ReefGuideWorkerTemplate.jl

A Julia-based worker template for the open-AIMS/reefguide distributed job processing system. This template provides a foundation for implementing custom job handlers that can process tasks from the ReefGuide job queue.

Where does it fit in?

ReefGuideWorkerTemplate.jl is a template worker node in the reefguide system.

ReefGuide deploys ReefGuideWorker.jl and ADRIAReefGuideWorker.jl as Docker containers on ECS to consume jobs generated by users in the frontend. They each use their respective Julia library, and fork the template repository. Shown below.

graph TD
    RG[ReefGuide] -->|deploys| RGW[ReefGuideWorker.jl<br/>Docker Container]
    RG -->|deploys| ARGW[ADRIAReefGuideWorker.jl<br/>Docker Container]

    RGW -->|uses| RGLib[ReefGuide.jl<br/>Julia Library]
    ARGW -->|uses| ADRIALib[ADRIA.jl<br/>Julia Library]

    RGW -->|forks| RGWT[ReefGuideWorkerTemplate.jl<br/> Template]
    ARGW -->|forks| RGWT

    style RG fill:#e1f5fe
    style RGW fill:#f3e5f5
    style ARGW fill:#f3e5f5
    style RGLib fill:#e8f5e8
    style ADRIALib fill:#e8f5e8
    style RGWT fill:#fff3e0

Loading

Related repos include

• ReefGuide - the main ReefGuide repository
• ReefGuideWorker.jl - Julia Job Worker to run ReefGuide algorithms
• ReefGuide.jl - ReefGuide Julia library code
• ADRIA.jl - The ADRIA model Julia library code, used by ADRIAReefGuideWorker.jl
• ADRIAReefGuideWorker.jl - Julia Job Worker to run ADRIA algorithms for ReefGuide

Context

This worker template integrates with the ReefGuide ecosystem, connecting to the ReefGuide web API to receive and process distributed computing tasks. The API_ENDPOINT environment variable should point to your ReefGuide web API instance.

For local development: First spin up the local ReefGuide stack by following the setup instructions in the ReefGuide README. This will provide the necessary API endpoint and supporting services (database, S3 storage, etc.) that the worker connects to.

Quick Start

Prerequisites

• Install Julia 1.11.x using juliaup:

  curl -fsSL https://install.julialang.org | sh
  juliaup add 1.11
  juliaup default 1.11

Setup and Development

Local Development

1. Copy the environment template:

   cp .env.local .env

2. Navigate to the sandbox/ directory
3. Initialize the project:

   ./init.sh

4. Start the development environment:

   ./start.sh

Docker Development

1. Copy the environment template:

   cp .env.local .env

2. Build the Docker image:

   docker build . -t worker

3. Run the container:

   docker run --env-file .env worker

How It Works

Core Architecture

The worker operates on a polling-based architecture:

1. Polling: Continuously polls the ReefGuide API for available jobs
2. Job Assignment: Claims jobs that match its configured job types
3. Processing: Executes the appropriate handler for each job type
4. Completion: Reports results back to the API
5. Idle Timeout: Automatically shuts down after a configurable period of inactivity

Job Handlers

Job processing is handled through a type-safe registry system:

• Job Types: Defined as enums in handlers.jl (e.g., TEST)
• Input/Output Types: Strongly typed payloads for each job type
• Handlers: Implement the AbstractJobHandler interface to process specific job types

Example: TEST Job Handler

The template includes a complete example:

# Input payload structure
struct TestInput <: AbstractJobInput
    id::Int64
end

# Output payload structure
struct TestOutput <: AbstractJobOutput
end

# Handler implementation
struct TestHandler <: AbstractJobHandler end

function handle_job(::TestHandler, input::TestInput, context::JobContext)::TestOutput
    @debug "Processing test job with id: $(input.id)"
    sleep(10)  # Simulate work
    return TestOutput()
end

Configuration

Configure the worker through environment variables (see .env.local for examples):

• API_ENDPOINT: ReefGuide API base URL
• JOB_TYPES: Comma-separated list of job types to handle
• WORKER_USERNAME/PASSWORD: Authentication credentials
• AWS_REGION: AWS region for S3 storage
• S3_ENDPOINT: Optional S3-compatible endpoint (for local development)

Storage Integration

Workers can read from and write to S3-compatible storage:

• Each job assignment includes a unique storage_uri for outputs
• Use the provided JobContext to access storage configuration
• Support for both AWS S3 and local MinIO development environments

Adding New Job Types

1. Define the job type enum in handlers.jl
2. Create input/output payload structs
3. Implement a handler struct and handle_job method
4. Register the handler in the __init__() function

Development vs Production

• Development: Uses local MinIO for S3 storage and local API endpoint
• Production: Runs in AWS ECS Fargate with proper AWS S3 integration
• Docker: Includes multi-stage Dockerfile for containerized deployment

Threading

The worker is designed to be single-threaded per job but can utilize Julia's threading for computationally intensive tasks within job handlers.