Configuration

Config file

yaku stores configuration in a YAML file. Find its location with:

~/.config/yaku/config.yaml

yaku config path

The file is created automatically when you first run yaku config set. You can also edit it directly — yaku preserves comments and formatting.

All config fields

Field	Type	Default	Description
api-key	string		LLM API key for local backends (Gemini, OpenAI, Anthropic).
default-target	string		Default target language. Lets you omit --to.
backend	string	hosted	LLM backend: hosted, gemini, openai, anthropic. Validated on set.
model	string	backend default	Model name override (e.g., gemini-2.5-flash, gpt-4o-mini).
api-base	string		API base URL override for any local backend. Commonly used with OpenAI-compatible providers.
hosted-url	string	https://api.yakulang.com	Hosted service API endpoint. Auth endpoints are derived automatically (strips api. prefix).
prompt	string		Path to a custom system prompt file. Applied to every translation.

Note

Authentication credentials are stored separately in ~/.config/yaku/.credentials, not in the config file. This file is managed automatically by yaku login and yaku logout — you should not edit it manually.

Example config file

~/.config/yaku/config.yaml

api-key: AIzaSy...your-gemini-key
default-target: en
backend: gemini
model: gemini-2.5-flash

Managing config

# Set a value
yaku config set default-target zh-TW

# Read a value (from file only, ignores environment variables)
yaku config get default-target

# Find the config file
yaku config path

Environment variables

Environment variables override config file values. This is useful for CI/CD, containers, or switching between projects.

Variable	Overrides config field	Example
YAKU_API_KEY	api-key	export YAKU_API_KEY=AIza...
YAKU_DEFAULT_TARGET	default-target	export YAKU_DEFAULT_TARGET=zh-TW
YAKU_BACKEND	backend	export YAKU_BACKEND=openai
YAKU_MODEL	model	export YAKU_MODEL=gpt-4o
YAKU_API_BASE	api-base	export YAKU_API_BASE=https://api.groq.com/openai/v1
YAKU_HOSTED_URL	hosted-url	export YAKU_HOSTED_URL=https://api.staging.yakulang.com

Environment variable override behavior

When a YAKU_* environment variable is set — even to an empty string — it overrides the corresponding config file value. This prevents silent fallback when a key source fails:

# Explicitly empty → overrides config file, key becomes empty
YAKU_API_KEY="" yaku --backend gemini --to en "test"
# Error: YAKU_API_KEY is set but empty (check your key source).

Backend-specific API key fallbacks

When YAKU_API_KEY is not set at all (not even to an empty string) and there is no api-key in the config file, yaku checks these backend-specific environment variables based on the resolved backend (including the --backend flag):

Backend	Fallback variable
gemini	GOOGLE_API_KEY
openai	OPENAI_API_KEY
anthropic	ANTHROPIC_API_KEY

This means you can use existing environment variables from other tools (e.g., the Google Cloud SDK or OpenAI CLI) without additional configuration. Combined with --backend, you can switch between providers without changing your config:

export GOOGLE_API_KEY=your-gemini-key
export OPENAI_API_KEY=your-openai-key
yaku --backend gemini --to en "Bonjour"
yaku --backend openai --to en "Bonjour"

Precedence order

When the same setting is specified in multiple places, the highest-priority source wins:

1. Command-line flag (highest) — e.g., --to ja
2. Environment variable — e.g., YAKU_DEFAULT_TARGET=ja
3. Config file — ~/.config/yaku/config.yaml
4. Built-in default (lowest)

Example: If your config file has default-target: en but you run yaku --to ja, the target language is ja.

Error handling

• Missing config file: yaku uses built-in defaults. No error.
• YAML syntax error: yaku logs a warning to stderr and continues with defaults.
• Unknown config key: yaku config set rejects keys that are not in the list above.
• Invalid config value: yaku config set validates values. Backend must be one of hosted, gemini, openai, anthropic. The default-target field must be a valid BCP 47 language code.