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5: Updating CF Stacks

·1 min

How does one update a CF stack?

(Say we need to size up our ec2 instance)

  1. Submit updated template
  2. CF compares changes
  3. Only changed resources are changed


  1. “Direct Update” (just go for it)
  2. “Change set” (Gives ability to do a dry-run / preview)

Potential update behaviors?

(Varies by resource type)

1. Update w/ no interruption

  • Updates resource w/o disrupting ops nor physical ID
  • E.g. Instance profile

2. Update w/ some interruption

  • Updates w/ some interruption. Physical ID retained
  • E.g. HostId

3. Replacement

  • Total recreation / new physical ID.
  • E.g. availability zone

Direct changes or change sets?

  • Change sets are good for prod
  • Direct is fine for dev or test

How to utilize update behaviors?

  • Dictates how to modify resources
  • Don’t do a full “replacement” if you need to retain physical ID label