Recently I came across a situation where am building AWS infrastructure using terraform to setup a clustered environment for some applications. Thing is when I apply terraform scripts it builds all the necessary modules and spins multiple instances altogether and then finishes. This may be meant to do like this and there is nothing to blame anyways terraform works greatly to build such infra.
When I'm trying to setup such infra to deploy an application in a clustered way, here am using a configuration management tool. While building ec2 instances CM scripts gets invoked and configured accordingly. Problem comes when there is some dependency on the modules.
Consider a scenario that 2(A & B) components are part of Autoscale group and 2(C & D) components are normal ec2-instances. Here if I wish to build A first and then C since C instance got dependency on A which has to be fully configured first or vice versa, how can I control the order in which terraform helps me to achieve this.
Please can someone helps me achieving it.
Thanks in advance
You can use the depends_on parameter. Resources can be made explicitly dependant on other resources. Terraform will in turn only build the resource once dependent resources have provisioned successfully.
https://www.terraform.io/intro/getting-started/dependencies.html