Hello,
I have been working as a Devops Engineer with 7 + years of experience,we are using Terraform, packer , Ansible and docker as a combo to build our infrastructure, our whole infra (100+ servers)is dynamic which can build in 15 min.
Coming to your requirements, we are also using a similar setup Filebeat-> logstash -> elastic search -> kibana.
I can help you to build self provisioned,scalable infrastructure for ELK using Terraform..
Thanks