render yaml template and concat

render

#!/bin/bash

# EXAMPLE:
# $ cat production.env
#
# DB_HOST="foo=bar bas=10"
# DB_PORT=5432
# DB_PASSWORD=$DB_PASSWORD
#
# $ cat test.yaml
# ...
#   - name: "DB_HOST"
#     value: "$DB_HOST"
#   - name: "DB_PORT"
#     value: "$DB_PORT"
#   - name: "DB_PASSWORD"
#     value: "$DB_PASSWORD"
#
# you run render and it will expand `$DB_HOST` to the env-var `DB_HOST` and `$DB_PORT` to the one described as `5432`:
#
# $ DB_PASSWORD=foobarbaz render production.env test.yaml                         
# - name: "DB_HOST"
#   value: "foo=bar bas=10"
# - name: "DB_PORT"
#   value: "5432"
# - name: "DB_PASSWORD"
#   value: "foobarbaz"

if (($# < 2)); then 
  echo "usage: 
  render production.env YAML_FILE_PATHS
example:
  render config_production.txt service.yaml loadbalancer.yaml db.yaml
"
  exit 1
fi

for ((i=2; i<=$#; i++))
do
  (set -a; source $1; set +a; envsubst < ${!i})
  printf "\n---\n"
done