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Does Blueprint supports add hostgroups post cluster create?


Blueprint supports SLAVE node expansion through "add host" API. We could provide blueprint and hostgroup name to add host API and the API takes care of replicating hostgroup components (from corresponding Blueprint) in the new set of hosts. In scenario where if only DATANODE" needs to be expanded, it is not possible unless the BP has a hostgroup that has only "DATANODE" component.




This article should help grow cluster after install


Thanks Ali Bajwa. My question is how one could possibly mutate blueprint to add hostgroups dynamically instead of playiing with only fixed set created duirng cluster create step.

Expert Contributor

@Vijay Srinivasaraghavan, Once a Blueprint is posted, the document is immutable, so there is no way currently to add a host group to a Blueprint.

That being said, I believe you can obtain the same effect by trying the following:

  1. POST a Blueprint that contains: the host groups used in your cluster, and an extra host group that only contains the "DATANODE" component (and perhaps any required dependencies).
  2. POST the Cluster Creation template as normal, but do not map any hosts to the host group that only contains "DATANODE" components.
  3. When necessary, use the "Add Host" API to add new hosts based on the "extra" host group.
  4. As long as there are no configuration dependencies specified that point to the host group that is not initially used, this should work fine. Usually, configuration dependencies would mean things such as %HOSTGROUP% references that refer to the "extra" host group, which shouldn't be necessary anyway.

While this approach doesn't allow you to add host groups dynamically, it should allow you to have more fine-grained control over the types of components that are deployed during a scale-out operation.


@rnettleton, I was following the same steps that you have mentioned but if we go with this approach, we need to come up with all possible hostgroup (component maping) combinations ahead of time. I was trying to find a way to overcome by adding new hostgroup to existing BP (not modifying any of the existing BP structure). May be we shall consider this as a feature request?

New Contributor

I understand this is still around but is it being tracked in jira? Can't find the related issue for dynamically updating a blueprint