Why not load shellHook?

[borski]

"Note: shellHook will not be loaded."

Is there a specific reason for this, or is it just an unsupported feature at the moment? If it's just an unsupported feature at the moment, you may have a PR coming your way. :)

[joshbode]

I think I excluded it because the hooks are bash-specific (?) and they broke ZSH, but I'm open to a PR if that's not the case (or we can fix the breakage)

[borski]

I ended up making it work... in my mise.toml:

[env]
_.nix = {}
_.source = ".mise-nix/scripts/run-nix-shellhook.sh"

[plugins]
nix = 'https://github.com/joshbode/mise-nix'

And then .mise-nix/scripts/run-nix-shellhook.sh looks like:

  #!/usr/bin/env bash
  # Mise + Nix integration script
  # Replicates nix-direnv's use_flake functionality for mise
  # 
  # Usage in mise.toml:
  #   [env]
  #   _.nix = {}
  #   _.source = ".mise-nix/scripts/run-nix-shellhook.sh"

  PROJECT_ROOT="${MISE_PROJECT_ROOT:-$(pwd)}"
  CACHE_DIR="${PROJECT_ROOT}/.mise-nix"
  ENV_CACHE="${CACHE_DIR}/env.sh"

  mkdir -p "$CACHE_DIR"

  # Check if we need to regenerate the environment cache
  need_update=0
  if [ ! -f "$ENV_CACHE" ]; then
    need_update=1
  elif [ "${PROJECT_ROOT}/shell.nix" -nt "$ENV_CACHE" ] || \
       [ "${PROJECT_ROOT}/flake.nix" -nt "$ENV_CACHE" ] || \
       [ "${PROJECT_ROOT}/flake.lock" -nt "$ENV_CACHE" ]; then
    need_update=1
  fi

  if [ "$need_update" -eq 1 ]; then
    # Use nix print-dev-env with --profile
    # The --profile flag creates a GC root so the environment doesn't get garbage collected
    SYSTEM=$(nix eval --impure --raw --expr 'builtins.currentSystem' 2>/dev/null)
    nix print-dev-env \
      --extra-experimental-features "nix-command flakes" \
      --profile "${CACHE_DIR}/profile" \
      ".#devShells.${SYSTEM}.default" \
      > "$ENV_CACHE" 2>/dev/null
  fi

  # Execute the cached environment (nix print-dev-env generates bash 4+ code)
  # This runs the shellHook commands (like initdb) and exports the variables
  if [ -f "$ENV_CACHE" ] && [ -s "$ENV_CACHE" ]; then
    # Find bash 4.0+ that supports ;& syntax (required by nix print-dev-env)
    # Check nix store first, then common installation locations
    BASH_BIN=""
    for bash_path in /nix/store/*/bin/bash /usr/local/bin/bash /opt/homebrew/bin/bash; do
      if [ -x "$bash_path" ]; then
        bash_version=$("$bash_path" --version 2>/dev/null | head -1 | grep -oE '[0-9]+\.[0-9]+' | head -1)
        bash_major=$(echo "$bash_version" | cut -d. -f1)
        if [ "$bash_major" -ge 4 ]; then
          BASH_BIN="$bash_path"
          break
        fi
      fi
    done

    # Fallback to system bash (will likely fail on macOS due to bash 3.2)
    [ -z "$BASH_BIN" ] && BASH_BIN="/bin/bash"

    # Run env.sh in bash subprocess to execute shellHook (like initdb)
    # File operations (database creation) persist after subprocess exits
    $BASH_BIN -c "source '$ENV_CACHE'" >/dev/null 2>&1 || true

    # Extract environment variables to current shell
    eval "$($BASH_BIN -c "source '$ENV_CACHE' >/dev/null 2>&1 && export -p" || true)"
  fi

I actually have it set up to pull that script from a gist in case I ever change it, but it would be better to have it integrated into mise-nix directly, to be fair.

[joshbode]

Thanks - I'll take a look at this!

I recall now why I didn't implement shellHook loading in the plugin:

1. It is very difficult to clean up whatever functions/variables were set in the shellHook - i.e. when you cd out of a project, we can't really reset the environment to undo the shellHook (unlike environment variables which mise automatically manages).

2. It seemed to be very difficult to reliably source/eval from within the Mise hooks - although, you can actually just print the shellHook to stdout in the hook and it will be evaluated by your shell - I'm not sure if this is intended, but in any case I had a number of bugs from this (especially when using mise in non-interactive settings).

[joshbode]

note: the shellHook is exported as a variable by the plugin, so if you want to quickly utilise it on-demand, you can just run:

$ eval "${shellHook}"

[borski]

Well, for what it's worth, I based my script off of what nix-direnv does under the hood for use flake: https://github.com/nix-community/nix-direnv/blob/master/direnvrc#L270