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Background Processing App on Cloud Run Tutorial

Contains the code for using Cloud Firestore, Cloud Translate, and Cloud Pub/Sub.

This is part of the getting started experience.

Running Locally

To run your project locally:

  • Choose a Pub/Sub Topic Name and generate a Pub/Sub Verification Token using uuidgen or an online UUID generator such as uuidgenerator.net.

    export PUBSUB_TOPIC=<your-topic-name>
export PUBSUB_VERIFICATION_TOKEN=<your-verification-token>
export FIRESTORE_CLOUD_PROJECT=<your-project-id>

  • Create a Pub/Sub topic:

    gcloud pubsub topics create $PUBSUB_TOPIC

  • Run with the Jetty Maven plugin:

    mvn jetty:run-exploded

Note: If you run into an error about Invalid Credentials, you may have to run:

gcloud auth application-default login
  • Navigate to http://localhost:8080/
  • Click + Request Translation, and fill out the form using a phrase, a source language code ("en" for English) and a target language code (e.g. "es" for Spanish).
  • Click Submit. This will submit the request to your Pub/Sub topic and redirect you back to the list page.

You will see that nothing has changed. This because there is no subscription on that Pub/Sub topic yet. Since you can't set up a Pub/Sub push subscription to post requests to localhost, you can instead send a manual request with curl (from a second terminal, in the getting-started-java/background directory):

curl -H "Content-Type: application/json" -i --data @sample_message.json \
   "localhost:8080/pubsub/push?token=$PUBSUB_VERIFICATION_TOKEN"

Refresh http://localhost:8080 now and you will see a translated entry in the list.

Deploying to Cloud Run

To build your image:

  • Update the parameters in pom.xml:

    • Replace MY_PROJECT with your project ID.

  • Build and deploy to your GCR with the Jib Maven plugin.

    mvn clean package jib:build

  • Deploy the app to Cloud Run:

    gcloud beta run deploy background --image gcr.io/<MY_PROJECT>/background \
      --platform managed --region us-central1 --memory 512M \
      --update-env-vars PUBSUB_TOPIC=$PUBSUB_TOPIC,PUBSUB_VERIFICATION_TOKEN=$PUBSUB_VERIFICATION_TOKEN

    Where <MY_PROJECT> is the name of the project you created.

  • Create a Pub/Sub Subscription that will send requests to the Cloud Run endpoint created with the previous command:

    gcloud pubsub subscriptions create <your-subscription-name> \
      --topic $PUBSUB_TOPIC --push-endpoint \
      <CLOUD_RUN_ENDPOINT>/translate?token=$PUBSUB_VERIFICATION_TOKEN \
      --ack-deadline 30

    This command will output a link to visit the page, hereafter called <CLOUD_RUN_ENDPOINT>.

  • Now fill out the + Request Translation form again, this time at <CLOUD_RUN_ENDPOINT>. When you click Submit it will redirect you back to /translate.

    • The new request will take a moment to show, so refresh after a minute or two.

Architecture

The flow of translation requests fits together as such:

  • When the + Request Translation form is submitted, it posts a message to the Pub/Sub topic you created with the Text as (encoded) data, and the source/target language codes as attributes.
  • The Subscription you created receives this data and pushes it to the Cloud Run endpoint (with a POST request to /translate).
  • The /translate endpoint processes POST requests (that include the correct PUBSUB_VERIFICATION_TOKEN) by performing the Translate request and saving the result in Firestore.
  • When you visit the Cloud Run endpoint, it reads the past 10 requests from Firestore and shows them in a table at the / or /translate endpoints.