​Worker ​Isolation

How to configure worker isolation in Kestra.

When dealing with multiple teams, you can add extra security measures to your Kestra instance to isolate access so that there is no shared file system, only certain plugins can create worker threads, and script tasks are isolated.

Java security

By default, Kestra uses a shared worker to handle workloads. This is fine for most use cases. However, when using a shared Kestra instance across multiple teams, this can allow people to access temporary files created by Kestra with powerful tasks like Groovy, Jython, and more. This is because the worker shares the same file system.

You can use the following to opt-in to real isolation of file systems using advanced Kestra EE Java security:

kestra:
  ee:
    javaSecurity:
      enabled: true
      forbiddenPaths:
        - /etc/
      authorizedClassPrefix:
        - io.kestra.plugin.core
        - io.kestra.plugin.gcp

To only limit access to certain plugins on a Worker without requiring file path protection, you can also consider configuring Kestra with Allowed & Restricted plugins.

kestra.ee.java-security.forbidden-paths

This is a list of paths on the file system that the Kestra Worker will be forbidden to read or write to. This can help to protect Kestra configuration files and ensure security for audits and compliance. With this property configured, you can reduce the amount of directories that a Worker can access such as protecting access to the folders where global Kestra configuration or ~/.aws/credentials are stored.

kestra.ee.java-security.authorized-class-prefix

This is a list of classes that can create threads. Here you can set a list of prefixes (namespace) classes that will be allowed. All others will be refused.

For example, GCP plugins will need to create a thread in order to reach the GCP API. Since this whole plugin is deemed safe, you can whitelist it.

kestra.ee.java-security.forbidden-class-prefix

This is a list of classes that can't create any threads. Other plugins will be authorized.

kestra:
  ee:
    javaSecurity:
      enabled: true
      forbiddenClassPrefix:
        - io.kestra.plugin.scripts

Scripting isolation

You can provide global plugin defaults using the kestra.plugins.defaults configuration. Those will be applied to each task on your cluster if a property is not defined on flows or tasks. Plugin defaults ensure a property is defined at a default value for these tasks.

kestra:
  plugins:
    defaults:
    - type: io.kestra.plugin.core.log.Log
      values:
        level: ERROR

For Bash tasks and other script tasks in the core, we advise you to force io.kestra.plugin.scripts.runner.docker.Docker isolation and to configure global cluster pluginDefaults:

kestra:
  tasks:
    defaults:
      - type: io.kestra.plugin.scripts.shell.Commands
        forced: true
        values:
          containerImage: ubuntu:latest
          taskRunner:
            type: io.kestra.plugin.scripts.runner.docker.Docker

Forced plugin defaults:

• ensure a property is set globally for a task, and no task can override it
• are critical for security and governance—for example, to enforce Shell tasks to run as Docker containers.