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 for 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:

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.

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.