safetynet v1.0.0

Safety Net

This module wraps your Google Cloud Function that subscribes to cloud pubsub topics to automatically decode data payloads and republish messages when your function fails

'use strict';

const SafetyNet = require('safetynet');
// SafetyNet.authenticate({ projectId: 'your-project', keyFilename: '/path/to/keyfile.json' });
// if, for some reason, you need to pass credentials this is how


// all configurable options listed below with their defaults
SafetyNet.configure({
  retries: 3,                    // how many times to allow a message to be retried
  attemptsKey: '_attempts',      // the key on the message to store the retry count
  failBehavior: 'error',         // what to do when the retry limit has been reached, can be 'error' or 'republish'
  errorTopic: 'safetynet-errors' // the topic to publish to when 'failBehavior' is set to 'republish'
});

exports.myFunction = SafetyNet.catch((data, event) => {

  return someAsyncMethod(data); // anything that returns a promise
});

The message object will flow like so:

                                                          
                  ┌──────────────────┐                    
                  │                  │                    
                  │ Original PubSub  │                    
                  │      Topic       │◀──────────────────┐
                  │                  │                   │
                  └──────────────────┘                   │
                            │                            │
                            ▼                            │
                    ┌───────────────┐                    │
                    │               │                    │
                    │ Your Function │                    │
                    │               │                    │
                    └───────────────┘                    │
                ┌───────┐   │   ┌───────┐                │
           ┌────┤Success├───┴───┤Failure├─┐              │
           │    └───────┘       └───────┘ ▼              │
           ▼                     ┌────────────────┐      │
       ┌──────┐                  │   Increment    │      │
       │ Exit │                  │ attempt count  │      │
       └──────┘                  └────────────────┘      │
           ▲                              │              │
           └──────┐              ┌────────┴───────┐      │
                  │              ▼                ▼      │
           ┌────────────┐    ┌───────┐        ┌───────┐  │
           │failBehavior│    │ over  │        │ under │  │
           │  = error   │◀─┬─│ retry │        │ retry │──┘
           └────────────┘  │ │ limit │        │ limit │   
                           │ └───────┘        └───────┘   
                           │                              
            ┌────────────┐ │                              
            │failBehavior│ │                              
            │= republish │◀┘                              
            └────────────┘                                
                   │                                      
                   ▼                                      
           ┌───────────────┐                              
           │               │                              
           │    PubSub     │                              
           │  errorTopic   │                              
           │               │                              
           └───────────────┘