How do I determine whether to use a bootstrap action or a step on an Amazon EMR cluster?

Resolution

To install additional software on an Amazon EMR cluster, use bootstrap actions. To submit work to an Amazon EMR cluster or process data, use steps.

Use bootstrap actions

To use bootstrap actions, take one of the following actions:

• To create bootstrap actions, see Create bootstrap actions to install additional software. If a bootstrap action fails, then the cluster doesn't start. For more information, see Understanding the cluster lifecycle.
• To update cluster nodes after Amazon EMR configures applications, see How do I update all Amazon EMR nodes after the bootstrap phase?
• To configure bootstrap actions to run conditionally based on instance-specific values in the instance.json or job-flow.json files, see Conditionally run a bootstrap action.

Note: For Amazon EMR 2.x and 3.x releases, bootstrap actions run after you install core services. Later Amazon EMR releases don't support most predefined bootstrap actions for Amazon EMR AMI versions 2.x and 3.x.

Use steps

Steps contain Hadoop jobs that transfer or process data. Steps also process submitted data, and send the processed data to a specified location.

To use steps, take one of the following actions:

• To submit work, see Submit work to a cluster.
• To process data, see Running steps to process data.
• For Amazon EMR versions 5.28.0 and later, steps can run in parallel. For Amazon EMR versions that are earlier than 5.28.0, steps complete their work sequentially. For more information, see Considerations for running multiple steps in parallel.
• To configure the action that a step takes when the action fails, use the ActionOnFailure action. For more information, see StepConfig.
• To cancel pending and running steps, see Canceling steps.