The cost for each request has a static value of 100. ComfyUI does not handle concurrent workloads and there is no current provision to load multiple instances of ComfyUI per worker node.

Requirements

This worker requires both ComfyUI and ComfyUI API Wrapper.

A docker image is provided but you may use any if the above requirements are met.

Endpoint

The worker provides a single endpoint:

/generate/sync: Processes ComfyUI workflows using either predefined modifiers or custom workflow JSON

Request Format

The worker accepts requests in the following format. Choose either modifier mode OR custom workflow mode:

Modifier Mode:

{
  "input": {
    "request_id": "uuid-string",    // optional - UUID generated if not provided
    "modifier": "RawWorkflow",
    "modifications": {
      "prompt": "a beautiful landscape",
      "width": 1024,
      "height": 1024,
      "steps": 20,
      "seed": 123456789
    },
    "s3": { ... },       // optional
    "webhook": { ... }   // optional
  }
}

Custom Workflow Mode:

{
  "input": {
    "request_id": "uuid-string",    // optional - UUID generated if not provided
    "workflow_json": {
      // Complete ComfyUI workflow JSON
    },
    "s3": { ... },       // optional
    "webhook": { ... }   // optional
  }
}

Request Fields

Required Fields

input: Contains the main workflow data
input.request_id: Unique identifier for the request

Workflow Mode (Choose One)

You must provide either modifier OR workflow_json, but not both:

Option 1: Modifier Mode

input.modifier: Name of the predefined workflow modifier (e.g., "Text2Image")
input.modifications: Parameters to pass to the modifier

Option 2: Custom Workflow Mode

input.workflow_json: Complete ComfyUI workflow JSON

Optional Fields

input.s3: S3 configuration for file storage
input.webhook: Webhook configuration for notifications

These configurations can be provided in the request JSON or via environment variables. Request-level configuration takes precedence over environment variables.

S3 Configuration

Via Request JSON:

"s3": {
  "access_key_id": "your-s3-access-key",
  "secret_access_key": "your-s3-secret-access-key", 
  "endpoint_url": "https://my-endpoint.backblaze.com",
  "bucket_name": "your-bucket",
  "region": "us-east-1"
}

Via Environment Variables:

S3_ACCESS_KEY_ID=your-key
S3_SECRET_ACCESS_KEY=your-secret
S3_BUCKET_NAME=your-bucket
S3_ENDPOINT_URL=https://s3.amazonaws.com
S3_REGION=us-east-1

Webhook Configuration

Via Request JSON:

"webhook": {
  "url": "your-webhook-url",
  "extra_params": {
    "custom_field": "value"
  }
}

Via Environment Variables:

WEBHOOK_URL=https://your-webhook.com  # Default webhook URL
WEBHOOK_TIMEOUT=30                   # Webhook timeout in seconds

Examples

Basic Text-to-Image (Modifier Mode)

{
  "input": {
    "modifier": "Text2Image",
    "modifications": {
      "prompt": "a cat sitting on a windowsill",
      "width": 512,
      "height": 512,
      "steps": 20,
      "seed": 42
    }
  }
}

Custom Workflow Mode

{
  "input": {
    "request_id": "67890",    // optional - using custom ID for tracking
    "workflow_json": {
      "3": {
        "inputs": {
          "seed": 42,
          "steps": 20,
          "cfg": 8,
          "sampler_name": "euler",
          "scheduler": "normal",
          "denoise": 1,
          "model": ["4", 0],
          "positive": ["6", 0],
          "negative": ["7", 0],
          "latent_image": ["5", 0]
        },
        "class_type": "KSampler"
      }
    }
  }
}

Client Libraries

See the client example for implementation details on how to integrate with the ComfyUI worker.

See Vast's serverless documentation for more details on how to use ComfyUI with autoscaler.