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# Secrets and Environment Variables
## Creating Secrets
### Via Dashboard
Create secrets at https://modal.com/secrets
Templates available for:
- Database credentials (Postgres, MongoDB)
- Cloud providers (AWS, GCP, Azure)
- ML platforms (Weights & Biases, Hugging Face)
- And more
### Via CLI
```bash
# Create secret with key-value pairs
modal secret create my-secret KEY1=value1 KEY2=value2
# Use environment variables
modal secret create db-secret PGHOST=uri PGPASSWORD="$PGPASSWORD"
# List secrets
modal secret list
# Delete secret
modal secret delete my-secret
```
### Programmatically
From dictionary:
```python
if modal.is_local():
local_secret = modal.Secret.from_dict({"FOO": os.environ["LOCAL_FOO"]})
else:
local_secret = modal.Secret.from_dict({})
@app.function(secrets=[local_secret])
def some_function():
import os
print(os.environ["FOO"])
```
From .env file:
```python
@app.function(secrets=[modal.Secret.from_dotenv()])
def some_function():
import os
print(os.environ["USERNAME"])
```
## Using Secrets
Inject secrets into functions:
```python
@app.function(secrets=[modal.Secret.from_name("my-secret")])
def some_function():
import os
secret_key = os.environ["MY_PASSWORD"]
# Use secret
...
```
### Multiple Secrets
```python
@app.function(secrets=[
modal.Secret.from_name("database-creds"),
modal.Secret.from_name("api-keys"),
])
def other_function():
# All keys from both secrets available
...
```
Later secrets override earlier ones if keys clash.
## Environment Variables
### Reserved Runtime Variables
**All Containers**:
- `MODAL_CLOUD_PROVIDER` - Cloud provider (AWS/GCP/OCI)
- `MODAL_IMAGE_ID` - Image ID
- `MODAL_REGION` - Region identifier (e.g., us-east-1)
- `MODAL_TASK_ID` - Container task ID
**Function Containers**:
- `MODAL_ENVIRONMENT` - Modal Environment name
- `MODAL_IS_REMOTE` - Set to '1' in remote containers
- `MODAL_IDENTITY_TOKEN` - OIDC token for function identity
**Sandbox Containers**:
- `MODAL_SANDBOX_ID` - Sandbox ID
### Setting Environment Variables
Via Image:
```python
image = modal.Image.debian_slim().env({"PORT": "6443"})
@app.function(image=image)
def my_function():
import os
port = os.environ["PORT"]
```
Via Secrets:
```python
secret = modal.Secret.from_dict({"API_KEY": "secret-value"})
@app.function(secrets=[secret])
def my_function():
import os
api_key = os.environ["API_KEY"]
```
## Common Secret Patterns
### AWS Credentials
```python
aws_secret = modal.Secret.from_name("my-aws-secret")
@app.function(secrets=[aws_secret])
def use_aws():
import boto3
s3 = boto3.client('s3')
# AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY automatically used
```
### Hugging Face Token
```python
hf_secret = modal.Secret.from_name("huggingface")
@app.function(secrets=[hf_secret])
def download_model():
from transformers import AutoModel
# HF_TOKEN automatically used for authentication
model = AutoModel.from_pretrained("private-model")
```
### Database Credentials
```python
db_secret = modal.Secret.from_name("postgres-creds")
@app.function(secrets=[db_secret])
def query_db():
import psycopg2
conn = psycopg2.connect(
host=os.environ["PGHOST"],
port=os.environ["PGPORT"],
user=os.environ["PGUSER"],
password=os.environ["PGPASSWORD"],
)
```
## Best Practices
1. **Never hardcode secrets** - Always use Modal Secrets
2. **Use specific secrets** - Create separate secrets for different purposes
3. **Rotate secrets regularly** - Update secrets periodically
4. **Minimal scope** - Only attach secrets to functions that need them
5. **Environment-specific** - Use different secrets for dev/staging/prod
## Security Notes
- Secrets are encrypted at rest
- Only available to functions that explicitly request them
- Not logged or exposed in dashboards
- Can be scoped to specific environments