Ref is used to reference other resources or parameters in your template. Depending on the Resource it will return what data is typically needed the most from that resource. For example for a S3 Bucket it returns the bucket name, for an ACM Certificate it will return the ARN.

What does REF do in CloudFormation?

The intrinsic function Ref returns the value of the specified parameter or resource. When you specify a parameter's logical name, it returns the value of the parameter. When you specify a resource's logical name, it returns a value that you can typically use to refer to that resource, such as a physical ID.

What is difference between ref and GetAtt?

GetAtt is essentially the same as the 2nd function of Ref above, it also returns an attribute of the resource that you created within your resource, but while ref returns only a default attribute, GetAtt allows you to choose from different attributes to return.

How do I get an SNS Arn?

1 Answer. In your CloudFormation template, if you simply reference your SNS topic, then you'll get the ARN. So you can use that as input to your nested CloudFormation template.

What is FN :: GetAtt?

The Fn::GetAtt intrinsic function returns the value of an attribute from a resource in the template. For more information about GetAtt return values for a particular resource, refer to the documentation for that resource in the Resource and property reference.

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28 related questions found

Is it rollback<UNK>Complete?

This happens when stack creation fails. By default the stack will remain in place with a status of ROLLBACK_COMPLETE . This means it's successfully rolled back (deleted) all the resources which the stack had created. The only thing remaining is the empty stack itself.

Is SNS a Kafka?

Apache Kafka is a distributed publish-subscribe messaging system. And SNS is also pub/sub system. My goal is to use some queue messaging system on AWS with application that will be distributed over few servers (By the way the main language is Python).

What is the use of SNS in AWS?

Amazon SNS enables you to send messages or notifications directly to users with SMS text messages to over 200 countries, mobile push on Apple, Android, and other platforms or email (SMTP).

How do I start a new SNS topic?

Step 1: Create a topic

1. Sign in to the Amazon SNS console .
2. In the left navigation pane, choose Topics.
3. On the Topics page, choose Create topic.
4. By default, the console creates a FIFO topic. ...
5. In the Details section, enter a Name for the topic, such as MyTopic .
6. Scroll to the end of the form and choose Create topic.

What is sub in CloudFormation?

Sub is just a string, we're using the short form of the function still. This allows us to include parameters, resources, or Pseudo Parameters such as AWS::Region right in the string. These will be substituted for their values by the CloudFormation service.

How do you get target group Arn in CloudFormation?

If the Target Group was created in Cloudformation, it's easy enough to get the ARN output by using ! Ref myTargetGroup . If the Target Group was created in another CF stack, try Exporting the Target Group ARN and use Fn::ImportValue when creating the ECS Service to input the Target Group ARN.

Which section of a CloudFormation template does not allow for conditions?

According to the docs, Conditions should be used at the top level of the resource you want to conditionally create. Putting a Condition inside the Instance UserData section isn't supported. To use Conditions in your situation, you'd want separate Resources conditionally created based on the Parameter.

What can the ref identifier in a cloud formation template file be used to reference?

You can use the Ref function to refer to an identifying property of a resource. Frequently, this is the physical name of the resource; however, sometimes it can be an identifier, such as the IP address for an AWS::EC2::EIP resource or an Amazon Resource Name (ARN) for an Amazon SNS topic.

What is AWS :: NoValue?

AWS::NoValue

Removes the corresponding resource property when specified as a return value in the Fn::If intrinsic function. For example, you can use the AWS::NoValue parameter when you want to use a snapshot for an Amazon RDS DB instance only if a snapshot ID is provided.

What happens when you delete a CloudFormation stack?

During deletion, CloudFormation deletes the stack but does not delete the retained resources. Retaining resources is useful when you cannot delete a resource, such as a non-empty S3 bucket, but you want to delete the stack.

Is SNS push or pull?

SNS is a distributed publish-subscribe system. Messages are pushed to subscribers as and when they are sent by publishers to SNS. SQS is distributed queuing system. Messages are not pushed to receivers.

Is SNS reliable?

Since Amazon SNS is both highly reliable and scalable, it provides significant advantages to developers who build applications that rely on real-time events.

Is SNS asynchronous?

Several AWS services, such as Amazon Simple Storage Service (Amazon S3) and Amazon Simple Notification Service (Amazon SNS), invoke functions asynchronously to process events. When you invoke a function asynchronously, you don't wait for a response from the function code.

What is Cafca?

Kafka is an open source software which provides a framework for storing, reading and analysing streaming data. Being open source means that it is essentially free to use and has a large network of users and developers who contribute towards updates, new features and offering support for new users.

Is Amazon SQS like Kafka?

kafka is Apache product and SQS is Amazon product, high level they both are used to store data for a defined time.

Is RabbitMQ pub-sub?

2 Answers. Conceptually, RabbitMQ is both: point-to-point as well as pub-sub. You can register your listener application to the topic of an RabbitMQ exchange and receive all messages published to that Topic. So that is clearly 'pub-sub'.

What is rollback in AWS?

Rollback triggers enable you to have AWS CloudFormation monitor the state of your application during stack creation and updating, and to roll back that operation if the application breaches the threshold of any of the alarms you've specified.

What is AWS CloudFormation conditions?

AWS CloudFormation creates entities that are associated with a true condition and ignores entities that are associated with a false condition. Use the Condition key and a condition's logical ID to associate it with a resource or output. To conditionally specify a property, use the Fn::If function.

How can you deploy a lambda serverless application?

You can deploy your application manually using AWS SAM command line interface (CLI) commands. You can also automate the deployments of your application using a continuous integration and continuous deployment (CI/CD) system.