String Interpolation in YAML

string_interpolation_in_yaml.rb

require 'yaml'
ENV.update('foo' => 'FOO')
ENV.update('bar' => 'BAR')
ENV.update('baz' => 'BAZ')
p YAML.load(<<EOS)
---
foo: !ruby/string #{ENV['foo']}
bar: !str #{ENV['bar']}
baz: ! #{ENV['baz']}
EOS

# => {"foo"=>"FOO", "bar"=>"BAR", "baz"=>"BAZ"}