sennit

A dotfiles manager that keeps symlink semantics, and adds templating and drift detection.

sennit — braided cordage, made by plaiting many strands into a single line.

brew install ken109/tap/sennit   # or: cargo install sennit

Why another one?

Most dotfiles managers make you choose between two models, and both cost something:

• Symlink-based (GNU Stow, hand-rolled scripts) — ~/.config/nvim/init.lua is the file in your repository. Edit it in place and it shows up in git diff. But there is no templating, no way to preview what an apply will change, and nothing checks that the packages your configs depend on are actually installed.
• Copy-based (chezmoi) — you get templating and per-machine variants, but the source and the target are different files. Editing ~/.config directly is a mistake that gets silently reverted on the next apply.

sennit takes the position that this is a false choice. Templating and symlinking are only in tension for the files that actually need templating — usually a handful that carry a color palette. So sennit renders those into your repository, commits the result, and symlinks everything the same way. The live-edit loop survives for every other config.

Quick start

In the root of your dotfiles repository:

# sennit.toml — what to place
[link]
common = [".config", ".zshenv"]
darwin = [".hammerspoon"]
linux  = [".local"]
ignore = ["*.tmpl"]

sennit diff    # see what would change
sennit apply   # place the symlinks

sennit looks for sennit.toml by walking up from the current directory, so it works from anywhere inside your repository.

Directories are linked file by file rather than as a whole, so that a tool writing into ~/.config/something/ does not make untracked files appear inside your repository.

Commands

Every path is classified as one of four states, and only the ones that need work are touched:

Templating

Add a theme.toml (or any TOML file of values) and declare what is generated from what:

# sennit.toml
[render]
".config/alacritty/alacritty.toml" = ".config/alacritty/alacritty.toml.tmpl"

# theme.toml
[ui]
bg = "#1a1b26"
fg = "#c0caf5"

# .config/alacritty/alacritty.toml.tmpl
[colors.primary]
background = "{{ ui.bg }}"
foreground = "{{ ui.fg }}"

Templates do substitution and nothing else. There are deliberately no conditionals or loops: the moment a template gains control flow, it stops being readable as the config file it produces. An unknown variable is an error rather than an empty string, so a typo cannot quietly ship a broken config.

Generated files are meant to be committed. Run sennit render --check in CI to catch the case where a template was edited but the output was not regenerated.

Drift detection

The problem check solves is specific: you update a config, and forget to update the package list. The config references a tool that a fresh machine will never install, and nothing tells you until you set up that machine months later.

# packages.toml
[packages]
git-delta = { provides = ["delta"] }   # the command it installs is named differently
neovim    = { provides = ["nvim"] }

[packages.font-hack-nerd-font]
manager  = "brew-cask"
kind     = "font"
provides = ["Hack Nerd Font Mono"]

[packages.kubectl]
optional = true   # known dependency, deliberately not installed automatically

[ignore]
commands = ["brew", "git", "curl"]   # provided by the system or the bootstrap

check reads your configs with format-aware detectors rather than grepping for strings:

• commands invoked from git config (core.pager, interactive.diffFilter, credential helpers)
• font families in terminal and editor settings
• editor extensions declared for auto-install
• commands used in shell startup files
• the mere existence of .config/<tool>/, which is sometimes the only evidence of a dependency

Anything you deliberately do not install is declared optional = true, so the file records what is intentional rather than hiding it in an ignore list.

Installing packages

sync reads the same packages.toml and installs what is missing:

sennit sync --dry-run
sennit sync

It asks each manager what is already installed and only installs the difference, so idempotency does not depend on the manager's own behaviour.

Package names differ between distributions, so declare them where they do:

[packages.libyaml]
apt = "libyaml-dev"      # on Debian-like systems, use apt with this name
yay = "libyaml"          # on Arch-like systems, use yay with this name

On Linux, an apt or yay entry decides both the manager and the name. Without one, the default manager is used. Entries marked optional, or restricted to another OS via os = ["darwin"], are skipped. Editor extensions are declared so that check knows about them, but are installed by the editor itself.

sync does not replace your bootstrap script: something still has to install Homebrew, or sudo, before sennit can run at all.

Status

v0.3. Minimum supported Rust version is 1.90.

The author uses it to manage ken109/dotfiles; if you adopt it, start with sennit diff and --dry-run before the first apply, since apply will replace whatever is currently sitting at a managed path.

License

MIT