Release Note

Written by Rucha Kulkarni in

on May 19th, 2026

Nextflow Head Instance Customization and Enhanced Execution Controls

General 

This release introduces customizable compute resources for Nextflow head (executor) instances at both the app and task level. You can now right-size the head job separately from worker instances, improving reliability and cost efficiency for complex Nextflow workflows while preserving backward compatibility for existing apps. 

New Features 

• Customizable Head Job Instance for Nextflow Tasks : Nextflow tasks now support a dedicated “Nextflow Head Instance type” configuration under Task → Execution settings. When “Nextflow Multi-Instance Execution” is enabled, you can select a custom head instance type and adjust attached storage. App-level defaults can be defined in the app YAML configuration or managed via the public API, with changes reflected bidirectionally between YAML and the UI. 

Improvements 

• Right-sized head job resources: Workflows with heavy orchestration logic can now run on more capable head instances, reducing failures caused by out-of-memory conditions or controller overload. Lighter workloads can use smaller instances to reduce cost. 
• Predictable default behavior: If only an app-level head instance is configured, it serves as the default. If both app-level and task-level are configured, the task-level takes precedence. Existing apps without head instance configuration continue using platform defaults. 
• Clearer UI terminology: The existing “Instance type” for worker tasks is now labeled “Nextflow Worker Instance type” to clearly distinguish worker resources from head job configuration.
• Network restriction compatibility: For projects with network restrictions enabled, the Nextflow head instance now also honours the project’s network access policy, consistent with worker instance behavior.
• Division name in task notifications: Addition of Division name in mail notifications for tasks making it easier for users in multi-division organizations to quickly identify and prioritize relevant task notifications 

Resources 

If you have questions or experience issues, please contact your Velsera Seven Bridges representative or email support@velsera.com.