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The dlt.config accessor provides dictionary-like access to configuration values. Use it to access non-sensitive configuration values like API endpoints, batch sizes, or feature flags.

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Basic Usage

import dlt

# Access config values
api_url = dlt.config["api_url"]
batch_size = dlt.config.get("batch_size", int)

# Check if config exists
if "custom_setting" in dlt.config:
    value = dlt.config["custom_setting"]

# Set config values programmatically
dlt.config["runtime.setting"] = "value"

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Methods

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__getitem__(field: str)

Get a configuration value by field name. Raises ConfigFieldMissingException if not found.
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field
str
required
Configuration key to retrieve. Use dot notation for nested values (e.g., "sources.github.api_url").
Returns: The configuration value, automatically cast to appropriate type. Example: 
api_url = dlt.config["sources.github.api_url"]

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get(field: str, expected_type: Type = None)

Get a configuration value with optional type casting. Returns None if not found.
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field
str
required
Configuration key to retrieve.
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expected_type
Type
default:"None"
Expected type to deserialize the value into (e.g., int, bool, list).
Returns: The configuration value cast to expected_type, or None if not found. Example: 
max_retries = dlt.config.get("api.max_retries", int)
timeout = dlt.config.get("api.timeout", float)

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__setitem__(field: str, value: Any)

Set a configuration value programmatically.
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field
str
required
Configuration key to set. Use dot notation for sections.
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value
Any
required
Value to store.
Example: 
dlt.config["sources.custom.endpoint"] = "https://api.example.com"

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__contains__(field: str)

Check if a configuration value exists. Example: 
if "optional_setting" in dlt.config:
    process(dlt.config["optional_setting"])

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Automatic Injection with dlt.config.value

Use dlt.config.value as a default argument value to automatically inject configuration: 
import dlt
from dlt.sources.helpers import requests

@dlt.resource
def my_resource(api_url=dlt.config.value, batch_size=dlt.config.value):
    """dlt will automatically inject api_url and batch_size from config"""
    response = requests.get(api_url)
    yield response.json()
Configuration lookup paths:
  • sources.<source_name>.<resource_name>.<arg_name>
  • sources.<source_name>.<arg_name>
  • <arg_name>

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Configuration Sources

The dlt.config accessor reads from multiple providers in order:
  1. Environment variables (e.g., SOURCES__GITHUB__API_URL)
  2. config.toml file in .dlt/ directory
  3. secrets.toml file (config can also be stored here)
  4. Airflow Variables (when running in Airflow)
  5. Google Secret Manager, AWS Secrets Manager, etc. (if configured)
Note: For sensitive values like passwords and API tokens, use dlt.secrets instead.

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Configuration File Example

In .dlt/config.toml: 
[sources.github]
api_url = "https://api.github.com"
max_items_per_page = 100

[runtime]
batch_size = 1000
timeout = 30.0

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Environment Variables

Configuration can be provided via environment variables using double underscores for nesting: 
export SOURCES__GITHUB__API_URL="https://api.github.com"
export RUNTIME__BATCH_SIZE="1000"

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See Also

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