A Ruby client for etcd with JSON Model mapper, recursive Reader/Writer, rspec testing support.
Inspired by and mostly compatible with https://github.com/ranjib/etcd-ruby, extended with additional features:
Use the LOG_LEVEL=debug env to log all Kontena::Etcd::Client requests:
D, [2017-01-03T16:03:33.088421 #5247] DEBUG -- Kontena::Etcd::Client: get /kontena/test/foo {}: error Kontena::Etcd::Error::KeyNotFound /kontena/test/foo@0: Key not found
D, [2017-01-03T16:03:33.107597 #5247] DEBUG -- Kontena::Etcd::Client: get /kontena/test/ {}: get /kontena/test/@1: test1/ test2/
D, [2017-01-03T16:03:33.127267 #5247] DEBUG -- Kontena::Etcd::Client: set /kontena/test/quux {:prevExist=>false, :value=>"{\"quux\": false}"}: create /kontena/test/quux@1: {"quux": false}
D, [2017-01-03T16:03:33.425220 #5247] DEBUG -- Kontena::Etcd::Client: watch /kontena {:wait=>true, :recursive=>true, :waitIndex=>1799, :timeout=>1.0}: set /kontena/test1@1799: {"test":1}
D, [2017-01-03T16:03:33.428694 #5247] DEBUG -- Kontena::Etcd::Client: watch /kontena {:wait=>true, :recursive=>true, :waitIndex=>1800, :timeout=>1.0}: delete /kontena/test1@1800:
Use Kontena::Etcd::Client.from_env to automatically configure the client from the ETCD_ENDPOINT environment variable.
etcd version 2.3 /v2/keys API
getsetrefreshdeletepostwatch
Atomically follow a key prefix, synchronizing the initial etcd nodes using a recursive get, and then applying recursive watch events to maintain the etcd nodes.
#!/usr/bin/env ruby
require 'kontena/etcd'
reader = Kontena::Etcd::Reader.new('/kontena')
reader.run do |nodes|
puts nodes.map{|node| "#{node.key}=#{node.value}"}.join ' '
endGives the following output:
I, [2017-01-03T16:12:40.865194 #6058] INFO -- Kontena::Etcd::Reader: set /kontena/test1: {"key":"/kontena/test1","value":"test1","modifiedIndex":1812,"createdIndex":1812,"expiration":null,"ttl":null,"dir":null,"nodes":null}
/kontena/test1=test1
I, [2017-01-03T16:12:44.942192 #6058] INFO -- Kontena::Etcd::Reader: set /kontena/test2: {"key":"/kontena/test2","value":"test2","modifiedIndex":1813,"createdIndex":1813,"expiration":null,"ttl":null,"dir":null,"nodes":null}
/kontena/test1=test1 /kontena/test2=test2
I, [2017-01-03T16:12:48.289306 #6058] INFO -- Kontena::Etcd::Reader: set /kontena/test1: {"key":"/kontena/test1","value":"test1-v2","modifiedIndex":1814,"createdIndex":1814,"expiration":null,"ttl":null,"dir":null,"nodes":null}
/kontena/test1=test1-v2 /kontena/test2=test2
I, [2017-01-03T16:12:52.488216 #6058] INFO -- Kontena::Etcd::Reader: delete /kontena/test2: {"key":"/kontena/test2","value":null,"modifiedIndex":1815,"createdIndex":1813,"expiration":null,"ttl":null,"dir":null,"nodes":null}
/kontena/test1=test1-v2
I, [2017-01-03T16:13:14.723846 #6058] INFO -- Kontena::Etcd::Reader: set /kontena/test2: {"key":"/kontena/test2","value":"test2-expiring","modifiedIndex":1816,"createdIndex":1816,"expiration":"2017-01-03T14:13:24.721135508Z","ttl":10,"dir":null,"nodes":null}
/kontena/test1=test1-v2 /kontena/test2=test2-expiring
I, [2017-01-03T16:13:25.178353 #6058] INFO -- Kontena::Etcd::Reader: expire /kontena/test2: {"key":"/kontena/test2","value":null,"modifiedIndex":1817,"createdIndex":1816,"expiration":null,"ttl":null,"dir":null,"nodes":null}
/kontena/test1=test1-v2
Maintain a set of nodes in etcd, automatically adding and removing nodes when updated.
Supports TTL for automatic expiry on writer crashes, with periodic refreshing to maintain the nodes. The refresh operation also serves to detect any write conflicts.
Map Ruby objects from JSON objects in etcd using class mixins/definitions:
class Example
include Kontena::JSON::Model
include Kontena::Etcd::Model
etcd_path '/kontena/example/:foo'
json_attr :bar
endAllows operations such as the following:
Example.delete
Example.create('foo1', bar: 'bar2')
Example.each do |example|
puts "#{example.foo}=#{example.bar}"
end
example = Example.get('foo1')With resulting output:
D, [2017-01-04T13:22:02.004864 #7431] DEBUG -- Kontena::Etcd::Client: delete /kontena/example/ {:recursive=>true}: delete /kontena/example/@1450:
D, [2017-01-04T13:22:02.011548 #7431] DEBUG -- Kontena::Etcd::Client: set /kontena/example/foo1 {:prevExist=>false, :value=>"{\"bar\":\"bar2\"}"}: create /kontena/example/foo1@1451: {"bar":"bar2"}
D, [2017-01-04T13:22:02.012594 #7431] DEBUG -- Kontena::Etcd::Client: get /kontena/example/ {}: get /kontena/example/@1451: foo1
foo1=bar2
D, [2017-01-04T13:22:02.013462 #7431] DEBUG -- Kontena::Etcd::Client: get /kontena/example/foo1 {}: get /kontena/example/foo1@1451: {"bar":"bar2"}
Includes RSpec support for writing tests against etcd, allowing specs to expect on the resulting etcd modifications.
Tests can be run using either an internal fake etcd API implementation, or a real etcd server.
The fake etcd server collects a log of any operations that modify the fake etcd store.
When running against a real etcd server, the modified? and logs helpers use the X-Etcd-Index and recursive watches to find any operations performed by the example.
require 'rspec'
require 'kontena/etcd/rspec'
describe Example do
it "Reads a node from etcd", :etcd => true do
etcd_server.load!(
'/kontena/example/foo1' => {'bar' => 'bar2'},
)
expect(described_class.get('foo1').bar).to eq 'bar2'
expect(etcd_server).to_not be_modified
end
it "Writes itself to etcd", :etcd => true do
described_class.create('foo1', bar: 'bar2')
expect(etcd_server).to be_modified
expect(etcd_server.logs).to eq [
[:create, '/kontena/example/foo1'],
]
expect(etcd_server.list).to eq Set.new([
'/kontena/',
'/kontena/example/',
'/kontena/example/foo1',
])
expect(etcd_server.nodes).to eq(
'/kontena/example/foo1' => {'bar' => 'bar2'},
)
end
endWhen running against the fake etcd server, additional behavior such as TTL expiration can be tested:
describe Kontena::Etcd do
# Mocking node expiry only works against the fake etcd server
it "Expires a node from etcd", :etcd => true, :etcd_fake => true do
etcd.set('/kontena/test', 'test-value', ttl: 30)
expect(etcd.get('/kontena/test')).to have_attributes(value: 'test-value')
etcd_server.tick! 30
expect{etcd.get('/kontena/test')}.to raise_error(Kontena::Etcd::Error::KeyNotFound)
end
it "Refreshes a node in etcd", :etcd => true, :etcd_fake => true do
etcd.set('/kontena/test', 'test-value', ttl: 30)
etcd_server.tick! 20
etcd.refresh('/kontena/test', 30)
etcd_server.tick! 20
expect{etcd.get('/kontena/test')}.to_not raise_error
etcd_server.tick! 10
expect{etcd.get('/kontena/test')}.to raise_error(Kontena::Etcd::Error::KeyNotFound)
end
end- #4 The tests are currently hardcoded to assume a
/kontenaprefix for all keys
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