The echo-multi app

Several examples assume you have a Nextmv application called echo-multi. This is just a simple application created for demonstration purposes. It takes the input files and echoes them as output files.

Let's get set up with the echo-multi application. Before starting:

1. Sign up for a Nextmv account.
2. Get your API key. Go to Team > API Key.

Make sure that you have your API key set as an environment variable:

export NEXTMV_API_KEY="<YOUR-API-KEY>"

Now that you have a valid Nextmv account and API key, let's create the echo-multi Nextmv app (start in an empty directory).

1. Create a folder inputs/ and add some sample input files to it. For example, you can create two text files input.csv and input.txt with some sample content.

2. In a new directory, create a file called main.py with the code for the basic app that echoes the input.

   import glob
   
   import os
   import time
   
   import nextmv
   
   def main():
       options = nextmv.Options(
           nextmv.Option("input", str, "inputs/", "Path to input file.", False),
           nextmv.Option("output", str, "outputs/", "Path to output file.", False),
           nextmv.Option("duration", float, 1.0, "Runtime duration (in seconds).", False),
       )
   
       # Read and prepare the input data.
       input_data = read_input(options.input)
   
       # Log information about the input files.
       nextmv.log(f"Size of input files (count: {len(input_data)}):")
       for file_path, content in input_data.items():
           nextmv.log(f"  {file_path}: {len(content)} bytes")
   
       # Sleep for the specified duration.
       nextmv.log(f"Sleeping for {options.duration} seconds...")
       time.sleep(options.duration)
       nextmv.log("Woke up from sleep.")
   
       # Write the output.
       write_output(options.output, input_data)
   
   def read_input(input_path: str) -> dict[str, bytes]:
       """Reads the input files to memory."""
       input_files = glob.glob(os.path.join(input_path, "**/*"), recursive=True)
       content = {}
       for file_path in input_files:
           if os.path.isfile(file_path):
               with open(file_path, "rb") as file:
                   nextmv.log(f"Reading file: {file_path}")
                   content[file_path] = file.read()
       return content
   
   def write_output(output_path: str, content: dict[str, bytes]) -> None:
       """Writes the given output files."""
       if not os.path.exists(output_path):
           os.makedirs(output_path)
   
       for file_path, data in content.items():
           output_file_path = os.path.join(output_path, os.path.basename(file_path))
           with open(output_file_path, "wb") as file:
               nextmv.log(f"Writing file: {output_file_path}")
               file.write(data)
   
   if __name__ == "__main__":
       main()
   

   Note that the application uses the nextmv library. This library is a dependency of nextpipe and should be installed automatically when you install nextpipe.

   You may run the app locally to test it:

   python main.py
   

3. Create a requirements.txt file with the following requirements for running the app:

   nextmv
   

4. Create an app.yaml file (the app manifest) with the following instructions:

   type: python
   runtime: ghcr.io/nextmv-io/runtime/python:3.11
   files:
       - main.py
   python:
       pip-requirements: requirements.txt
   

5. Push the application to your Nextmv account. Create a push.py script in the same directory with the following code:

   import os
   
   from nextmv import cloud
   
   client = cloud.Client(api_key=os.getenv("NEXTMV_API_KEY"))
   app = cloud.Application.new(client=client, name="echo-multi", id="echo-multi", description="Sample echo multi-file app.", exist_ok=True)
   app.push(verbose=True)
   

6. Execute the push.py script to push the app to your Nextmv account:

   $ python push.py
   💽 Starting build for Nextmv application.
   🐍 Bundling Python dependencies.
   📋 Copied files listed in "app.yaml" manifest.
   📦 Packaged application (588 files, 5.39 MiB).
   🌟 Pushing to application: "echo-multi".
   💥️ Successfully pushed to application: "echo-multi".
   {
   "app_id": "echo-multi",
   "endpoint": "https://api.cloud.nextmv.io",
   "instance_url": "v1/applications/echo-multi/runs?instance_id=devint"
   }
   

   Alternatively, you can use the Nextmv CLI to create and push the app:

   nextmv app create -a echo-multi -n echo-multi -d "Sample echo multi-file app."
   nextmv app push -a echo-multi
   

Now you are ready to run the examples.