devenv Environment

Gaius uses devenv for a Nix-based development environment that provides all system dependencies reproducibly.

Structure

devenv.nix is a pure service declaration file. It defines:

• Packages: System tools (kubectl, k9s, mdbook, etc.) provided by Nix
• Environment variables: DATABASE_URL, PGPORT, KUBECONFIG, etc.
• Process definitions: One-liner exec blocks pointing to scripts
• Dependency graphs: Process startup ordering via depends_on
• enterShell: Interactive shell setup (PATH, aliases, KUBECONFIG)

Key Design Rules

No Inline Bash

All process startup bash lives in scripts/processes/*.sh. The devenv.nix exec blocks are one-liners:

processes.gaius-engine = {
  exec = ''
    exec ${config.devenv.root}/scripts/processes/gaius-engine.sh
  '';
};

Nix Store Paths as Env Vars

When a script needs Nix-managed binaries, pass them as environment variables:

processes.nifi = {
  exec = ''
    export NIFI_PACKAGE="${pkgs.nifi}"
    exec ${config.devenv.root}/scripts/processes/nifi.sh
  '';
};

KUBECONFIG Handling

enterShell only runs for interactive shells. Process scripts must set KUBECONFIG unconditionally from $HOME:

export KUBECONFIG="$HOME/.config/kube/rke2.yaml"

Never use fallback syntax (${KUBECONFIG:-...}) — the system KUBECONFIG may point to a root-owned path.

Environment Variables

Nix-Managed Tools

kubectl and k9s are provided by Nix (not the system RKE2 binary). This ensures version consistency across environments.