nodejs

Nebulous serverless Cloud Translation API app

Node.js version

The Node.js version of this app and its deployments are simpler than the Python equivalent, primarily due to the differences between Python 2 and 3, and also because Node.js is not an App Engine legacy runtime. As a result, there is a single Node.js codelab for deploying this app while there are seven for Python.

Deployments and their files

File	Description
index.js	main application file
templates/index.html	application HTML template
package.json	3rd-party package requirements file
app.yaml	App Engine configuration file (only for App Engine deployments)
test/test_neb.js	unit tests (mocha & supertest)
.gcloudignore	files to exclude deploying to the cloud (administrative)
README.md	this file (administrative)

Below are the required settings and instructions for all (documented) deployments; administrative files are not discussed. The app.yaml file is only used for specific deployments and can be deleted for the others.

NOTE: Serverless deployments (as configured here) use default service accounts which provide a broad set of permissions to assist you in getting a working prototype. When preparing to launch to production, the Google Cloud team recommends the best practice of "least privileges," and instead use user-managed service accounts with the minimal set of permissions allowing your app to function properly.

Local Express server (Node 10, 17)

TL;DR: application files (index.js & package.json). Instructions:

1. Run npm install (to install packages locally)
2. Run gcloud auth application-default login to set your credentials
3. Run npm start to run locally

App Engine (Node 10, 12, 14, 16)

TL;DR: application files plus app.yaml. You may (first) edit app.yaml to specify the desired Node version (default: Node 16). Instruction(s):

1. Run gcloud app deploy to deploy to App Engine
   • You'll be prompted for the REGION if deploying to App Engine the first time.
   • App Engine apps are tied to one region, so it can't be changed once it's set, meaning you won't be prompted thereafter.

Cloud Functions (Node 10, 12, 14, 16)

TL;DR: Uses only the application files. Instruction(s):

1. Run gcloud functions deploy translate --runtime nodejs16 --entry-point app --trigger-http --allow-unauthenticated to deploy to Cloud Functions (or Node 10, 12, 14)
   • You'll be prompted for the REGION if deploying a Cloud Function the first time.
   • Cloud Functions can be deployed to different regions within a project, but once the region has been set for a function, it cannot be changed.

The command creates & deploys a new HTTP-triggered Cloud Function named translate. Cloud Functions is directed to call the application object, app, via --entry-point. During execution translate() is called by app. In the Python version, --entry-point is unnecessary because translate() is the application entry point.

Cloud Run (Node 10+ via Cloud Buildpacks)

TL;DR: Uses only the application files. Instruction(s):

1. Run gcloud run deploy translate --allow-unauthenticated --platform managed --source . to deploy to Cloud Run
   • You'll be prompted to provide a REGION unless you also add --region REGION on the cmd-line which will give you a full non-interactive deploy
   • A Dockerfile is optional, but if you wish to create one, place it in the top-level folder so the build system can access it. Also see the Python version's Dockerfile to get an idea of what a Node equivalent would be similar to.

References

These are relevant links only to the app in this folder (for all others, see the README one level up:

• Node.js App Engine quickstart
• Nodejs App Engine (standard environment) runtime
• Node.js Cloud Functions quickstart
• Node.js Cloud Run quickstart
• Express.js

Testing

Testing is driven by mocha which uses supertest for testing and eslint for linting, installing both in virtual environments along with application dependencies, express, nunjucks, and @google-cloud/translate. To run the unit tests (testing GET and POST requests), run npm install followed by npm test).

Expected output

$ npm test

> [email protected] test
> mocha test/test_neb.js

Listening on port 8080


  Our application
    ✔ GET / should result in HTML w/"translate" in the body
    ✔ POST / should have translated "hello world" correctly (140ms)
DONE


  2 passing (170ms)

Troubleshooting

When running the test, there's a situation which resulting in the test hanging like this:

$ npm test

> [email protected] test
> mocha test/test_neb.js

Listening on port 8080


  Our application
    ✔ GET / should result in HTML w/"translate" in the body
    1) POST / should have translated "hello world" correctly
DONE


  1 passing (2s)
  1 failing

  1) Our application
       POST / should have translated "hello world" correctly:
     Error: Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (/tmp/cloud-nebulous-serverless/cloud/nodejs/test/test_neb.js)
      at listOnTimeout (node:internal/timers:557:17)
      at processTimers (node:internal/timers:500:7)

(hangs here)

If this happens to you, run gcloud auth application-default login to set your credentials and try again.