Getting Started With Routemaster

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In this post I want to cover installing and publishing events to the excellent RouteMaster event bus.

Routemaster is an opinionated event bus over HTTP, supporting event-driven / representational state notification architectures.

RouteMaster uses RabbitMQ under the hood.

Routermaster

First of all install and start RouteMaster:

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hub clone HouseTrip/routemaster

cd routermaster

bundle install 

foreman start

RabbitMQ

Install and start RabbitMQ:

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brew install rabbitmq

rabbitmq-server

If rabbitmq-server is not found make sure /usr/local/sbin is in your $PATH.

Create a Virtual Host

  • Visit http://localhost:15672/#/
  • Login with guest/guest (the default user for RabbitMQ)
  • Go to Admin => Virtual hosts => add a new virtual host called routemaster.development
  • The virtual host can be changed in .env, see ROUTEMASTER_AMQP_URL.

Add a user to the Virtual Host

Add the admin user with full permissions to the newly created virtual host.

Setup port and SSL proxy

Since Routemaster only excepts SSL connections we need to jump through a few hoops.

We want this proxying:

https://localhost:443 –> http://localhost:80 –> http://routemaster.dev:15672

15672 is the default port which RouteMaster binds to and can be changed in .env.

  • Forward port 443 (HTTPS) to 80 (HTTP)
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gem install tunnels
rbenv rehash
sudo tunnels 127.0.0.1:443 127.0.0.1:80
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brew install pow
# follow the post install instructions...

echo 17890 > ~/.pow/routemaster

pow

Publish an Event

Now the fun starts…

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gem install routemaster-client
irb

In our irb session we are going to try and connect to RouteMaster:

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require 'routemaster/client'

client = Routemaster::Client.new(url: 'https://routemaster.dev', uuid: 'demo')

The UUID demo is already known to RouteMaster see ROUTEMASTER_CLIENTS in .env.

Troubleshooting

If you get a Timeout error most likely the port proxying is not setup correctly. Ensure pow is running.

A cannot connect to bus error is most likely an authentication issue between RouteMaster and RabbitMQ. Check the output of foreman to confirm, you might see something like Bunny::PossibleAuthenticationFailureError. If so make sure the virtual host is setup and the guest user is assigned with full permissions:

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rabbitmqctl list_users
rabbitmqctl list_user_permissions guest

# routemaster.development .* .* .*

Sending a create event

RouteMaster only supports a small set of event types: create, update, delete and noop.

If the client connected try publishing an event:

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client.created('orders', 'https://app.example.com/orders/1') # => nil

The first argument is the topic, which is automatically created if it does not exist. There should be one topic per domain concept. The URL is where the subscribers can fetch a representation of the created entity.

You should see output in foreman since RouteMaster logs to STDOUT by default, e.g. POST /topics/widgets HTTP/1.1" 200.

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