Service Discovery and Configuration Management

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Service Discovery and Conﬁguration Management Puppet Labs Gareth Rushgrove Two speeds of conﬁguration

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@garethr

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Gareth Rushgrove

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Gareth Rushgrove

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This talk

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A quick introduction to Service Discovery Gareth Rushgrove

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Why it’s useful to have two speeds of conﬁguration Gareth Rushgrove

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An example of using Consul alongside Puppet Gareth Rushgrove

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Some brief thoughts about change control and autonomous systems Gareth Rushgrove

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What is Service Discovery?

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Gareth Rushgrove

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Service discovery is a key component of most distributed systems and service oriented architectures. Gareth Rushgrove http://jasonwilder.com/blog/2014/02/04/service-discovery-in-the-cloud/

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The problem seems simple at ﬁrst: How do clients determine the IP and port for a service that exist on multiple hosts? Gareth Rushgrove http://jasonwilder.com/blog/2014/02/04/service-discovery-in-the-cloud/

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Etcd, Consul, Zookeeper Gareth Rushgrove

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Hadoop uses Zookeeper Socketplane uses Consul CoreOS uses etcd Cloud Foundry uses Consul Cloud Foundry also uses etcd Kubernetes uses etcd Gareth Rushgrove

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Gareth Rushgrove Thanks to etcd for the graphics

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Gareth Rushgrove Thanks to etcd for the graphics

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Gareth Rushgrove Thanks to etcd for the graphics

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Gareth Rushgrove Jepsen

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Why now?

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Every organisation wants to move quicker Gareth Rushgrove

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Provisioning times are decreasing rapidly Gareth Rushgrove

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The number of applications, and instances of those applications, is increasing rapidly Gareth Rushgrove

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The number of systems administrators is probably going to stay the same. Sorry. Gareth Rushgrove

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Technology moving towards a cluster centric view rather than a host centric view Gareth Rushgrove

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Hard-coding everything doesn’t scale Gareth Rushgrove

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Some relevant technology you may have heard of Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Two speeds of conﬁguration

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Conﬁguration management tools tend to focus on upfront modelling, managing conﬁguration we know and want to control over time Gareth Rushgrove

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For example the version of a package or application, user permissions, security settings, system constrains Gareth Rushgrove

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Service discovery tools handle emergent conﬁguration which is a property of the running system Gareth Rushgrove

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For example load balancer and proxy backends, network and ﬁrewall routes as applications come and go Gareth Rushgrove

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Wait, but I want to deﬁne some of my network conﬁguration upfront Gareth Rushgrove

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Hence two speeds, model driven and emergent Gareth Rushgrove

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How to mix conﬁguration management and service discovery

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We’ll use Consul for this example Gareth Rushgrove

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We’ll also use Puppet Gareth Rushgrove

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First lets install Consul everywhere Gareth Rushgrove

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Gareth Rushgrove

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That’s it Gareth Rushgrove

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Gareth Rushgrove KyleAnderson/consul

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We can conﬁgure servers and clients using Hiera Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Consul nodes need to register with a server Gareth Rushgrove

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Gareth Rushgrove

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Populating the Consul service registry Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove Consul dashboard

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Create your own types Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Using information from Consul in Puppet Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove lynxman/hiera_consul

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Trigger Puppet when something pertinent changes Gareth Rushgrove

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Gareth Rushgrove

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Gareth Rushgrove Demo time

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Same example possible with a bit of hacking for etcd Gareth Rushgrove

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Gareth Rushgrove garethr/hiera-etcd

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Gareth Rushgrove KyleAnderson/etcd

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Advantages Changes happen quickly, but without losing the ability to address conﬁguration drift Gareth Rushgrove

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Advantages Reduce complexity of watchers, all changes lead to a Puppet run Gareth Rushgrove

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Advantages All changes to conﬁguration, however triggered, are tracked in one place Gareth Rushgrove

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Advantages Deﬁne all watchers in code Gareth Rushgrove

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Advantages Reduce duplication, same code runs for new and existing instances Gareth Rushgrove

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Bonus distributed conﬁguration Gareth Rushgrove

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Replace lots of identical local ﬁles on disk with distributed key/values Gareth Rushgrove