Configuration settings to define actions and arguments

The following configuration settings are used to define HeadNode / CustomActions / OnNodeStart & OnNodeConfigured & OnNodeUpdated and Scheduling / CustomActions / OnNodeStart & OnNodeConfigured actions and arguments.

HeadNode:
  [...]
  CustomActions:
    OnNodeStart:
      # Script URL. This is run before any of the bootstrap scripts are run
      Script: s3://amzn-s3-demo-bucket/on-node-start.sh
      Args:
        - arg1
    OnNodeConfigured:
      # Script URL. This is run after all the bootstrap scripts are run
      Script: s3://amzn-s3-demo-bucket/on-node-configured.sh
      Args:
        - arg1
    OnNodeUpdated:
      # Script URL. This is run after the head node update is completed.
      Script: s3://amzn-s3-demo-bucket/on-node-updated.sh
      Args:
        - arg1
  # Bucket permissions
  Iam:
    S3Access:
      - BucketName: bucket_name
        EnableWriteAccess: false
Scheduling:
  Scheduler: slurm
   [...]
  SlurmQueues:
    - Name: queue1
      [...]
      CustomActions:
        OnNodeStart:
          Script: s3://amzn-s3-demo-bucket/on-node-start.sh
          Args:
            - arg1
        OnNodeConfigured:
          Script: s3://amzn-s3-demo-bucket/on-node-configured.sh
          Args:
            - arg1
      Iam:
        S3Access:
          - BucketName: bucket_name
            EnableWriteAccess: false

Using the Sequence setting (added in AWS ParallelCluster version 3.6.0):

HeadNode:
  [...]
  CustomActions:
    OnNodeStart:
      # Script URLs. The scripts are run in the same order as listed in the configuration, before any of the bootstrap scripts are run.
      Sequence:
        - Script: s3://amzn-s3-demo-bucket/on-node-start1.sh
          Args:
            - arg1
        - Script: s3://amzn-s3-demo-bucket/on-node-start2.sh
          Args:
            - arg1
        [...]
    OnNodeConfigured:
      # Script URLs. The scripts are run in the same order as listed in the configuration, after all the bootstrap scripts are run.
      Sequence:
        - Script: s3://amzn-s3-demo-bucket/on-node-configured1.sh
          Args:
            - arg1
        - Script: s3://amzn-s3-demo-bucket/on-node-configured2.sh
          Args:
            - arg1
        [...]
    OnNodeUpdated:
      # Script URLs. The scripts are run in the same order as listed in the configuration, after the head node update is completed.
      Sequence:
        - Script: s3://amzn-s3-demo-bucket/on-node-updated1.sh
          Args:
            - arg1
        - Script: s3://amzn-s3-demo-bucket/on-node-updated2.sh
          Args:
            - arg1
        [...]
  # Bucket permissions
  Iam:
    S3Access:
      - BucketName: bucket_name
        EnableWriteAccess: false
Scheduling:
  Scheduler: slurm
   [...]
  SlurmQueues:
    - Name: queue1
      [...]
      CustomActions:
        OnNodeStart:
          # Script URLs. The scripts are run in the same order as listed in the configuration, before any of the bootstrap scripts are run
          Sequence:
            - Script: s3://amzn-s3-demo-bucket/on-node-start1.sh
              Args:
                - arg1
            - Script: s3://amzn-s3-demo-bucket/on-node-start2.sh
              Args:
                - arg1
            [...]
        OnNodeConfigured:
          # Script URLs. The scripts are run in the same order as listed in the configuration, after all the bootstrap scripts are run
          Sequence:
            - Script: s3://amzn-s3-demo-bucket/on-node-configured1.sh
              Args:
                - arg1
            - Script: s3://amzn-s3-demo-bucket/on-node-configured2.sh
              Args:
                - arg1
            [...]
      Iam:
        S3Access:
          - BucketName: bucket_name
            EnableWriteAccess: false

The Sequence setting is added starting with AWS ParallelCluster version 3.6.0. When you specify Sequence, you can list multiple scripts for a custom action. AWS ParallelCluster continues to support configuring a custom action with a single script, without including Sequence.

AWS ParallelCluster doesn't support including both a single script and Sequence for the same custom action. For example, AWS ParallelCluster fails if you specify the following configuration.

[...]
  CustomActions:
    OnNodeStart:
      # Script URL. This is run before any of the bootstrap scripts are run
      Script: s3://amzn-s3-demo-bucket/on-node-start.sh
          Args:
            - arg1
      # Script URLs. The scripts are run in the same order as listed in the configuration, before any of the bootstrap scripts are run.
      Sequence:
        - Script: s3://amzn-s3-demo-bucket/on-node-start1.sh
          Args:
            - arg1
        - Script: s3://amzn-s3-demo-bucket/on-node-start2.sh
          Args:
            - arg1
[...]