CouchEye

The CouchEye tool can be used to monitor changes in one or more CouchDb databases and send notifications to topics in the Amazon Simple Notification Service (SNS). Multiple databases can be monitored by one running CouchEye instance and changes can be routed to multiple topics, which may even be in different regions or require diferrent credentials.

To use CouchEye, simple install is using npm:

npm install --save coucheye

Below you'll find an example configuration using CoffeeScript syntax.

Configuration options

Key	Description
redis	Object as returned by createClient in the redis package
redisUrl	URL of the Redis server; required unless redis option is given
redisPrefix	Sequence numbers for a feed are stored under #{redisPrefix}#{feedName}
feeds	A set of CouchDb feeds
feeds.{name}.*	Properties as accepted by the follow package
endpoints	A set of Amazon AWS endpoints, including credentials
endpoints.{name}.*	Properties as accepted by the aws-sdk package
topics	A set of SNS topics to which changes can be published
topics.{name}.arn	ARN of an SNS topic
pipes	A set of pipes that connect feeds, endpoints and topics
pipes.{name}.feed	Name of the feed to draw change from
pipes.{name}.endpoint	Name of the endpoint to send notifications to
pipes.{name}.topic	Name of the topic to send notifications to
pipes.{name}.transformChange	Function to transform a change object
pipes.{name}.transformDoc	Function to transform a change document; depends on feeds.<name>.include_docs options

The pipes.<name>.transformChange and pipes.<name>.transformDoc options are not required, but are mutually exclusive. When either of those is used, the return value is used as content for the notification. If null or undefined is returned, not notification is published.

Example configuration

coucheye = (require 'coucheye')
    redisUrl: 'redis://username:[e-mail]:9356/'
    redisPrefix: 'coucheye.'
    feeds:
        examples:
            db: 'https://username:[e-mail]/examples'
            include_docs: true
        extensions:
            db: 'https://username:[e-mail]/extensions'
            include_docs: true
    endpoints:
        sns:
            accessKeyId: 'akid'
            secretAccessKey: 'secret'
            region: 'eu-west-1'
    topics:
        exampleUpdated: 'arn:aws:sns:eu-west-1:123456789012:ExampleUpdated'
        exampleCompleted: 'arn:aws:sns:eu-west-1:123456789012:ExampleCompleted'
        extensionCreated: 'arn:aws:sns:eu-west-1:123456789012:ExtensionCreated'
        extensionApproved: 'arn:aws:sns:eu-west-1:123456789012:ExtensionApproved'
    pipes:
        exampleUpdated:
            feed: 'examples'
            endpoint: 'sns'
            topic: 'exampleUpdated'
            transformChange: (change) ->
                # Ignore deletions
                return null if change.deleted
                exampleId: change.id
        exampleCompleted:
            feed: 'examples'
            endpoint: 'sns'
            topic: 'exampleCompleted'
            transformDocument: (doc) ->
                # Only notify for completed example
                return null unless doc.status is 'COMPLETED'
                exampleId: doc._id
        extentionCreated:
            feed: 'extensions'
            endpoint: 'sns'
            topic: 'extensionCreated'
            transformDocument: (doc) ->
                # First revision means document has just been created
                return null unless doc._rev.match(/^1-/)?
                extensionId: doc._id
        extensionApproved:
            feed: 'extensions'
            endpoint: 'sns'
            topic: 'extensionApproved'
            transformDocument: (doc) ->
                # Require an approval
                return null unless doc.approval?
                # But not an error
                return null if doc.error?
                extensionId: doc._id
 
coucheye.on 'error', (err) ->
    console.err err
    process.exit 1
 
coucheye.start()