Chezmoi Expert

Chezmoi Expert

Overview

This skill provides expert-level knowledge for using chezmoi, a dotfile manager that maintains consistent configurations across multiple machines. It covers advanced template systems, secure secrets management, script automation, external file management, multi-machine strategies, performance optimization, and comprehensive troubleshooting techniques.

When to Use This Skill

Use this skill when:

• Working with chezmoi dotfile configurations
• Setting up new machines with dotfiles
• Implementing machine-specific configurations
• Managing secrets securely in dotfiles
• Creating template-based configurations
• Automating setup with scripts
• Managing external dependencies
• Optimizing chezmoi performance
• Debugging chezmoi issues
• Migrating to or between chezmoi setups

Core Principles

Declarative State Management

Chezmoi operates on a declarative model with three key states:

• Source State: Desired configuration stored in ~/.local/share/chezmoi
• Target State: Computed desired state based on source + config + templates
• Destination State: Current state of files in home directory

Template-Driven Configuration

Use Go templates with Sprig functions to create machine-specific configurations from a single source. Templates evaluate based on:

• Built-in variables (.chezmoi.os, .chezmoi.hostname, etc.)
• Config file data (~/.config/chezmoi/chezmoi.toml)
• Static data files (.chezmoidata/)
• External sources (password managers, commands)

Idempotent Operations

All operations should be safe to run multiple times. Scripts should check state before making changes. Templates should produce consistent output for the same inputs.

Quick Reference

Common Operations

Edit and apply:

chezmoi edit --apply ~/.zshrc

Preview changes:

chezmoi diff

Apply changes:

chezmoi apply --verbose

Add new file:

chezmoi add --template ~/.gitconfig

Update from remote:

chezmoi update

Check system health:

chezmoi doctor

Test template:

chezmoi execute-template "{{ .chezmoi.hostname }}"

File Naming Conventions

Understanding chezmoi file naming is essential:

• dot_filename → .filename
• private_dot_filename → .filename (mode 600)
• executable_filename → filename (mode +x)
• exact_dirname → dirname/ (removes unmanaged files)
• encrypted_filename.age → filename (decrypted with age)
• filename.tmpl → filename (template evaluated)
• symlink_name → symlink to target

Prefixes can be combined: private_encrypted_dot_ssh/private_encrypted_id_rsa.age.tmpl

Working with Templates

Data Sources Priority

Chezmoi loads data in this order (later sources override earlier):

1. Built-in variables (.chezmoi.*)
2. Static data files (.chezmoidata.$FORMAT)
3. Data directories (.chezmoidata/*.yaml)
4. Config file data (chezmoi.toml [data] section)

Creating Templates

Convert existing file to template:

chezmoi add --template ~/.gitconfig

Test template rendering:

chezmoi cat ~/.gitconfig
chezmoi execute-template "{{ .user.email }}"

Common Template Patterns

OS-specific logic:

{{ if eq .chezmoi.os "darwin" -}}
macOS configuration
{{ else if eq .chezmoi.os "linux" -}}
Linux configuration
{{ end -}}

Machine-class logic:

{{ if eq .machine_class "work" -}}
work-specific configuration
{{ else -}}
personal configuration
{{ end -}}

Include files with change detection:

# Hash triggers script rerun when file changes
# config.ini hash: {{ include "config.ini" | sha256sum }}

For detailed template system documentation, reference references/templates.md.

Managing Secrets

Never commit plaintext secrets to the repository. Use these approaches:

Password Manager Integration

Chezmoi provides built-in functions for major password managers:

1Password:

{{ onepasswordRead "op://vault/item/field" }}

Bitwarden:

{{ (bitwarden "item" "name").login.password }}

Pass:

{{ pass "path/to/secret" }}

Encryption

For secrets that must be stored in repository:

Age encryption (recommended):

# Generate key
chezmoi age decrypt --generate > ~/.config/chezmoi/key.txt

# Add encrypted file
chezmoi add --encrypt ~/.ssh/id_rsa

GPG encryption:

# Configure recipient in chezmoi.toml
chezmoi add --encrypt ~/.netrc

Best Practice: Centralize Secret Retrieval

Call password managers once in config template (.chezmoi.toml.tmpl), not in every file template:

# .chezmoi.toml.tmpl
[data.secrets]
  github_token = {{ onepasswordRead "op://vault/github/token" | quote }}
  
# Then reference in templates:
# {{ .secrets.github_token }}

For comprehensive secrets documentation, reference references/secrets.md.

Script Automation

Scripts execute during chezmoi apply to automate setup tasks.

Script Types

• run_before_*: Runs before applying files (prerequisites)
• run_after_*: Runs after applying files (post-configuration)
• run_onchange_*: Runs when script content changes (recommended)
• run_once_*: Runs once per machine (tracked in state)
• run_always_*: Runs every time (use sparingly)

Script Execution Order

Scripts execute alphabetically. Use numeric prefixes for control:

run_once_before_01-install-brew.sh
run_once_before_02-install-packages.sh
run_onchange_after_99-cleanup.sh

Template Scripts

Add .tmpl suffix for platform-specific scripts:

# run_onchange_install-packages.sh.tmpl
{{ if eq .chezmoi.os "darwin" -}}
#!/bin/bash
brew install package
{{ else if eq .chezmoi.os "linux" -}}
#!/bin/bash
sudo apt install -y package
{{ end -}}

Trigger on File Changes

Embed file hashes to rerun scripts when dependencies change:

# Brewfile hash: {{ include "Brewfile" | sha256sum }}
brew bundle --file={{ joinPath .chezmoi.sourceDir "Brewfile" | quote }}

Best Practices

• Use set -euo pipefail in bash scripts
• Make scripts idempotent (safe to run multiple times)
• Check prerequisites before using commands
• Prefer run_onchange_ over run_always_
• Use run_once_ for expensive one-time operations

For detailed script documentation, reference references/scripts.md.

External File Management

Manage files from external sources without storing them in repository.

External Types

.chezmoiexternal.toml.tmpl:

Single file:

[".vim/autoload/plug.vim"]
  type = "file"
  url = "https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim"
  refreshPeriod = "168h"

Archive:

[".oh-my-zsh"]
  type = "archive"
  url = "https://github.com/ohmyzsh/ohmyzsh/archive/master.tar.gz"
  exact = true
  stripComponents = 1
  refreshPeriod = "168h"

Git repository:

[".config/nvim"]
  type = "git-repo"
  url = "https://github.com/NvChad/NvChad.git"
  refreshPeriod = "168h"

Platform-specific binary:

[".local/bin/age"]
  type = "archive-file"
  url = "https://github.com/FiloSottile/age/releases/download/v1.1.1/age-v1.1.1-{{ .chezmoi.os }}-{{ .chezmoi.arch }}.tar.gz"
  executable = true
  path = "age/age"
  refreshPeriod = "168h"

Refresh Management

Set refreshPeriod to avoid checking on every apply:

• Weekly: 168h
• Daily: 24h
• Manual only: 0

Force refresh when needed:

chezmoi apply --refresh-externals

For comprehensive externals documentation, reference references/externals.md.

Multi-Machine Configuration

Recommended Strategy: Config File Data + OS Detection

Each machine (~/.config/chezmoi/chezmoi.toml):

[data]
  machine_class = "work"  # or "personal", "server"
  email = "john@company.com"

[data.features]
  work_tools = true
  gaming = false

Templates use both machine config and OS detection:

# dot_gitconfig.tmpl
[user]
  email = {{ .email | quote }}

{{ if eq .chezmoi.os "darwin" -}}
[credential]
  helper = osxkeychain
{{ end -}}

{{ if eq .machine_class "work" -}}
[http]
  proxy = http://proxy.company.com
{{ end -}}

Control file installation with .chezmoiignore:

{{ if ne .machine_class "work" }}
.work-config/**
{{ end }}

{{ if ne .chezmoi.os "darwin" }}
.config/aerospace/**
{{ end }}

Machine-Specific Externals

Template .chezmoiexternal.toml.tmpl to download different tools per machine:

{{ if .features.work_tools -}}
[".local/bin/work-cli"]
  type = "file"
  url = "https://internal.company.com/cli"
{{ end -}}

For multi-machine strategies and patterns, reference references/multi-machine.md.

Common Workflows

Daily Workflow

# Edit file
chezmoi edit --watch ~/.zshrc

# Preview changes
chezmoi diff

# Apply changes
chezmoi apply

# Commit and push
chezmoi cd
git add .
git commit -m "Update config"
git push

Multi-Machine Sync

Machine A (make changes):

chezmoi edit ~/.gitconfig
chezmoi apply
chezmoi cd && git add . && git commit -m "Update" && git push

Machine B (get changes):

chezmoi update  # Pull and apply

New Machine Setup

sh -c "$(curl -fsLS get.chezmoi.io)" -- init --apply username

For detailed workflows and patterns, reference references/workflows.md.

Performance Optimization

Key Optimizations

1. Set refreshPeriod on externals: Prevent checking on every apply
2. Minimize password manager calls: Call once in config template
3. Use run_onchange over run_always: Reduce script execution
4. Simplify templates: Extract complex logic to config
5. Use .chezmoiignore: Skip irrelevant files

Measure Performance

time chezmoi apply
chezmoi apply --verbose 2>&1 | grep -E "took|duration"

For comprehensive performance optimization, reference references/performance.md.

Troubleshooting

Diagnostic Commands

# Quick health check
chezmoi doctor

# Show available data
chezmoi data

# Test template
chezmoi execute-template "{{ .variable }}"

# Preview file rendering
chezmoi cat ~/.gitconfig

# Debug mode
chezmoi apply --debug --dry-run

Common Issues

Template variable not found:

chezmoi data | grep variable  # Check if defined
chezmoi edit-config           # Add to config

Script not running:

# Check naming (run_onchange_ prefix)
ls ~/.local/share/chezmoi/ | grep run_

# Clear state to force rerun
chezmoi state delete-bucket --bucket=scriptState

Permission denied:

# Make file executable or private
chezmoi chattr +executable ~/.local/bin/script
chezmoi chattr +private ~/.ssh/config

Encryption fails:

# Verify encryption key
ls ~/.config/chezmoi/key.txt
chezmoi cat-config | grep age

For comprehensive troubleshooting, reference references/troubleshooting.md.

Advanced Patterns

Template Fragments

Reuse common template logic:

# .chezmoitemplates/git-config
[user]
  name = "{{ .user.name }}"
  email = "{{ .user.email }}"

# In dot_gitconfig.tmpl:
{{ template "git-config" . }}

Derived Data

Compute values once in config template:

# .chezmoi.toml.tmpl
[data]
{{- if and (eq .chezmoi.os "darwin") (eq .chezmoi.arch "arm64") }}
  platform = "macos-arm"
{{- else if eq .chezmoi.os "linux" }}
  platform = "linux"
{{- end }}

# Use in templates:
# {{ if eq .platform "macos-arm" }}...{{ end }}

Feature Flags

Control optional functionality:

# chezmoi.toml
[data.features]
  experimental = true
  beta_ui = false
  work_tools = true

# In templates:
{{ if .features.experimental -}}
# experimental configuration
{{ end -}}

Reference Documentation

This skill includes comprehensive reference documentation:

• templates.md: Complete template system guide with data sources, syntax, functions, and patterns
• secrets.md: Password manager integration, encryption (age/GPG), and best practices
• scripts.md: Script execution types, environment, error handling, and common patterns
• externals.md: External file management, types, refresh strategies, and troubleshooting
• workflows.md: Daily operations, multi-machine sync, file management patterns
• troubleshooting.md: Diagnostic commands, common issues, debugging techniques
• performance.md: Optimization strategies for externals, templates, scripts, and git
• multi-machine.md: Configuration strategies for managing multiple machines

Reference these documents for detailed information on specific topics.

Best Practices Summary

1. Version control everything: Commit source directory to git
2. Never commit secrets: Use password managers or encryption
3. Use templates wisely: Only template files that need variation
4. Make scripts idempotent: Safe to run multiple times
5. Set refreshPeriod: On all external files
6. Test before applying: Use --dry-run --verbose
7. Document machine setup: README with initialization instructions
8. Keep it simple: Start basic, add complexity as needed
9. Use feature flags: Better than machine-specific conditionals
10. Monitor performance: Profile and optimize slow operations

Getting Started

For new users or new machines:

1. Install chezmoi and initialize from repository
2. Configure machine-specific data in ~/.config/chezmoi/chezmoi.toml
3. Preview changes with chezmoi diff
4. Apply dotfiles with chezmoi apply
5. Verify with chezmoi doctor

For advanced users:

• Reference detailed documentation in references/ for specific topics
• Use chezmoi execute-template to test template logic
• Profile performance with time chezmoi apply --verbose
• Leverage all script types for comprehensive automation
• Implement multi-machine strategies for different environments