06. CF Resources

Resources are the core of a CloudFormation template. They represent the different AWS Components that will be created. These can reference each other inside the same template.

• DependsOn: very useful to draw a dependency between two resources, like only create a ECS cluster after creating a ASG.
• DeletionPolicy: protect resources from being deleted even if the stack is deleted.
• UpdateReplacePolicy: protects resources from being replaced during a CF update.
• CreationPolicy.
• UpdatePolicy.

It allows to specify that the creation of a specific resource follows another. When added to ar esource, that resource is created only after the creation of the resource specified in the DependsOn.

This is automatically applied when using !Ref or !GetAtt.

Control what happens when the CF template is deleted or when a resource is removed directly from a template. You have this options:

• DeletionPolicy=Retain: specify on resources to preserve/backup in case of CF deletes.
• DeletionPolicy=Snapshot: storage like resources, like EBS Volume, ElastiCache, etc.
• DeletionPolicy=Delete: it’s the default one.