Claude Code Quick Reference

NixOS cluster configuration using flakes. Homelab infrastructure with Nomad/Consul orchestration.

Project Structure

├── common/
│   ├── global/                    # Applied to all hosts (backup, sops, users, etc.)
│   ├── minimal-node.nix           # Base (ssh, user, boot, impermanence)
│   ├── cluster-member.nix         # Consul agent + storage mounts (NFS/CIFS)
│   ├── nomad-worker.nix           # Nomad client (runs jobs) + Docker + NFS deps
│   ├── nomad-server.nix           # Enables Consul + Nomad server mode
│   ├── cluster-tools.nix          # Just CLI tools (nomad, wander, damon)
│   ├── workstation-node.nix       # Dev tools (wget, deploy-rs, docker, nix-ld)
│   ├── desktop-node.nix           # Hyprland + GUI environment
│   ├── nfs-services-server.nix    # NFS server + btrfs replication
│   └── nfs-services-standby.nix   # NFS standby + receive replication
├── hosts/                           # Host configs - check imports for roles
├── docs/
│   ├── CLUSTER_REVAMP.md    # Master plan for architecture changes
│   ├── MIGRATION_TODO.md    # Tracking checklist for migration
│   └── NFS_FAILOVER.md      # NFS failover procedures
└── services/            # Nomad job specs (.hcl files)

Current Architecture

Storage Mounts

/data/services - NFS from data-services.service.consul (check nfs-services-server.nix for primary)
/data/media - CIFS from fractal
/data/shared - CIFS from fractal

Cluster Roles (check hosts/*/default.nix for each host's imports)

Quorum: hosts importing nomad-server.nix (3 expected for consensus)
Workers: hosts importing nomad-worker.nix (run Nomad jobs)
NFS server: host importing nfs-services-server.nix (affinity for direct disk access like DBs)
Standby: hosts importing nfs-services-standby.nix (receive replication)

Config Architecture

Modular role-based configs (compose as needed):

minimal-node.nix - Base for all systems (SSH, user, boot, impermanence)
cluster-member.nix - Consul agent + shared storage mounts (no Nomad)
nomad-worker.nix - Nomad client to run jobs (requires cluster-member)
nomad-server.nix - Enables Consul + Nomad server mode (for quorum members)
cluster-tools.nix - Just CLI tools (no services)

Machine type configs (via flake profile):

workstation-node.nix - Dev tools (deploy-rs, docker, nix-ld, emulation)
desktop-node.nix - Extends workstation + Hyprland/GUI

Composition patterns:

Quorum member: cluster-member + nomad-worker + nomad-server
Worker only: cluster-member + nomad-worker
CLI only: cluster-member + cluster-tools (Consul agent, no Nomad service)
NFS primary: cluster-member + nomad-worker + nfs-services-server
Standalone: minimal-node only (no cluster membership)

Key insight: Profiles (workstation/desktop) don't imply cluster roles. Check imports for actual roles.

Key Patterns

NFS Server/Standby:

Primary: imports nfs-services-server.nix, sets standbys = [...]
Standby: imports nfs-services-standby.nix, sets replicationKeys = [...]
Replication: btrfs send/receive every 5min, incremental with fallback to full
Check host configs for current primary/standby assignments

Backups:

Kopia client on all nodes → Kopia server on fractal
Backs up /persist hourly via btrfs snapshot
Excludes: services@* and services-standby/services@* (replication snapshots)

Secrets:

SOPS for secrets, files in secrets/
Keys managed per-host

Migration Status

Phase 3 & 4: COMPLETE! GlusterFS removed, all services on NFS Next: Convert fractal to NixOS (deferred)

See docs/MIGRATION_TODO.md for detailed checklist.

Common Tasks

Deploy a host: deploy -s '.#hostname' Deploy all: deploy Check replication: Check NFS primary host, then ssh <primary> journalctl -u replicate-services-to-*.service -f NFS failover: See docs/NFS_FAILOVER.md Nomad jobs: services/*.hcl - service data stored at /data/services/<service-name>

Troubleshooting Hints

Replication errors with "empty stream": SSH key restricted to btrfs receive, can't run other commands
NFS split-brain protection: nfs-server checks Consul before starting
Btrfs snapshots: nested snapshots appear as empty dirs in parent snapshots
Kopia: uses temporary snapshot for consistency, doesn't back up nested subvolumes

Important Files

common/global/backup.nix - Kopia backup configuration
common/nfs-services-server.nix - NFS server role (check hosts for which imports this)
common/nfs-services-standby.nix - NFS standby role (check hosts for which imports this)
flake.nix - Host definitions, nixpkgs inputs

Auto-generated reference for Claude Code. Keep concise. Update when architecture changes.

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