Processor Development

Processors are the transformation engines that convert template files into generated output. The default processor uses Eta templating, but you can create custom processors for any transformation needs.

What is a Processor?

A processor is a Docker container that:

Receives files from the template's blob image
Transforms content based on configuration
Outputs files to the write directory

Processors are stateless file transformers - they receive input files and produce output files without side effects.

Processor Architecture

Components

Component	Purpose	Examples
Entry Point	Processor logic	`StartProcessorWithLambda`
CyanFileHelper	File operations	`resolveAll()`, `read()`, `copy()`
CyanProcessorInput	Input from template	Config, globs, directories
ProcessorOutput	Return value	Output directory path

Why Create a Custom Processor?

Different Templating Engines

The default processor uses Eta with var__name__ syntax. You might need:

Engine	Use Case
Jinja	Python-style templates
Go templates	Helm/Kubernetes manifests
Mustache	Logic-less templates
Handlebars	Rich template features

Custom Logic

Processors enable custom processing that goes beyond simple variable substitution:

Code generation (GraphQL, Protobuf, OpenAPI)
AST transformations
Binary file processing
Multi-step pipelines

Processors should be pure functions - same input always produces same output. This ensures reproducible project generation.

Learning Path

Tutorials

Build your first processor step by step

How-To Guides

Task-oriented guides for common scenarios

Reference

Technical documentation for the SDK

Explanation

Deep dives into processor concepts

Quick Example

Here's a minimal processor that uppercases all file content:

index.ts

import { StartProcessorWithLambda } from '@atomicloud/cyan-sdk';

StartProcessorWithLambda(async (input, fileHelper) => {
  const files = fileHelper.resolveAll();

  files.forEach(file => {
    file.content = file.content.toUpperCase();
    file.writeFile();
  });

  return { directory: input.writeDir };
});

main.py

from cyanprintsdk.processor import start_processor_with_fn
from cyanprintsdk.protocol import ProcessorInput, ProcessorOutput

async def processor(input: ProcessorInput, file_helper) -> ProcessorOutput:
    files = file_helper.resolve_all()

    for file in files:
        file.content = file.content.upper()
        file.write_file()

    return ProcessorOutput(directory=input.write_dir)

processor_main = start_processor_with_fn(processor)

Processor.cs

using CyanPrintSDK;

public static class Processor
{
    [ProcessorMain]
    public static async Task<ProcessorOutput> Run(ProcessorInput input, CyanFileHelper fileHelper)
    {
        var files = fileHelper.ResolveAll();

        foreach (var file in files)
        {
            file.Content = file.Content.ToUpper();
            file.WriteFile();
        }

        return new ProcessorOutput { Directory = input.WriteDir };
    }
}

Processor Development

Processor Development

What is a Processor?

Processor Architecture

Components

Why Create a Custom Processor?

Different Templating Engines

Custom Logic

Learning Path

Tutorials

How-To Guides

Reference

Explanation

Quick Example

Next Steps

On this page