Cloud Functions

Cloud Functions supports the running of single-purpose functions that behave in isolation. The default time out is 1 minute and the max possible is 9 minutes.

Cloud Functions is suited for logic tests and small, defined tasks. Have a photosharing tool? Cloud Functions can manage the code to check a user is uploading an image file and pass the T/F answer back to the app as part of the logic before the upload is accepted.

In this example, an Event, an upload to Cloud Storage, Triggers the Function to create an Event and send a message back to the app system, say via Cloud Pub/Sub’s messaging service.

The integration options are myriad:

  • Trigger an Event using HTTP verbs (the normal API POST, GET, PUT, DELETE) and OPTIONS
  • Forward Stackdriver logs to Pub/Sub and trigger a response from there
  • Upload, Delete, Update of metadata, and Archive in Cloud Storage
  • Firebase database Events

Runtime Environments

Currently include:

  • Python 3
  • Node.js 6 & 8

The supported languages (at time of writing) include:

  • Python
  • Go
  • JS / Node.js

Using Cloud Functions on the GCP

Console

GCP> Compute> Cloud Functions

Requirements:

  1. Cloud Functions Engine API
  2. Your SDK / Cloud Shell may need its environment updated to support your runtime environment

Settings include:

  • Function Name
    for use on GCP, different to the name of the function to be called!
  • Name
    of the function to execute
  • Memory allocation
  • Trigger
    • HTTP / Cloud Pub/Sub / Cloud Storage
  • Event type
  • Location of code
  • Runtime environment
  • Source Code

Cloud Functions from the CLI

The command to deploy is:

gcloud functions deploy {function-name}

The command accepts 3 parameters:

  • runtime
    • i.e. Python 3.7 or the Node version
  • trigger-resource
    • defines the bucket name if a Cloud Bucket is associated with this task
  • trigger-event
    • defines the event type

So the following function:

gcloud functions deploy {function-name}
        --runtime python37
        --trigger-resource {bucket-name}
        --trigger-event google.storage.object.delete

is triggered by a delete occuring on a named bucket.

As Cloud Function is simply yet another GCP API, it merrily provides a payload upon successful completion. This is presented as a log message.

Integration with Cloud Pub/Sub

If the trigger is to be Cloud Pub/Sub, this can be selected from the console (or coded in the CLI). You will then be prompted to identify the name of the Pub/Sub topic, if this name does not exist it will be automatically created.