a bit o' spruce, from http://play.spruce.cf

spruce.json

{"flavor":"1.29.0","prune":["meta"],"env":["HOME=/home/user"],"cherry_pick":[],"yaml":[{"filename":"original_bosh.yml","contents":"--- # original_bosh.yml\naddons:\n- jobs:\n  - name: bosh-dns-aliases\n    properties:\n      aliases:\n      - domain: _.cell.service.cf.internal\n        targets:\n        - deployment: ((deployment_name))\n          domain: bosh\n          instance_group: diego-cell\n          network: ((cf_runtime_network))\n          query: _\n        - deployment: ((deployment_name))\n          domain: bosh\n          instance_group: windows2012R2-cell\n          network: ((cf_runtime_network))\n          query: _\n        - deployment: ((deployment_name))\n          domain: bosh\n          instance_group: windows2016-cell\n          network: ((cf_runtime_network))\n          query: _\n        - deployment: ((deployment_name))\n          domain: bosh\n          instance_group: isolated-diego-cell\n          network: ((cf_runtime_network))\n          query: _\n\n\n"},{"filename":"group_params.yml","contents":"--- # group_params.yml\niso_group:\n  name: iso-group\n  azs:\n  - z1\n  vm_type: small-highmem\n  vm_extensions:\n  - 100GB_ephemeral_disk\n  network_name: ((cf_runtime_network))\n  stemcell: test\n\n"},{"filename":"final_replace.yml","contents":"--- # final_replace.yml\ninstance_groups:\n- name: (( grab iso_group.name ))\n  azs: (( grab iso_group.azs || \"[]\" ))\n  instances: (( grab iso_group.instances || 1 ))\n  vm_type: (( grab iso_group.vm_type || \"minimal\" ))\n  vm_extensions: (( grab iso_group.vm_extensions || \"[]\" ))\n  stemcell: (( grab iso_group.stemcell || \"default\" ))\n  networks:\n  - name: (( grab iso_group.network_name || \"default\" ))\n\naddons:\n- jobs:\n  - name: bosh-dns-aliases\n    properties:\n      aliases:\n      - domain: _.cell.service.cf.internal\n        targets:\n        - ((append))\n        - deployment: ((deployment_name))\n          domain: bosh\n          instance_group: (( grab iso_group.name ))\n          network: (( grab iso_group.network_name || \"default\"))\n          query: _\n"},{"filename":"file4.yml","contents":"--- #removal\niso_group: (( empty map ))\n\n\n"}],"skip_eval":false,"fallback_append":false,"go_patch":false,"debug":false,"trace":false}