Bootstrap Actions is a new feature in Amazon Elastic MapReduce that provides users a way to run custom set-up prior to the execution of their job flow. Bootstrap Actions can be used to install software or configure instances before running your job flow. You can write a Bootstrap Action script in any language including among others Bash, Perl, Python, Ruby, C++, or Java. There are several pre-defined Bootstrap Actions available. Please refer to the Developer’s Guide for details on how to use Bootstrap Actions.