DependsOn Attribute in CloudFormation:

The DependsOn attribute in AWS CloudFormation ensures that one resource is created only after another resource has been successfully created. In this case, it ensures that the EC2 instance is fully launched before the custom resource (the Lambda function) is executed.

Steps:

Update the CloudFormation template to include the DependsOn attribute for the custom resource.

Ensure that the custom resource references the EC2 instance.

Resources:

MyEC2Instance:

Type: AWS::EC2::Instance

Properties:

# EC2 properties

MyCustomResource:

Type: Custom::MyCustomResource

DependsOn: MyEC2Instance

Properties:

ServiceToken: !GetAtt MyLambdaFunction.Arn

# Other properties

AWS CloudFormation DependsOn Attribute