # secrets.yaml for current host
nix run .#secrets <hostname>        # secrets.yaml for <hostname>
nix run .#secrets <hostname> <name> # <name>.yaml for <hostname>