For AWS Aurora PostgreSQL with IAM authentication, you'll need to configure Prefect to use a connection string that supports IAM token-based authentication. Here's how to do it: 1. First, ensure you have the required dependencies installed:

bash
pip install "prefect[database]" boto3

2. You'll need to set up your connection string using the following format in your environment variables:

bash
export PREFECT_API_DATABASE_CONNECTION_URL="postgresql+psycopg2://<USER>@<AURORA-ENDPOINT>:5432/<DATABASE>?aws_auth=true"

3. Ensure your AWS credentials are properly configured. You can do this through: - Environment variables (

AWS_ACCESS_KEY_ID

,

AWS_SECRET_ACCESS_KEY

,

AWS_REGION

) - AWS credentials file (

~/.aws/credentials

) - IAM role if running on AWS infrastructure 4. If you're running Prefect server in a container, make sure to pass through both the database connection URL and AWS credentials:

bash
docker run -e PREFECT_API_DATABASE_CONNECTION_URL=... \
           -e AWS_ACCESS_KEY_ID=... \
           -e AWS_SECRET_ACCESS_KEY=... \
           -e AWS_REGION=... \
           prefecthq/prefect:2-latest

A few important notes: - The

aws_auth=true

parameter in the connection string tells SQLAlchemy to use IAM authentication - Make sure the IAM user/role has the

rds-db:connect

permission for your Aurora cluster - The database user in the connection string must match an IAM user/role that has been granted access to the database - If you're using a custom AWS endpoint (like for LocalStack or a specific region), you can add

rds_region_name=<region>

to your connection string parameters This configuration allows Prefect to automatically handle token generation and renewal when connecting to your Aurora PostgreSQL database. If you run into any specific errors during setup, please share them and I can provide more targeted assistance.

To fix this error, you need to: 1. First, install the required async PostgreSQL driver:

bash
pip install "prefect[database]" asyncpg boto3

2. Modify your connection string to use the

postgresql+asyncpg

dialect instead of `postgresql+psycopg2`:

bash
export PREFECT_API_DATABASE_CONNECTION_URL="postgresql+asyncpg://<USER>@<AURORA-ENDPOINT>:5432/<DATABASE>?aws_auth=true"

The error you're seeing occurs because Prefect 3.x uses async database connections, and

psycopg2

is a synchronous driver. The

asyncpg

driver is the async-compatible alternative that works with Prefect 3.x's async architecture. If you're running this in a container, remember to update your docker run command accordingly with the new connection string:

bash
docker run -e PREFECT_API_DATABASE_CONNECTION_URL="postgresql+asyncpg://..." \
           -e AWS_ACCESS_KEY_ID=... \
           -e AWS_SECRET_ACCESS_KEY=... \
           -e AWS_REGION=... \
           prefecthq/prefect:latest

Let me know if you encounter any other issues after making this change.

For

asyncpg

with Aurora IAM authentication, you'll need to generate the authentication token manually and provide it in the connection string. Here's how to do it: 1. First, install the required AWS authentication package:

bash
pip install boto3

2. Create a helper script to generate the auth token. Save this as `get_aurora_token.py`:

python
import boto3

def get_aurora_token(
    aurora_host: str,
    port: int,
    region: str,
    username: str,
) -> str:
    client = boto3.client('rds', region_name=region)
    token = client.generate_db_auth_token(
        DBHostname=aurora_host,
        Port=port,
        DBUsername=username,
        Region=region
    )
    return token

3. Now, you can set up your Prefect database URL using the generated token. Set this in your environment:

python
import os
from get_aurora_token import get_aurora_token

aurora_host = "your-aurora-cluster-endpoint"
port = 5432
region = "your-aws-region"
username = "your-iam-user"
database = "your-database-name"

token = get_aurora_token(
    aurora_host=aurora_host,
    port=port,
    region=region,
    username=username
)

os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = (
    f"postgresql+asyncpg://{username}:{token}@{aurora_host}:{port}/{database}"
)

4. Make sure your IAM user or role has the necessary permissions:

json
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "rds-db:connect",
            "Resource": "arn:aws:rds-db:region:account-id:dbuser:resource-id/iam-user"
        }
    ]
}

5. In your Aurora PostgreSQL database, create the IAM user and grant necessary permissions:

sql
CREATE USER your_iam_user WITH LOGIN;
GRANT rds_iam TO your_iam_user;
-- Grant additional permissions as needed
GRANT ALL PRIVILEGES ON DATABASE your_database TO your_iam_user;

If you're running Prefect in a container, you'll need to implement token refresh logic since IAM tokens expire after 15 minutes. Here's a basic example of how to do that:

python
import asyncio
import os
from datetime import datetime, timedelta
from get_aurora_token import get_aurora_token

async def refresh_token():
    while True:
        token = get_aurora_token(
            aurora_host="your-aurora-cluster-endpoint",
            port=5432,
            region="your-aws-region",
            username="your-iam-user"
        )
        
        os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = (
            f"<postgresql+asyncpg://your-iam-user:{token}@your-aurora-cluster-endpoint:5432/your-database>"
        )
        
        # Wait for 14 minutes (tokens expire after 15 minutes)
        await asyncio.sleep(14 * 60)

# Run this in your application startup
asyncio.create_task(refresh_token())

Remember to: - Replace all placeholder values (aurora_host, region, username, etc.) with your actual values - Ensure your AWS credentials are properly configured in the environment where Prefect is running - Consider implementing proper error handling and retry logic in a production environment - Store sensitive information like host names and credentials in environment variables or secrets management Let me know if you need any clarification or run into other issues!

Here are the three ways to properly set the database URL, in order of preference: 1. Using a .env file (Recommended): Create a

.env

file in your project root:

bash
PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>"

2. Setting environment variable before starting the server:

bash
# Linux/Mac
export PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>"
prefect server start

# Windows (Command Prompt)
set PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database>
prefect server start

# Windows (PowerShell)
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>"
prefect server start

3. Using Prefect's settings API:

python
from prefect.settings import Setting
from prefect.server.settings import ServerSettings

# This must be done before the server starts
settings = ServerSettings()
settings.database.connection_url = Setting(
    value="<postgresql+asyncpg://username:token@host:5432/database>"
)

The error you're seeing suggests that Prefect has already initialized with its default SQLite configuration. Here's what's happening: 1. Prefect server starts up 2. It reads the configuration (finds no PostgreSQL URL, defaults to SQLite) 3. Your code sets the environment variable 4. But it's too late - Prefect is already running with SQLite To fix this: 1. Stop all running Prefect processes 2. Set the environment variable using one of the methods above 3. Start Prefect server again If you're running this in a script, make sure to set the environment variable at the very beginning, before importing any Prefect modules:

python
import os
os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = "<postgresql+asyncpg://username:token@host:5432/database>"

# Only after setting the environment variable, import Prefect
from prefect import flow
# ... rest of your code

Also, verify that: - The URL is properly formatted - There are no spaces or unexpected characters in the URL - You can connect to the database using the same credentials with a different tool - The pg_trgm extension is installed in your PostgreSQL database Let me know if you're still having issues after trying these approaches!

For Aurora PostgreSQL with SSL, you'll need to: 1. First, download the Amazon RDS root certificate if you haven't already:

bash
curl -O <https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem>

2. You can provide the SSL certificate in your connection URL using the

sslmode

and

sslrootcert

parameters. Here's how to modify your connection string:

python
import urllib.parse

# Encode the path to your certificate
cert_path = urllib.parse.quote("/path/to/global-bundle.pem")

postgres_url = (
    f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}"
    f"?sslmode=verify-full"
    f"&sslrootcert={cert_path}"
)

os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = postgres_url

3. If you're using a

.env

file, format it like this:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full&sslrootcert=/path/to/global-bundle.pem>

The

sslmode

parameter can be one of: - `verify-full`: Verifies that the server certificate was signed by a trusted CA and that the server hostname matches the certificate - `verify-ca`: Only verifies that the server certificate was signed by a trusted CA - `require`: Requires SSL but doesn't verify the certificate For Aurora,

verify-full

is recommended for maximum security. If you're running in a container, make sure to: 1. Copy the certificate into your container 2. Update the certificate path to point to the location inside the container 3. Mount the certificate file as a volume:

bash
docker run \
  -v /path/to/global-bundle.pem:/certs/global-bundle.pem:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full&sslrootcert=/certs/global-bundle.pem>" \
  prefecthq/prefect:latest

If you need to provide a client certificate and key (though this is less common with Aurora), you can add these parameters:

python
postgres_url = (
    f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}"
    f"?sslmode=verify-full"
    f"&sslrootcert={cert_path}"
    f"&sslcert={client_cert_path}"
    f"&sslkey={client_key_path}"
)

Let me know if you need help with any specific part of the SSL configuration!

For

asyncpg

, we need to use

ssl

parameter instead of

sslmode

. Here's how to set it up: 1. First, create an SSL context that we'll pass to the connection:

python
import ssl
import os

ssl_context = ssl.create_default_context(
    cafile="/path/to/ssl_cert"  # Replace with your cert path
)
ssl_context.verify_mode = ssl.CERT_REQUIRED

2. Then, encode this context as a query parameter:

python
import urllib.parse

# Convert the SSL requirements into a query parameter
ssl_param = urllib.parse.quote("require")

postgres_url = (
    f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}"
    f"?ssl=true"
    f"&ssl_min_protocol_version=TLSv1.2"
)

os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = postgres_url

3. Additionally, you'll need to set these environment variables to point to your SSL certificate:

bash
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME="true"

If you're using a

.env

file:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?ssl=true&ssl_min_protocol_version=TLSv1.2>
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

For Docker deployments:

bash
docker run \
  -v /path/to/ssl_cert:/certs/ssl_cert:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=true&ssl_min_protocol_version=TLSv1.2>" \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/certs/ssl_cert \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true \
  prefecthq/prefect:latest

This configuration should work with Aurora PostgreSQL's SSL requirements. Let me know if you encounter any other issues!

Let's simplify the connection string. For

asyncpg

, we just need to use `ssl=true`:

python
postgres_url = f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}?ssl=true"

And set this in your environment:

bash
# Linux/Mac
export PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=true>"
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"

# Windows (Command Prompt)
set PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?ssl=true>
set PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert

# Windows (PowerShell)
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=true>"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"

Or in your

.env

file:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?ssl=true>
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert

For Docker:

bash
docker run \
  -v /path/to/ssl_cert:/certs/ssl_cert:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=true>" \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/certs/ssl_cert \
  prefecthq/prefect:latest

This simpler configuration should work with Aurora PostgreSQL's SSL requirements. Let me know if you still encounter any issues!

Let's modify the connection string to use the correct

sslmode

parameter. For Aurora PostgreSQL, you'll want to use either

verify-full

(most secure) or

require

(if you just need encryption without certificate verification):

python
postgres_url = (
    f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}"
    "?sslmode=verify-full"
)

Set this in your environment:

bash
# Linux/Mac
export PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full>"
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"

# Windows (Command Prompt)
set PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full>
set PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert

# Windows (PowerShell)
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full>"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"

Or in your

.env

file:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full>
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert

For Docker:

bash
docker run \
  -v /path/to/ssl_cert:/certs/ssl_cert:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?sslmode=verify-full>" \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/certs/ssl_cert \
  prefecthq/prefect:latest

The

sslmode

options mean: - `verify-full`: Verifies that the server certificate was signed by a trusted CA AND that the server hostname matches the certificate - `verify-ca`: Only verifies that the server certificate was signed by a trusted CA - `require`: Requires SSL but doesn't verify the certificate - `prefer`: Uses SSL if available, falls back to non-SSL if not - `allow`: Uses non-SSL if available, falls back to SSL if not - `disable`: Never uses SSL For Aurora PostgreSQL, I recommend using either: -

verify-full

(most secure, recommended for production) -

require

(if you're having issues with certificate verification) Let me know if you still encounter any issues!

For

asyncpg

with SQLAlchemy, we need to use a simpler connection URL and configure SSL through Prefect's settings. Here's how: 1. First, simplify your connection URL to just include the basic connection information:

python
postgres_url = f"postgresql+asyncpg://{username}:{token}@{host}:{port}/{database}"

2. Then set these environment variables to configure SSL:

bash
# Linux/Mac
export PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>"
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"
export PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

# Windows (PowerShell)
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="/path/to/ssl_cert"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

Or in your

.env

file:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database>
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

For Docker:

bash
docker run \
  -v /path/to/ssl_cert:/certs/ssl_cert:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>" \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/certs/ssl_cert \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true \
  prefecthq/prefect:latest

If you need to verify the server's certificate but don't need to verify the hostname (less secure but sometimes necessary), you can set:

bash
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=false

Remember to: 1. Make sure your SSL certificate file path is correct and accessible 2. Set these environment variables BEFORE starting the Prefect server 3. Restart the Prefect server after making these changes Let me know if you still encounter any issues!

Let's configure some additional timeout and connection settings to help with the startup process. Here are the key environment variables you can set:

bash
# Increase database timeout (default is 60 seconds)
export PREFECT_API_DATABASE_TIMEOUT=300

# Increase connection attempt timeout
export PREFECT_API_DATABASE_CONNECTION_TIMEOUT=60

# Configure pool settings
export PREFECT_API_DATABASE_POOL_SIZE=5
export PREFECT_API_DATABASE_MAX_OVERFLOW=10
export PREFECT_API_DATABASE_POOL_TIMEOUT=30

# Configure reconnection settings
export PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=5

Put these in your

.env

file:

bash
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database>
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

# Timeout and connection settings
PREFECT_API_DATABASE_TIMEOUT=300
PREFECT_API_DATABASE_CONNECTION_TIMEOUT=60
PREFECT_API_DATABASE_POOL_SIZE=5
PREFECT_API_DATABASE_MAX_OVERFLOW=10
PREFECT_API_DATABASE_POOL_TIMEOUT=30
PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=5

For Docker:

bash
docker run \
  -v /path/to/ssl_cert:/certs/ssl_cert:ro \
  -e PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database>" \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/certs/ssl_cert \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true \
  -e PREFECT_API_DATABASE_TIMEOUT=300 \
  -e PREFECT_API_DATABASE_CONNECTION_TIMEOUT=60 \
  -e PREFECT_API_DATABASE_POOL_SIZE=5 \
  -e PREFECT_API_DATABASE_MAX_OVERFLOW=10 \
  -e PREFECT_API_DATABASE_POOL_TIMEOUT=30 \
  -e PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=5 \
  prefecthq/prefect:latest

Also, verify these potential issues: 1. Network connectivity: - Ensure your Aurora instance is accessible from your environment - Check security groups and network ACLs - Verify the Aurora endpoint is correct 2. Aurora configuration: - Confirm the IAM user has proper permissions - Check that SSL is properly configured on the Aurora side - Verify the database exists and is accessible 3. SSL certificate: - Ensure the certificate file is readable - Verify it's the correct certificate for your Aurora instance - Check the certificate hasn't expired You can also try starting the server in debug mode to get more information:

bash
prefect server start --log-level=DEBUG

If you're still experiencing issues, could you share: 1. The specific timeout error message you're seeing 2. How long it takes before the timeout occurs 3. Whether you can connect to the Aurora instance using another tool (like

psql

) This will help me provide more targeted assistance!

Let's try these steps to resolve the Windows semaphore timeout: 1. First, modify your Python script to include this at the very beginning (before any Prefect imports):

python
import asyncio
import sys

if sys.platform == 'win32':
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

2. Set these additional environment variables specifically for Windows:

powershell
# PowerShell
$env:PYTHONASYNCIODEBUG=1
$env:PREFECT_API_DATABASE_ECHO=true
$env:PREFECT_SERVER_API_HOST="127.0.0.1"  # Use localhost IP explicitly

Or in Command Prompt:

cmd
set PYTHONASYNCIODEBUG=1
set PREFECT_API_DATABASE_ECHO=true
set PREFECT_SERVER_API_HOST=127.0.0.1

3. Modify your connection URL to include additional parameters:

powershell
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?server_settings={'statement_timeout>': '60000'}&prepared_statement_cache_size=0"

4. Create a

.env

file with all settings combined:

bash
# Base connection settings
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database?server_settings={'statement_timeout>': '60000'}&prepared_statement_cache_size=0
PREFECT_SERVER_API_HOST=127.0.0.1

# SSL settings
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/path/to/ssl_cert
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true

# Timeout settings
PREFECT_API_DATABASE_TIMEOUT=300
PREFECT_API_DATABASE_CONNECTION_TIMEOUT=60
PREFECT_API_DATABASE_POOL_SIZE=5
PREFECT_API_DATABASE_MAX_OVERFLOW=10
PREFECT_API_DATABASE_POOL_TIMEOUT=30
PREFECT_SERVER_SERVICES_TRIGGERS_PG_NOTIFY_RECONNECT_INTERVAL_SECONDS=5

# Debug settings
PYTHONASYNCIODEBUG=1
PREFECT_API_DATABASE_ECHO=true

5. Try starting Prefect server with reduced services:

bash
prefect server start --dev

If you're still experiencing issues, you can try these additional steps: 1. Clear any existing Prefect database:

bash
prefect server database reset

2. Try running with minimal services:

bash
prefect server start --dev --services=api,ui

3. If you're running this in a virtual environment, try creating a fresh one:

bash
python -m venv fresh_env
.\fresh_env\Scripts\activate
pip install -U prefect

4. Check if you can connect to the database using psycopg2 first (which doesn't use async):

python
import psycopg2

conn = psycopg2.connect(
    host="your-host",
    database="your-database",
    user="your-username",
    password="your-token",
    sslmode="verify-full",
    sslcert="/path/to/ssl_cert"
)

If the psycopg2 connection works but Prefect still fails, it suggests the issue is specifically with the async handling on Windows. Let me know if you still encounter issues after trying these solutions!

For Windows, let's make sure the certificate path is properly formatted. Here are a few things to check and try: 1. Use forward slashes (/) instead of backslashes (\) in the path:

powershell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="C:/path/to/certificate.pem"

2. Or escape the backslashes if you need to use them:

powershell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="C:\\path\\to\\certificate.pem"

3. Try using an absolute path:

powershell
# PowerShell - Get absolute path and set it
$certPath = (Resolve-Path ".\certificate.pem").Path
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=$certPath

4. Verify the certificate file exists and is readable:

powershell
# PowerShell
$certPath = $env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE
if (Test-Path $certPath) {
    Write-Host "Certificate file exists at: $certPath"
    Get-Acl $certPath | Format-List
} else {
    Write-Host "Certificate file not found at: $certPath"
}

5. If you're using a

.env

file, make sure to use the correct path format there too:

bash
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=C:/path/to/certificate.pem
# or
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=C:\\path\\to\\certificate.pem

6. You can also try putting the certificate in the same directory as where you're running Prefect and use a relative path:

powershell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="./certificate.pem"

7. Enable debug logging to see more details about the certificate loading:

powershell
$env:PREFECT_LOGGING_LEVEL="DEBUG"

Could you: 1. Share the exact error message you're getting about the certificate? 2. Confirm where your certificate file is located on your system? 3. Try this simple test script to verify the certificate path:

python
import os
import pathlib

cert_path = os.environ.get('PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE')
print(f"Certificate path from env: {cert_path}")
if cert_path:
    path = pathlib.Path(cert_path)
    print(f"Absolute path: {path.absolute()}")
    print(f"File exists: {path.exists()}")
    print(f"Is file: {path.is_file()}")
    if path.exists():
        print(f"File size: {path.stat().st_size} bytes")

This will help us pinpoint exactly where the certificate path issue is occurring!

Let's fix this by ensuring we have the correct certificate chain and settings. Here are the steps: 1. First, download the complete AWS RDS certificate bundle:

bash
curl -O <https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem>

2. Set the environment variables to use this bundle and adjust verification settings:

powershell
# PowerShell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="C:/path/to/global-bundle.pem"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME="true"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_VERIFY_MODE="verify_ca"

Or in your

.env

file:

bash
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=C:/path/to/global-bundle.pem
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_VERIFY_MODE=verify_ca

3. If you're still having issues, you can try these alternative approaches: Option A - Modify your connection URL to include SSL mode:

powershell
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=verify-ca>"

Option B - If the above doesn't work, try with reduced verification (less secure, but useful for testing):

powershell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME="false"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_VERIFY_MODE="verify_ca"

Option C - If you're still having issues, you can temporarily disable hostname verification (NOT recommended for production):

powershell
$env:PREFECT_API_DATABASE_CONNECTION_URL="<postgresql+asyncpg://username:token@host:5432/database?ssl=require>"
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME="false"

4. Verify the certificate bundle:

python
import ssl
import asyncpg

async def test_ssl():
    try:
        conn = await asyncpg.connect(
            user="your_username",
            password="your_token",
            database="your_database",
            host="your_host",
            port=5432,
            ssl=ssl.create_default_context(
                cafile="path/to/global-bundle.pem"
            )
        )
        await conn.close()
        print("Connection successful!")
    except Exception as e:
        print(f"Connection failed: {str(e)}")

import asyncio
asyncio.run(test_ssl())

5. Make sure your Aurora instance: - Has SSL enabled - Is using the correct certificate (check the AWS RDS console) - Has the correct security group rules 6. Complete environment setup (combining all settings):

bash
# Base connection
PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:token@host:5432/database>

# SSL/TLS settings
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_ENABLED=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=C:/path/to/global-bundle.pem
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CHECK_HOSTNAME=true
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_VERIFY_MODE=verify_ca

# Timeout settings
PREFECT_API_DATABASE_TIMEOUT=300
PREFECT_API_DATABASE_CONNECTION_TIMEOUT=60

If you're still experiencing issues, could you: 1. Confirm you're using the AWS RDS

For Aurora PostgreSQL, here are the standard locations where certificates are typically expected: Linux/Unix Systems:

/etc/ssl/certs/rds-ca-global-bundle.pem
~/.postgresql/root.crt
/usr/local/share/ca-certificates/rds-ca-global-bundle.crt

Windows Systems:

%APPDATA%\postgresql\root.crt
C:\Users\YourUsername\AppData\Roaming\postgresql\root.crt
C:\ProgramData\postgresql\root.crt

Here's how to set it up properly: 1. First, download the certificate bundle:

powershell
# PowerShell
Invoke-WebRequest -Uri "<https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem>" -OutFile "global-bundle.pem"

2. Create the appropriate directory and move the certificate:

powershell
# Create PostgreSQL certificate directory if it doesn't exist
$certDir = "$env:APPDATA\postgresql"
New-Item -ItemType Directory -Force -Path $certDir

# Copy the certificate to the standard location
Copy-Item "global-bundle.pem" -Destination "$certDir\root.crt"

3. Set the environment variable to point to this location:

powershell
$env:PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE="$env:APPDATA\postgresql\root.crt"

4. Or in your

.env

file:

bash
PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=%APPDATA%\postgresql\root.crt

5. Verify the certificate is in place:

powershell
if (Test-Path "$env:APPDATA\postgresql\root.crt") {
    Write-Host "Certificate found in standard location"
} else {
    Write-Host "Certificate not found in standard location"
}

6. You can also create a simple test script to verify the certificate:

python
import os
import ssl
import asyncio
import asyncpg

async def test_connection():
    cert_path = os.path.expandvars(r'%APPDATA%\postgresql\root.crt')
    print(f"Using certificate from: {cert_path}")
    
    ssl_context = ssl.create_default_context(
        cafile=cert_path
    )
    
    try:
        conn = await asyncpg.connect(
            user="your_username",
            password="your_token",
            database="your_database",
            host="your-aurora-endpoint",
            port=5432,
            ssl=ssl_context
        )
        await conn.close()
        print("Connection successful!")
    except Exception as e:
        print(f"Connection failed: {str(e)}")

asyncio.run(test_connection())

If you're running in a Docker container, you'll need to: 1. Copy the certificate into the container:

dockerfile
COPY global-bundle.pem /usr/local/share/ca-certificates/rds-ca-global-bundle.crt
RUN update-ca-certificates

2. Set the environment variable in the container:

bash
docker run \
  -e PREFECT_SERVER_DATABASE_SQLALCHEMY_CONNECT_ARGS_TLS_CA_FILE=/usr/local/share/ca-certificates/rds-ca-global-bundle.crt \
  ...
  prefecthq/prefect:latest

Remember to: - Use absolute paths when possible - Ensure the certificate file has the correct permissions - Keep the certificate updated (AWS rotates RDS certificates periodically) - Consider using a secrets manager for production environments Let me know if you need help with any of these steps!

Let's fix the IAM authentication. Here's how to properly generate and use the IAM token: 1. First, make sure you have boto3 installed:

bash
pip install boto3

2. Here's the correct way to generate the token and create the connection URL:

python
import boto3
from sqlalchemy.engine.url import URL
import time

def generate_auth_token(
    username: str,
    host: str,
    port: int,
    region: str = "us-east-1"  # replace with your region
) -> str:
    """Generate an IAM authentication token for Aurora PostgreSQL."""
    rds_client = boto3.client('rds', region_name=region)
    
    token = rds_client.generate_db_auth_token(
        DBHostname=host,
        Port=port,
        DBUsername=username,
        Region=region
    )
    return token

# Your database connection parameters
user = "your_iam_user"
nlb_endpoint = "your_aurora_endpoint"
port = 6160
db_name = "your_database"
region = "your_region"

# Generate the token
token = generate_auth_token(
    username=user,
    host=nlb_endpoint,
    port=port,
    region=region
)

# Create the connection URL
postgres_sql_alchemy_url: str = URL.create(
    drivername="postgresql+asyncpg",
    username=user,
    password=token,  # Use the generated token
    host=nlb_endpoint,
    port=port,
    database=db_name,
    query={
        "ssl": "verify-full"  # or "require" if you want to skip certificate verification
    }
)

3. For a more complete solution that handles token refresh (since tokens expire after 15 minutes):

python
import asyncio
import os
from datetime import datetime, timedelta

class AuroraIAMAuthManager:
    def __init__(
        self,
        user: str,
        host: str,
        port: int,
        database: str,
        region: str
    ):
        self.user = user
        self.host = host
        self.port = port
        self.database = database
        self.region = region
        self.token = None
        self.token_expiry = None

    def get_connection_url(self) -> str:
        """Get a fresh connection URL with a valid token."""
        if self._should_refresh_token():
            self._refresh_token()
        
        return str(URL.create(
            drivername="postgresql+asyncpg",
            username=self.user,
            password=self.token,
            host=self.host,
            port=self.port,
            database=self.database,
            query={
                "ssl": "verify-full"
            }
        ))

    def _should_refresh_token(self) -> bool:
        """Check if token needs refresh (expired or will expire soon)."""
        if not self.token or not self.token_expiry:
            return True
        # Refresh if token will expire in the next 5 minutes
        return datetime.now() + timedelta(minutes=5) >= self.token_expiry

    def _refresh_token(self) -> None:
        """Generate a new token."""
        self.token = generate_auth_token(
            username=self.user,
            host=self.host,
            port=self.port,
            region=self.region
        )
        # Tokens are valid for 15 minutes
        self.token_expiry = datetime.now() + timedelta(minutes=15)

# Usage:
auth_manager = AuroraIAMAuthManager(
    user="your_iam_user",
    host="your_aurora_endpoint",
    port=6160,
    database="your_database",
    region="your_region"
)

# Get the connection URL with a fresh token
connection_url = auth_manager.get_connection_url()
os.environ["PREFECT_API_DATABASE_CONNECTION_URL"] = connection_url

4. Make sure your IAM user has the correct permissions: ```json { "Version