Krakow
"KRAKOW! KRAKOW! Two direct hits!"
Spiff
require 'krakow'
producer = Krakow::Producer.new(
:host => 'HOST',
:port => 'PORT',
:topic => 'target'
)
producer.write('KRAKOW!', 'KRAKOW!')Zargons
require 'krakow'
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship'
)
consumer.queue.size # => 2
2.times do
msg = consumer.queue.pop
puts "Received: #{msg}"
consumer.confirm(msg.message_id)
endWhat is this?
It's a Ruby library for NSQ using Celluloid under the hood.
Information and FAQ that I totally made up
Max in flight for consumers is 1, regardless of number of producers
Yep, that's right. Just one lowly message at a time. And that's probably not what you want, so adjust it when you create your consumer instance.
require 'krakow'
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:max_in_flight => 30
)Clean up after yourself
Since Celluloid is in use under the hood, and the main interaction points are
Actors (Consumer and Producer) you'll need to be sure you clean up. This simply
means terminating the instance (since falling out of scope will not cause it to be
garbage collected).
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:max_in_flight => 30
)
# do stuff
consumer.terminatePlease make it shutup!
Sure:
Krakow::Utils::Logging.level = :warn # :debug / :info / :warn / :error / :fatalWhy is it forcing something called an "unready state"?
Because forcing starvation is mean. We don't want to be mean, so we'll ensure we are consuming from all registered connections.
I just want to connect to a producer, not a lookup service
Fine!
consumer = Krakow::Consumer.new(
:host => 'HOST',
:port => 'PORT',
:topic => 'target',
:channel => 'ship',
:max_in_flight => 30
)Great for testing, but you really should use the lookup service in the "real world"
Backoff support
NSQ has this backoff notion. It's pretty swell. Basically, if messages from a specific producer get re-queued (fail), then message consumption from that producer is halted, and slowly ramped back up. It gives time for downstream issues to work themselves out, if possible, instead of just keeping the firehose of gasoline on. Neat.
By default backoff support is disabled. It can be enabled by setting the :backoff_interval
when constructing the Consumer. The interval is in seconds (and yes, floats are allowed
for sub-second intervals):
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:max_in_flight => 30,
:backoff_interval => 1
)I need TLS!
OK!
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:connection_options => {
:features => {
:tls_v1 => true
}
}
)I need Snappy compression!
OK!
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:connection_options => {
:features => {
:snappy => true
}
}
)NOTE: snappy support requires the snappy gem and is not provided by default, so you will need to ensure it is installed either on the system, or within the bundle.
I need Deflate compression!
OK!
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:connection_options => {
:features => {
:deflate => true
}
}
)I want to use TLS based authentication!
OK!
consumer = Krakow::Consumer.new(
:nsqlookupd => 'http://HOST:PORT',
:topic => 'target',
:channel => 'ship',
:connection_options => {
:features => {
:tls_v1 => true
},
:config => {
:ssl_context => {
:certificate => '/path/to/cert',
:key => '/path/to/key'
}
}
}
)Running the tests
Run them all!
bundle exec ruby test/run.rb
Or, run part of them:
bundle exec ruby test/specs/consumer_spec.rb
NOTE: the specs expect that nsqd and nsqlookupd are available in $PATH
It doesn't work
Create an issue on the github repository
It doesn't do x
Create an issue, or even better, send a PR.
Info
- Repo: https://github.com/chrisroberts/krakow
- Docs: http://code.chrisroberts.org/krakow
- IRC: Freenode @ spox
Contributors
- Pete Hopkins (@phopkins)
- Sam Phillips (@i2amsam)
- Brendan Schwartz (@bschwartz)
- Thomas Holmes (@thomas-holmes)
- Jeremy Hinegardner (@copiousfreetime)