eevy

README

Description

eevy is a micro weight go based message broker.

Sources listen on http ports, AWS SQS queues etc for incoming events. Event listeners keep an eye out for events with specific names and invoke handlers when certain events are detected.

Handlers can invoke an AWS Lambda function, place the event data on an AWS SQS queue, call an http end point with OAuth2 authentication etc.

Getting started

Installing

From Source

Eevy is built using go so ensure that you have this properly installed first.

go get github.com/hevnly/eevy
go build github.com/hevnly/eevy

Using binary

Download the binary file from the github release page(currently built using Ubuntu system)

Configuration

A yaml file is used to configure the sources, handlers and listeners. It must be called "conf.yml" and sit beside the eevy binary file. Below is an example configuration file;

logs:
  event: stdout
  handler: stderr
  app: /var/log/eevy/app.log
  level: ERROR
sources:
  - type: sqs
    url: https://sqs.eu-west-1.amazonaws.com/999999999/lambda
    region: eu-west-1
  - type: http
    port: 8000
handlers:
  testSqs:
    type: sqs
    region: eu-west-1
    url: https://sqs.eu-west-1.amazonaws.com/999999999999/output
  testLambda:
    type: lambda
    region: eu-west-1
    function: test
  testSqs2:
    type: sqs
    region: eu-west-1
    url: https://sqs.eu-west-1.amazonaws.com/999999999999/output
listeners:
  "_":
    - testSqs
  application.*:
    - testLambda
  test.event2:
    - testSqs2

The above example creates two sources; an AWS SQS and starts listening on port 8000 for HTTP requests. There are three handlers defined which can be used throughout eevy. The "_" listener is a wild card and responds to every event received (this would make more sense if it was "*" however yaml doesn't like special characters at start of a key). It evokes the handlers that are defined it its array, in this example it places the events message received onto an AWS SQS queue via he "testSqs" handler. "application." invokes its handler when any event that begins with "application" is detected. Finally "test.event2" will only be called when exactly that event is revived. Without the trialling "" it will not respond to any event that has a sub event name eg "test.event2.anything".

Logging

Setting the logging level must be oe of the following string values;

• CRITICAL
• ERROR
• WARNING
• NOTICE
• INFO
• DEBUG

Sources

AWS SQS

Description

This listener pulls events from the specified AWS SQS queue.

Config

Name	Type	Description
type	string	This must be set to "sqs"
url	string	The URL for the SQS
region	string	The aws region it belongs to eg "eu-west-1"

HTTP

Description

This source listens on a specified port for HTTP connections. A POST request should be sent to "http://hostname:/event/". The body of the post request is treated as the message.

Config

Name	Type	Description
type	string	This must be set to "http"
port	int	The port number to listen on
bindIp	string	Ip address to bind to

Handlers

AWS SQS

Description

When a relevant event is received place its message section onto the supplied AWS SQS.

Config

Name	Type	Description
type	string	This must be set to "sqs"
url	string	The URL for the SQS
region	string	The aws region it belongs to eg "eu-west-1"
message	string	The body of the request sent to the listener

AWS Lambda

Description

This listener invokes an AWS Lambda function

Config

Name	Type	Description
type	string	This must be set to "lambda"
function	string	The name of the function to be invoked
region	string	The AWS region it belongs to eg "eu-west-1"
message	string	The body of the request sent to the listener

cli

Description

This listener performs a local system call

Config

Name	Type	Description
type	string	This must be set to "lambda"
bin	string	Binary to be called
args	[]string	Arguments to be passed in
timeout	int	Number of seconds for timeout (0 for none)
message	string	The body of the request sent to the listener

OAuth2

Description

Use this listener when sending events to an OAuth 2 end point such as the hevnly api.

Config

Name	Type	Description
type	string	This must be set to "oauth2"
clientId	string	OAuth2 client id to use during authentication
clientSecret	string	The AWS region it belongs to eg "eu-west-1"
scope	[]string	Array of scopes to use during authentication
tokenUrl	string	OAuth2 token URL
endPoint	string	URL to call after OAuth2 authentication
verb	string	("get" or "post") HTTP verb used when calling endpoint
message	string	The body of the request sent to the listener

Beanstalkd

Description

Places events into a beanstalkd tube.

Config

Name	Type	Description
type	string	This must be set to "beanstalkd"
host	string	The name of the beanstalkd hostname
port	uint	Which port number is beanstalkd listening on
tube	string	Which tube to put event into
message	string	The body of the request sent to the listener

Variables

Sometimes the end point of an OAuth call we want a handler to call is embedded in the event message. To allow this we can use variables. Variables are handler values that are surrounded by "${message.name}". The following example shows how this should be used; Event

{
    "event":"api.testSqs",
    "message":{"verb":"post","body":"test","url":"http:\/\/hevnly.dev\/img\/r55435730c954c\/resized\"}
}

Handler configuration

- type: oauth2
  clientId: testClientID
  clientSecret: testClientSecret
  scope:
    - oauth2
  tokenUrl: http://test.dev/oauth/v2/token
  endPoint: ${message.url}
  body: ${message.body}
  verb: ${message.verb}

These variables can be used in most handler configuration fields.

Events

An event is simply a json object that must have the following structure

{
    "event": "event.name",
    "message": {"desc": "json object with the associated events data"} 
}