(cli): cdk watch should stop after synth and not move to deploy if more changes are made during synth

[Dzhuneyt]

Describe the feature

If Change A is being queued and starts deployment by the cdk watch command, a second change (Change B) coming in during that deployment process has to wait for the WHOLE synth + deploy cycle to complete, before Change B starts to be deployed. We could easily skip the deploy step here and implement a killswitch that skips the deploy after the synth has completed IF there was another change pushed to the queue during the synth phase.

Use Case

Iterating (live development) on a larger CDK project with multiple Stacks and a large number of resources to be synthesized

Proposed Solution

When the cdk watch command is left running in a terminal, and I make a change inside the project, to oversimplify - it goes through a two-step process: cdk synth and cdk deploy. Let's assume that for a relatively large project with multiple stacks both of these steps take 1 minute each.

When cdk watch starts the process, the whole 2 minutes are pretty much non-interruptable and any chance I make within these 2 minutes are queued and will start deployment exactly 2 minutes after the first change. Assuming I queue a second change at the 25 seconds mark, after the first one started the non-interruptable process - I will have to wait at least 35 seconds more for the two-step process to complete, before the second change starts deploying.

My suggested solution is to quickly check after the cdk synth if the deployment (second step) is still valid or is now stale and should be skipped (because another change has been queued). This essentially means that the second change that I did in the 25 seconds mark, will have to wait for just 5 more seconds for the cdk synth to complete, and cdk deploy will be skipped.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.122.0 (build 7e77e02)

Environment details (OS name and version, etc.)

MacOS

[pahud]

Thank you for the feedback. This makes sense to me.