copy_env.rb

require 'json'

# Usage examples:
# Copy from an EB environment to another EB environment:
#   copy_env({name: "abc-eb-app", source: :eb, profile: "def"}, {name: "def-eb-app", source: :eb, profile: "def"})
#
# Copy from a Heroku app to an EB environment:
#   copy_env({name: "your-heroku-app", source: :heroku}, {name: "def-eb-app", source: :eb, profile: "def"})
def copy_env(from, to)
  from_name    = from[:name]
  from_source  = from[:source] || :eb
  from_profile = from[:profile]

  to_name    = to[:name]
  to_profile = to[:profile]

  env_vars = case from_source
             when :heroku
               EnvVars.from_heroku(from_name)
             else
               EnvVars.from_eb(from_name, from_profile)
             end

  env_vars.set_eb_env!(to_name, to_profile)
end

class EnvVars
  def initialize(vars)
    @vars = vars.map { |k, v| EnvVar.new(k, v) }
  end

  def self.from_eb(env_name, profile = nil)
    cmd = "eb printenv #{env_name}"
    cmd += " --profile #{profile}" if profile
    env_lines = `#{cmd}`.split("\n").select { |v| v =~ / = / }
    vars = env_lines.map { |v| v.strip.split(" = ") }
    EnvVars.new(vars)
  end

  def self.from_heroku(app)
    json_str = `heroku config -j --app #{app}`
    config = JSON.parse(json_str)
    vars = config.to_a
    EnvVars.new(vars)
  end

  def set_eb_env(env_name, profile = nil)
    vars = @vars.map { |v| "\"#{v}\"" }
    cmd = "eb setenv #{vars.join(" ")} -e #{env_name}"
    cmd += " --profile #{profile}" if profile
    cmd
  end

  def set_eb_env!(env_name, profile = nil)
    cmd = set_eb_env(env_name, profile)
    puts cmd
    `#{cmd}`
  end
end

class EnvVar
  def initialize(name, value)
    @name = name
    @value = value
  end

  def to_s
    "#{@name}=#{@value}"
  end
end