Feature request: ability to change HeadNode (Master node) instance type

[gns-build-server]

I noticed that even as of Parallelcluster 3.5, the ability to change the instance type (even just changing the size, within the same instance class) of the HeadNode is still not a thing one can update with a pcluster update. "If you need this change, please consider creating a new cluster instead of updating the existing one" is such a silly answer...

...since it's so easy and foolproof already to do this with the workaround we've been using since Parallelcluster 2.X:

1) Stop head node (can even do this in the Parallelcluster GUI now) 2) Go to instance in AWS EC2 console or CLI (can even get to console by clicking instance in the Parallelcluster GUI now) 3) Change instance type in EC2 console or CLI 4) Start head node (can even do this in the Parallelcluster GUI now)

What's especially funny is that after doing this, the Parallelcluster GUI even reports the correct instance type!

[chenwany]

Hello @gns-build-server , thanks for your feedback, I'm marking this as feature request so to be discussed by our team.

[elduds]

Seems this is still an issue in v3.8.0, adding my +1

❯ pcluster version
{
  "version": "3.8.0"
}

❯ pcluster update-cluster -n energy-elec02 -c energy-elec02.yaml --dryrun true

{
  "message": "Update failure",
  "updateValidationErrors": [
   {
     "parameter": "HeadNode.InstanceType",
     "requestedValue": "g4dn.4xlarge",
     "message": "Update actions are not currently supported for the 'InstanceType' parameter. Restore 'InstanceType' value to 'g4dn.xlarge'. If you need this change, please consider creating a new cluster instead of updating the existing one.",
     "currentValue": "g4dn.xlarge"
   }
  ],