Executors

Executors are the core plugins that perform actual job tasks in Dkron. They implement different execution strategies and allow Dkron to interact with various systems and services.

Overview

Executors define how jobs are executed on target nodes. When a job is scheduled to run, Dkron uses the specified executor to perform the actual work. Each executor has its own configuration options and capabilities.

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If you only plan to use the built-in executors, http and shell you can use the Dkron Light edition that only includes a single binary as the plugins are built-in.

Built-in Executors

Dkron includes the following built-in executors:

Executor	Description	Use Case
Shell	Executes shell commands on target nodes	Running scripts, system commands
HTTP	Makes HTTP requests to specified endpoints	API integrations, web hooks

Extended Executors (Open Source)

These executors are available as separate plugins in the open source version:

Executor	Description	Use Case
Kafka	Produces messages to Kafka topics	Event-driven architectures, data pipelines
NATS	Publishes messages to NATS servers	Microservices communication, event publishing
RabbitMQ	Sends messages to RabbitMQ exchanges	Message queuing, work distribution
gRPC	Makes calls to gRPC services	Microservices integration, efficient RPC
Google Pub/Sub	Publishes messages to Google Pub/Sub topics	Cloud-native event publishing

Pro Executors

Dkron Pro includes additional commercially supported executors:

Executor	Description	Use Case
Docker	Runs containers and commands within containers	Isolated execution environments
AWS ECS	Runs tasks on Amazon ECS clusters	Serverless job execution in AWS

Executor Architecture

Executors follow a plugin architecture in Dkron:

1. The Dkron server schedules a job and assigns it to a node
2. The node loads the specified executor plugin
3. The executor performs its action on the target system
4. Results are returned to Dkron for processing

Common Executor Configuration Patterns

Most executors share some common configuration concepts:

1. Timeouts: Limit how long a job can run before being terminated
2. Environment Variables: Pass context to the execution environment
3. Credentials: Securely provide authentication information
4. Retry Logic: Define behavior when execution fails

Executor Selection Guide

When choosing an executor for your job, consider:

1. Target System: What system or service needs to be interacted with?
2. Isolation Needs: Does the job need to run in an isolated environment?
3. Resource Requirements: How much CPU/memory is needed?
4. Security Considerations: What permissions or credentials are required?

Custom Executors

Dkron supports custom executors through its plugin system. You can develop your own executors to meet specific requirements not covered by existing plugins.

To develop a custom executor:

1. Implement the Executor interface from the Dkron plugin package
2. Follow the Go plugin system requirements
3. Build and deploy your executor to the Dkron plugins directory

See the plugin development guide for more details.

Best Practices

1. Use the Simplest Executor: Choose the simplest executor that meets your requirements
2. Set Appropriate Timeouts: Always configure timeouts to prevent runaway jobs
3. Validate Output: Use processors to validate and act on executor output
4. Monitor Resource Usage: Pay attention to the resource consumption of jobs
5. Security First: Follow the principle of least privilege when configuring executor permissions