gcp-emulator

GCP Emulator

Roughly emulate Google Cloud Platform services for development.

Emulators

• Cloud Functions cloud-functions
• Cloud Storage cloud-storage
• Cloud Tasks cloud-tasks

Getting Started

Install the package.

yarn add -D gcp-emulator

Use as a CLI.

gcp-emulator emulate --emulators cloud-functions --cloud-functions-filepath ./function.js

Use as a Library.

import { EmulatorCloudFunctions } from "gcp-emulators";

const emulatorCloudFunctions = new EmulatorCloudFunctions({
  filepath: "./function.js",
  server: {
    port: 9010,
    hostname: "localhost",
    ssl: ...,
  },
});

Logging

The logger supports the following types of logs *, info, warn, error.

You can configure which types of logs are output by setting the LOGGER environment variable or setting the UtilityLogger.level property.

Proxy

You can configure a proxy server for all http based emulators to use.

You can also configure the proxy to use ngrok.

CLI Usage

Options

Argument	Description	Value
--config	javascript or json config	.gcprc.js

emulate command

gcp-emulator emulate [options]

Options

Argument	Description	Value
--emulators	emulators to use	cloud-functions,cloud-storage,cloud-tasks
--proxy	proxy emulators	true
--proxy-port	proxy server port	9000
--proxy-ngrok	proxy with ngrok	true
--proxy-ngrok-authtoken	proxy ngrok authtoken	xxx
--proxy-ngrok-subdomain	proxy ngrok subdomain	gcp-emulator
--ssl-key-filepath	global server ssl key path	./key.pem
--ssl-cert-filepath	global server ssl cert path	./cert.pem
--cloud-functions-port	cloud-functions emulator server port	9010
--cloud-functions-filepath	cloud-functions emulator source path	./function.js
--cloud-functions-ssl-key-filepath	cloud-functions emulator server ssl key path	./key.pem
--cloud-functions-ssl-cert-filepath	cloud-functions emulator server ssl cert path	./cert.pem
--cloud-storage-port	cloud-storage emulator server port	9020
--cloud-storage-filepath	cloud-storage emulator source path	./public
--cloud-storage-ssl-key-filepath	cloud-storage emulator server ssl key path	./key.pem
--cloud-storage-ssl-cert-filepath	cloud-storage emulator server ssl cert path	./cert.pem

CLI Config

The file provided to the --config argument should return the following Javascript object structure when required in Node.

{
  [commandName]: {
    [camelCaseArgument]: value;
  }
}

Caveats & Limitations

The Cloud Functions emulator clears the require.cache before executing the function, this improves the development experience but may cause issues of it's own in certain situations.

The Cloud Storage emulator is more-or-less a simple static server.

The Cloud Tasks emulator uses sinon to stub the @google-cloud/tasks package so it is required for the emulator to operate.

Depending on your usage a built-in 404 page will be sent to requests that cannot be resolved to an emulator, or where an emulator cannot resolve the request, this does not align with any particular Google Cloud Platform service but seems more useful than not having it.