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DeerFlow uses a dual-configuration approach with YAML for core settings and JSON for extensions. The configuration system supports environment variable resolution, flexible file locations, and hot reloading.

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Configuration Files

DeerFlow uses two main configuration files:

config.yaml

Core application settings including models, tools, sandbox, and system behavior

extensions_config.json

Extensions configuration for MCP servers and skills enable/disable states

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File Locations

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Main Configuration (config.yaml)

DeerFlow resolves config.yaml in the following priority order:
1

Explicit Path Parameter

If you pass a config_path argument when loading configuration programmatically
2

DEER_FLOW_CONFIG_PATH Environment Variable

Set this variable to specify a custom config location:
export DEER_FLOW_CONFIG_PATH=/path/to/custom/config.yaml
3

Current Working Directory

Checks for config.yaml in the directory where DeerFlow is run
4

Parent Directory Fallback

If not found in CWD, checks the parent directory
If no config.yaml file is found, DeerFlow will raise a FileNotFoundError

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Extensions Configuration (extensions_config.json)

Extensions configuration follows a similar priority order:
1

DEER_FLOW_EXTENSIONS_CONFIG_PATH Environment Variable

export DEER_FLOW_EXTENSIONS_CONFIG_PATH=/path/to/extensions_config.json
2

Current Working Directory

Checks for extensions_config.json in CWD
3

Parent Directory

Falls back to parent directory if not found
4

Backward Compatibility

Also checks for legacy mcp_config.json filename
Extensions configuration is optional. If no file is found, DeerFlow continues with an empty extensions config

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Data Directory (DEER_FLOW_HOME)

DeerFlow stores persistent data (memory, threads, agent configurations) in a base directory resolved in this order:
1

DEER_FLOW_HOME Environment Variable

export DEER_FLOW_HOME=/custom/data/directory
2

Local Development Detection

If running from the backend/ directory, uses .deer-flow/ in that directory
3

Default User Home

Falls back to ~/.deer-flow/

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Directory Structure

The data directory (DEER_FLOW_HOME) has the following structure: 
{DEER_FLOW_HOME}/
├── memory.json              # Global memory storage
├── USER.md                  # Global user profile (injected into agents)
├── agents/                  # Custom agent configurations
│   └── {agent_name}/
│       ├── config.yaml      # Agent-specific config
│       ├── SOUL.md          # Agent personality/identity
│       └── memory.json      # Agent-specific memory
└── threads/                 # Per-thread working directories
    └── {thread_id}/
        └── user-data/       # Mounted as /mnt/user-data/ in sandbox
            ├── workspace/   # Agent's working directory
            ├── uploads/     # User-uploaded files
            └── outputs/     # Agent-generated artifacts

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Environment Variable Resolution

Both configuration files support environment variable resolution using the $VAR_NAME syntax:
config.yaml
models:
  - name: gpt-4
    use: langchain_openai:ChatOpenAI
    model: gpt-4
    api_key: $OPENAI_API_KEY  # Resolved from environment
    max_tokens: 4096
extensions_config.json
{
  "mcpServers": {
    "github": {
      "enabled": true,
      "type": "stdio",
      "command": "npx",
      "env": {
        "GITHUB_TOKEN": "$GITHUB_TOKEN"  // Resolved from environment
      }
    }
  }
}
If a referenced environment variable is not set, DeerFlow will raise a ValueError during configuration loading

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Configuration Loading

Configuration is loaded once at startup and cached as a singleton: 
from src.config.app_config import get_app_config

# Get cached config (loads on first call)
config = get_app_config()

# Access configuration
model = config.get_model_config("gpt-4")
tool = config.get_tool_config("web_search")

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Hot Reloading

You can reload configuration without restarting the application: 
from src.config.app_config import reload_app_config
from src.config.extensions_config import reload_extensions_config

# Reload main config
config = reload_app_config()

# Reload extensions config
extensions = reload_extensions_config()
Hot reloading is useful during development or when updating API keys without downtime

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Configuration Validation

DeerFlow uses Pydantic for configuration validation. Invalid configurations will raise detailed validation errors at startup: 
pydantic_core._pydantic_core.ValidationError: 2 validation errors for AppConfig
models.0.name
  Field required [type=missing, input_value={'use': 'langchain_openai..., 'max_tokens': 4096}, input_type=dict]
models.0.model
  Field required [type=missing, input_value={'use': 'langchain_openai..., 'max_tokens': 4096}, input_type=dict]

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Getting Started

1

Copy Example Configuration

cp config.example.yaml config.yaml
cp extensions_config.example.json extensions_config.json
2

Set Environment Variables

Create a .env file or export variables:
export OPENAI_API_KEY="sk-..."
export ANTHROPIC_API_KEY="sk-ant-..."
export GITHUB_TOKEN="ghp_..."
3

Customize Configuration

Edit config.yaml to configure models, tools, and sandbox settings
4

Enable Extensions

Edit extensions_config.json to enable/disable MCP servers and skills

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Next Steps

Models Configuration

Configure LLM models and providers

Sandbox Modes

Set up local, Docker, or Kubernetes sandboxes

Skills & MCP

Configure skills and MCP servers

Memory Configuration

Set up the memory system