AWS Boto3 BASE64 encoding error thrown when invoking client.request_spot_instances method

Question

I am trying to submit a request for an EC2 SPOT instance using boto3 (Environment Python 3.5,Windows 7). I need to pass the UserData parameter for running initial scripts.

The error I get is File "C:\Users...\Python\Python35\lib\site-packages\botocore\client.py", line 222, in _make_api_call raise ClientError(parsed_response, operation_name) botocore.exceptions.ClientError: An error occurred (InvalidParameterValue) when calling the RequestSpotInstances operation: Invalid BASE64 encoding of user data Code

I am following this documentation https://boto3.readthedocs.io/en/latest/reference/services/ec2.html#EC2.Client.request_spot_instances

If I take the UserData parameter out – everything works well.

I have tried different ways to pass the parameter but I end up with the same.similar errors.

Boto 3 Script

    client = session.client('ec2')

    myparam = str(base64.b64encode(bytes('yum install -y php', 'utf-8')))

    response = client.request_spot_instances(
    SpotPrice='0.4',
    InstanceCount=1,
    Type='one-time',
    LaunchSpecification={
    'ImageId': 'ami-xxxxxx',
    'KeyName': 'xxxxx',
    'InstanceType': 't1.micro',
    'UserData': myparam,
    'Monitoring': {
    'Enabled': True
    }
    })

Answer 1

I think you shouldn't convert your base64 string to str. Are you using Python 3?

Replace:

myparam = str(base64.b64encode(bytes('yum install -y php', 'utf-8')))

By:

myparam = base64.b64encode(b'yum install -y php').decode("ascii")