Temporary Files in Genezio Functions

This tutorial will walk you through reading and writing temporary files from Genezio Functions. We'll cover how bundling operates and how Genezio includes additional files for runtime use in your functions.

Bundling Genezio Functions

Your application is by default bundled by Genezio to include all necessary user code and dependencies needed for runtime.

You can ignore files or directories from the bundling process by adding them to the .genezioignore file in the root of your project. Learn more about the .genezioignore file here.

Examples of reading files

Use process.cwd() to determine the current directory of the Genezio Function.

./server/index.mjs

import fs from 'fs';
import path from 'path';

export const handler = async () => {
  const filePath = path.join(process.cwd(), 'test.md');

  const data = fs.readFileSync(filePath, 'utf8');
  console.log("The file contents are:", data);

  return {
    statusCode: 200,
    body: data,
  };
};

To deploy this function to Genezio, you have to configure the genezio.yaml file. Learn more about the configuration file here.

Examples of writing files

Use process.cwd() to determine the current directory of the Genezio Function.

./server/index.mjs

import fs from 'fs';
import path from 'path';

export const handler = async () => {
  const filePath = path.join(process.cwd(), 'test.md');

  fs.writeFileSync(filePath, '# Hello, World!');

  return {
    statusCode: 200,
    body: 'File written successfully',
  };
};

To deploy this function to Genezio, you have to configure the genezio.yaml file. Learn more about the configuration file here.

Note: When using Function-as-a-Service (FaaS) platforms like Genezio, file system within these environments is ephemeral. This means that any files written to or modified within the function's execution environment will not persist after the function is killed. To use local files, you typically bundle them with your function during deployment, ensuring they are available at runtime. However, since the file system is temporary, any changes made to these files won't be saved after the function completes its execution. For persistent data storage, you'll need to use external storage solutions such a KV store or a database.

Learn how to connect a Postgres or a Redis database to your Genezio function in the Tutorials section.