# Airflow Configuration

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## Configuration File

**Apache Airflow** generates a **config file** in all the airflow machines called **`airflow.cfg`** in the home of the airflow user. This config file contains configuration information and **might contain interesting and sensitive information.**

**There are two ways to access this file: By compromising some airflow machine, or accessing the web console.**

Note that the **values inside the config file** **might not be the ones used**, as you can overwrite them setting env variables such as `AIRFLOW__WEBSERVER__EXPOSE_CONFIG: 'true'`.

If you have access to the **config file in the web server**, you can check the **real running configuration** in the same page the config is displayed.\
If you have **access to some machine inside the airflow env**, check the **environment**.

Some interesting values to check when reading the config file:

### \[api]

- **`access_control_allow_headers`**: This indicates the **allowed** **headers** for **CORS**
- **`access_control_allow_methods`**: This indicates the **allowed methods** for **CORS**
- **`access_control_allow_origins`**: This indicates the **allowed origins** for **CORS**
- **`auth_backend`**: [**According to the docs**](https://airflow.apache.org/docs/apache-airflow/stable/security/api.html) a few options can be in place to configure who can access to the API:
  - `airflow.api.auth.backend.deny_all`: **By default nobody** can access the API
  - `airflow.api.auth.backend.default`: **Everyone can** access it without authentication
  - `airflow.api.auth.backend.kerberos_auth`: To configure **kerberos authentication**
  - `airflow.api.auth.backend.basic_auth`: For **basic authentication**
  - `airflow.composer.api.backend.composer_auth`: Uses composers authentication (GCP) (from [**here**](https://cloud.google.com/composer/docs/access-airflow-api)).
    - `composer_auth_user_registration_role`: This indicates the **role** the **composer user** will get inside **airflow** (**Op** by default).
  - You can also **create you own authentication** method with python.
- **`google_key_path`:** Path to the **GCP service account key**

### **\[atlas]**

- **`password`**: Atlas password
- **`username`**: Atlas username

### \[celery]

- **`flower_basic_auth`** : Credentials (_user1:password1,user2:password2_)
- **`result_backend`**: Postgres url which may contain **credentials**.
- **`ssl_cacert`**: Path to the cacert
- **`ssl_cert`**: Path to the cert
- **`ssl_key`**: Path to the key

### \[core]

- **`dag_discovery_safe_mode`**: Enabled by default. When discovering DAGs, ignore any files that don’t contain the strings `DAG` and `airflow`.
- **`fernet_key`**: Key to store encrypted variables (symmetric)
- **`hide_sensitive_var_conn_fields`**: Enabled by default, hide sensitive info of connections.
- **`security`**: What security module to use (for example kerberos)

### \[dask]

- **`tls_ca`**: Path to ca
- **`tls_cert`**: Part to the cert
- **`tls_key`**: Part to the tls key

### \[kerberos]

- **`ccache`**: Path to ccache file
- **`forwardable`**: Enabled by default

### \[logging]

- **`google_key_path`**: Path to GCP JSON creds.

### \[secrets]

- **`backend`**: Full class name of secrets backend to enable
- **`backend_kwargs`**: The backend_kwargs param is loaded into a dictionary and passed to **init** of secrets backend class.

### \[smtp]

- **`smtp_password`**: SMTP password
- **`smtp_user`**: SMTP user

### \[webserver]

- **`cookie_samesite`**: By default it's **Lax**, so it's already the weakest possible value
- **`cookie_secure`**: Set **secure flag** on the the session cookie
- **`expose_config`**: By default is False, if true, the **config** can be **read** from the web **console**
- **`expose_stacktrace`**: By default it's True, it will show **python tracebacks** (potentially useful for an attacker)
- **`secret_key`**: This is the **key used by flask to sign the cookies** (if you have this you can **impersonate any user in Airflow**)
- **`web_server_ssl_cert`**: **Path** to the **SSL** **cert**
- **`web_server_ssl_key`**: **Path** to the **SSL** **Key**
- **`x_frame_enabled`**: Default is **True**, so by default clickjacking isn't possible

### Web Authentication

By default **web authentication** is specified in the file **`webserver_config.py`** and is configured as

```bash
AUTH_TYPE = AUTH_DB
```

Which means that the **authentication is checked against the database**. However, other configurations are possible like

```bash
AUTH_TYPE = AUTH_OAUTH
```

To leave the **authentication to third party services**.

However, there is also an option to a**llow anonymous users access**, setting the following parameter to the **desired role**:

```bash
AUTH_ROLE_PUBLIC = 'Admin'
```

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