services/

README

Service packages structure

All service cloud function packages share a consistent structure

Two functions and one type

Initialize function

• Goal
  • Optimize cloud function performance by reducing the invocation latency
• Implementation
  • Is executed once per cloud function instance as a cold start.
  • Cache objects expensive to create, like clients
  • Retreive settings once, like environment variables
  • Cached objects and reteived settings are exposed in one global variable named global

Global type

• A struct to define a global variable carrying cached objects and retreived settings by Initialized function and used by EntryPoint function

EntryPoint function

• Goal
  • Execute operations to be performed each time the cloud function is invoked
• Implementation
  • Is executed on every event triggering the cloud function
  • Uses cached objects and retreived settings prepared by the Initialized function and carried by a global variable of type Global
  • Performs the task a given service is targetted to do that is described before the package key word

Automatic retrying

Automatic retrying is consistently implemented in RAM service packages as documented in Google Cloud Function best practice Retrying Background Functions

Impact on cloud functions Stackdriver logs:

• Errors entry in log only appears for transient errors.
  • As en error is reported the function is retried.
• Other errors and loged as information to avoid unwanted retries
  • To find errors in such cloud function logs you can use the following Stackdriver logging filter

resource.type="cloud_function"
textPayload:"REDO_ON_TRANSIENT"

The standard exponential backoff algorithm leads to have:

• 343 retries in one hour
• 157 retries during the first 100 seconds

Documentation

• ram GO packages are documented on line: https://godoc.org/github.com/BrunoReboul/ram