Configuration Overview DocuGen AI supports multiple configuration methods with a clear precedence order. This allows you to set defaults globally while overriding them per-project or per-command.
Configuration Precedence Configuration values are resolved in the following order (highest to lowest priority):
CLI arguments - Direct command-line optionsTOML configuration files - Project or user config filesDefault values - Built-in defaults
Configuration Methods CLI Arguments
TOML Files
Environment Variables
.env Files
Command-Line Options The most direct way to configure DocuGen is via CLI arguments. These always take precedence over other configuration methods. docugen generate . \ --output DOCS.md \ --model gemini-pro \ --prompt "Focus on API documentation"
Available CLI options:
--output, -o - Output file path--model - Gemini model name--prompt, -p - Additional AI instructions--config - Path to TOML config file See CLI Reference for complete details. TOML Configuration Files TOML files provide a convenient way to set default configurations for projects or your user account. Configuration File Locations DocuGen searches for TOML configuration files in this order:
Explicit path (via --config option or DOCUGEN_CONFIG env var)Current directory: ./.docugen.tomlUser config directory: ~/.config/docugen/config.tomlUser home directory: ~/.docugen.toml The first file found is used. Values from the file are merged and used as defaults. Option 1: Flat structure model = "gemini-pro" output = "DOCUMENTATION.md"
Option 2: Nested under [docugen] section [ docugen ] model = "gemini-pro" output = "DOCUMENTATION.md"
Option 3: Mixed (nested values override flat values) model = "gemini-3.1-flash-lite-preview" [ docugen ] model = "gemini-pro" # This takes precedence output = "README.md"
Available TOML Keys Key Type Description Default modelstring Gemini model name "gemini-3.1-flash-lite-preview"outputstring Output file path "README.md"
The --prompt option is typically unique per-generation and is not commonly set in TOML files.
Environment Variables DocuGen uses environment variables for sensitive configuration like API keys and for specifying configuration file paths. API Key Configuration Your Google Gemini API key. This is required for DocuGen to function. Setting the variable: # Linux/macOS export GEMINI_API_KEY = "your-api-key-here" # Windows (Command Prompt) set GEMINI_API_KEY=your-api-key-here # Windows (PowerShell) $env : GEMINI_API_KEY = "your-api-key-here"
Never commit your API key to version control. Use environment variables or .env files (which should be in .gitignore).
Configuration Path Variables Specifies a custom TOML configuration file path. This takes precedence over the default search locations. export DOCUGEN_CONFIG = "/path/to/custom/config.toml" docugen generate .
Specifies a custom .env file path for loading environment variables. export DOCUGEN_DOTENV = "/path/to/custom/.env" docugen generate .
.env Files For convenience, DocuGen can load environment variables from .env files. This is particularly useful for the GEMINI_API_KEY. .env File Locations DocuGen searches for .env files in this order:
Explicit path (via DOCUGEN_DOTENV environment variable)Current working directory: ./.envDocuGen installation directory: <docugen-root>/.env The first file found is parsed for environment variables. # Google Gemini API Key (required) GEMINI_API_KEY = your-api-key-here # Optional: specify custom config location DOCUGEN_CONFIG = /path/to/config.toml
Supported formats:
Standard format: KEY=value
With quotes: KEY="value" or KEY='value'
With export: export KEY=value
Comments: Lines starting with # are ignored
Creating a .env File Project Directory
Template
# Create .env in your project cd /path/to/your/project echo 'GEMINI_API_KEY=your-api-key-here' > .env # Add to .gitignore echo '.env' >> .gitignore
Always add .env to your .gitignore file to prevent accidentally committing sensitive API keys.
Configuration Parameters API Key Source: GEMINI_API_KEY environment variable or .env fileYour Google Gemini API key. Obtain one from Google AI Studio . Resolution order:
GEMINI_API_KEY environment variableGEMINI_API_KEY in .env file (current directory)GEMINI_API_KEY in .env file (DocuGen installation directory) Model model
string
default: "gemini-3.1-flash-lite-preview"
Sources: CLI --model, TOML model keyThe Gemini model to use for generating documentation. Popular options:
gemini-3.1-flash-lite-preview - Fastest, recommended for most projectsgemini-pro - Balanced performance and qualitygemini-ultra - Highest quality, slower Resolution order:
--model CLI argumentmodel in TOML config fileDefault: "gemini-3.1-flash-lite-preview"
Output Path output
string
default: "README.md"
Sources: CLI --output, TOML output keyPath where the generated documentation will be written.
Relative paths are resolved from the project directory
Absolute paths are used as-is
Parent directories are created automatically
Resolution order:
--output (or -o) CLI argumentoutput in TOML config fileDefault: "README.md"
Custom Prompt Source: CLI --prompt onlyAdditional instructions for the AI to customize the generated documentation. This parameter is only available via CLI (not TOML) as it’s typically unique per-generation.
Complete Configuration Examples Example 1: Personal Development Setup ~/.config/docugen/config.toml: [ docugen ] model = "gemini-pro" output = "README.md"
~/.zshrc or ~/.bashrc: export GEMINI_API_KEY = "your-api-key-here"
Usage: # Uses your personal config and API key docugen generate .
Example 2: Project-Specific Configuration Project structure: my_project/ ├── .env ├── .docugen.toml ├── .gitignore └── src/
.env: GEMINI_API_KEY = project-specific-key
.docugen.toml: model = "gemini-ultra" output = "docs/API_REFERENCE.md"
.gitignore: Usage: cd my_project docugen generate ./src # Generates: my_project/docs/API_REFERENCE.md # Uses: gemini-ultra model and project-specific API key
Example 3: Team Shared Configuration Committed to repository: .docugen.toml: # Team defaults model = "gemini-pro" output = "docs/README.md"
.env.example: # Copy to .env and add your key GEMINI_API_KEY = your-key-here
.gitignore: Each developer creates their own .env: cp .env.example .env # Edit .env with your personal API key
Example 4: Override Everything via CLI # CLI arguments override all configuration files docugen generate ./src \ --config /custom/config.toml \ --model gemini-pro \ --output /tmp/docs.md \ --prompt "Focus on async patterns"
Troubleshooting
Missing GEMINI_API_KEY error
Error: Missing GEMINI_API_KEY (set it in environment or .env).Solutions:
Set the environment variable:
export GEMINI_API_KEY = "your-key"
Create a .env file in your project directory:
echo 'GEMINI_API_KEY=your-key' > .env
Verify the variable is set:
Configuration file not found
Issue: DocuGen isn’t using your TOML configuration.Check:
Verify the file exists in one of the search locations:
ls -la .docugen.toml ls -la ~/.config/docugen/config.toml ls -la ~/.docugen.toml
Check for TOML syntax errors:
# Invalid TOML will be silently ignored # Verify syntax at: https://www.toml-lint.com/
Specify explicitly:
docugen generate . --config ./path/to/config.toml
.env file not being loaded
Issue: Environment variables from .env aren’t being used.Solutions:
Verify file location:
Check file format (no spaces around =):
cat .env # Correct: GEMINI_API_KEY=value # Wrong: GEMINI_API_KEY = value
Specify explicitly:
export DOCUGEN_DOTENV = "./path/to/.env"
Best Practices
Use .env for Secrets Store API keys in .env files and add them to .gitignore. Never commit secrets to version control.
Use TOML for Defaults Set project or user defaults in TOML files. Commit project configs (without secrets) to share with team.
Use CLI for Overrides Override defaults with CLI arguments for one-off customizations or testing.
Document for Teams Include .env.example and .docugen.toml in your repository to help team members get started quickly.
