Run Serverless Offline and Serverless Python Requirements together

PythonOfflineFix.js

#!/usr/bin/env node

"use strict";

const path = require("path");
const fs = require("fs");

/**
 * Custom Serverless plugin to fix an issue with Serverless Offline not resolving the requirements
 * path of the Serverless Python Requirements plugin.
 *
 * @see https://github.com/serverless/serverless-python-requirements/issues/311#issuecomment-976317821
 */
class PythonOfflineFix {
  constructor(serverless, options) {
    this.hooks = {
      "before:offline:start:init": () => this.setRequirementsPythonPath(serverless),
      "before:requirements:install:install": () => this.includeAllRequirements(serverless),
    };
  }

  async includeAllRequirements(serverless) {
    // Include all dependencies when running manual installation
    serverless.service.custom.pythonRequirements.noDeploy = [];
  }

  async setRequirementsPythonPath(serverless) {
    for (const func of Object.values(serverless.service.functions)) {
      const runtime = func.runtime || serverless.service.provider.runtime;
      if (runtime.match(/python/i) && func.handler) {
        if (func.module) {
          func.handler = `${func.module}/${func.handler}`;
          delete func.module;
        }
        if (!func.environment) {
          func.environment = {};
        }
        if (serverless.service.package?.individually) {
          func.environment.PYTHONPATH = fs.realpathSync(
            path.join(".serverless", path.dirname(func.handler), "requirements")
          );
        } else {
          func.environment.PYTHONPATH = fs.realpathSync(path.join(".serverless", "requirements"));
        }
      }
    }
  }
}

module.exports = PythonOfflineFix;