Hello, World!

The goal of this tutorial is to build a simple ByteNite app that outputs the string "Hello, World!" to a file. Use this tutorial if you're new to ByteNite and want to have a quick sense of the workflow.

Duration	Difficulty	Prerequisites
~15 min	Very Easy	Onboarding ByteNite Dev CLI

---

1

Download sample app

Run the app new command in your terminal to create an app directory locally named "hello-world":

bytenite app new hello-world

Check that a new directory named "hello-world" was indeed created at your base path:

ls

2

Write the main script

Locate your pre-generated Python entry point (./hello-world/app/main.py) and add the code to the file.

We'll make the app perform a few simple steps:

• Read a string from the input text file (chunk).

• Convert the string to a case matching the input parameter 'case'.

• Write the result to a text file in the task results directory.

main.py

if __name__ == '__main__':
    print("Python task started")
    result_path = os.path.join(task_results_dir, 'processed_chunk.txt')
    try:
         # 1. Reading Inputs
    
        # Expect a text file to be passed by the partitioner
        with open(chunk_path, 'r', encoding="utf-8") as infile:
            my_string = infile.read()

        # 2. Handling Parameters
        
        # Expect the job parameters to have a key named 'case', and the options to be "upper", "lower", and "title"
        case = app_params['case']

        # 3. Developing the Core Functionality
        
        # Process the string based on the case parameter
        if case == "upper":
            my_string = my_string.upper()
        elif case == "lower":
            my_string = my_string.lower()
        elif case == "title":
            my_string = my_string.title()
        else:
            my_string = my_string
        
        # 4. Saving Outputs

        # Save the string directly into a text file to the default task results directory
        with open(os.path.join(task_results_dir, "hello_world_processed.txt"), 'w', encoding="utf-8") as outfile:
            outfile.write(my_string)

    except Exception as e:
        print("Python exception: ", e)
        raise e

3

Check your manifest and template files

The manifest and template files are automatically generated and located in your hello-world directory. Ensure they contain the correct configurations as shown below.

Note: We're using passthrough partitioning and assembling engines in this template, so there's no need to configure these components.

manifest.json

{
  "name": "hello-world",
  "version": "0.1",
  "platform": "docker",
  "description": "An app named hello-world",
  "entrypoint": "main.py",
  "platform_config": {
    "container": "python:latest"
  },
  "device_requirements": {
    "min_cpu": 2,
    "min_memory": 2
  }
}

template.json

{
  "id": "hello-world-template",
  "description": "A template for hello-world",
  "app": "hello-world",
  "partitioner": "passthrough",
  "assembler": "passthrough"
}

4

Submit and activate your app

Upload the content of your app:

bytenite app push hello-world

Activate your app to make it accept jobs:

bytenite app activate hello-world

Now, check your app's details and status by running the command:

bytenite app get hello-world

Finally, ensure that your template was correctly uploaded—you will need that for running jobs.

bytenite template get hello-world-template

5

Launch a job with 'hello-world-template'

Let's launch a job with your new hello-world-template and test your app.

Send a POST request to the Job Create endpoint, including the following fields in the request body:

Key	Value
templateId	hello-world-template
dataSource	{ "dataSourceDescriptor": "url", "params": { "@type": "type.googleapis.com/bytenite.data_source.HttpDataSource", "url": "https://storage.googleapis.com/video-test-public/hello-world-I.txt" } }
dataDestination	{ "dataSourceDescriptor": "bucket" }
params	{ "app": { "case": "upper" } }

Then, launch your job and check the results.

Here's a Postman collection that you can use to run your Hello World job:

Tutorial: Hello, World! | ByteNite API DemosPostman