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

spruce.json

{"flavor":"1.14.0","prune":["meta"],"env":["HOME=/home/user"],"cherry_pick":[],"yaml":[{"filename":"file1.yml","contents":"meta:\n  job_definition:\n    instances: 1\n    update:\n      serial: false\n      max_in_flight: 4\n    \ninstance_groups:\n- .: (( inject meta.job_definition ))\n- xxx: yyy\n- .: (( inject meta.job_definition ))\n\n\n\n"}],"skip_eval":false,"fallback_append":false,"go_patch":false,"debug":false,"trace":false}