Updating only one function in serverless - aws-cloudformation

Question

I have a serverless.yml file with 3 functions.
When I run serverless deploy it updates all 3 functions, which takes a lot of time.
Is there a way I can update just 1 function without affecting the rest of the stack (i.e., not updating the cloud stack)?
I tried serverless deploy -f functionA but it seems to still process and upload the other functions.
service: myrestapi
provider:
name: aws
region: 'us-east-1'
runtime: nodejs14.x
functions:
functionA:
handler: functions/functionA.handler
memorySize: 256
functionB:
handler: functions/functionB.handler
memorySize: 128
functionC:
handler: functions/functionC.handler
memorySize: 128

Answer 1

why do you think it's deploying the full stack and not only the function ?
Output says it's only deploy's the function A, isn't it ?
$ serverless deploy
Running "serverless" from node_modules
Deploying myrestapi to stage dev (us-east-1)
✔ Service deployed to stack myrestapi-dev (128s)
functions:
functionA: myrestapi-dev-functionA (30 MB)
functionB: myrestapi-dev-functionB (30 MB)
functionC: myrestapi-dev-functionC (30 MB)
$ serverless deploy -f functionA
Running "serverless" from node_modules
Deploying function functionA to stage dev (us-east-1)
✔ Function code deployed (17s)
Configuration did not change. Configuration update skipped. (17s)
Perhaps, you're looking for
package:
individually: true
and include only the files needed for your function
service: myrestapi
provider:
name: aws
region: 'us-east-1'
runtime: nodejs14.x
package:
individually: true
patterns:
- '!node_modules/**'
- '!functions/**'
functions:
functionA:
handler: functions/functionA.handler
memorySize: 256
package:
patterns:
- 'node_modules/node-fetch/**'
- functions/functionA.js
functionB:
handler: functions/functionB.handler
memorySize: 128
package:
patterns:
- functions/functionB.js
functionC:
handler: functions/functionC.handler
memorySize: 128
package:
patterns:
- 'node_modules/node-fetch/**'
- functions/functionC.js