Getting Started with Consul Ramit Surana @ramitsurana /in/ramitsurana 

Agenda • Introduction • Consul Architecture • Raft Algorithm • Comparisons • Setup • How to use it ? • Bootstrapping and DNS • Jespen Testing • Consul on AWS 

Introduction • Tool for discovering and configuring a variety of different services in your infrastructure. • Built on Golang. • 3 basic ports: 8400 - RPC 8500 - HTTP 8600 - DNS 

Features • Service Discovery − Using either DNS or HTTP, applications can easily find the services they depend upon. • Health Check Status − It can provide any number of health checks. It is used by the service discovery components to route traffic away from unhealthy hosts. • Key/Value Store − It can make use of Consul's hierarchical key/value store for any number of purposes, including dynamic configuration, feature flagging, coordination, leader election, etc. • Multi Datacenter Deployment − Consul supports multiple datacenters. It is used for building additional layers of abstraction to grow to multiple regions. • Web UI − Consul provides its users a beautiful web interface using which it can be easy to use and manage all of the features in consul. 

Consul Architecture 

Raft Algorithm 

Comparison between etcd, zookeeper & consul 

Setup • Download consul from https://www.consul.io/downloads.html • Extract binary package from the downloaded folder. $ cd Downloads $ chmod +x consul $ sudo mv consul /usr/bin/ 

Consul-Template • Daemon that queries the Consul instance and updates any number of specified templates on the file system. • Download & Extract from https://releases.hashicorp.com/consul- template/. $ cd Downloads $ chmod +x consul-template $ sudo mv consul-template /usr/share/bin/ 

Consul-UI • Divided into three important parts, which are − ACL − Set of Rules to easily lock your clusters easily Datacenter − Enables you to easily manage datacenters and work out with your cluster. Nodes − Quick update on the nodes that Consul cluster is using $ mkdir /opt/consul-ui $ cd /opt/consul-ui $ wget https://releases.hashicorp.com/consul/0.7.2/consul_0.7.2_web_ui.zip $ unzip consul_0.7.2_web_ui.zip $ sudo consul agent -dev -ui -data-dir /tmp/consul 

How to use it ? • //Running Consul $ sudo consul agent –dev –data-dir=/tmp/consul • // Listing members $ consul members • // Joining Nodes $ consul join • // Using Docker $ docker run –p 8400:8400 –p 8500:8500 –p 8600:53/udp-h node1 progrium/consul - server -bootstrap 

How to use it ? • //Running Consul UI $ docker run –p 8400:8400 –p 8500:8500 –p 8600:53/udp-h node1 progrium/consul - server –bootstrap –ui-dir /ui • // Digging $ dig @127.0.0.1 -p 8600 web.service.consul • // Monitor $ consul monitor • // Watch $ consul watch –type=service –service=consul 

How to use it ? • //Registering External Services on Consul $ sudo curl -X PUT -d '{"Datacenter": "dc1", "Node": "amazon", "Address": "www.amazon.com", "Service": {"Service": "shop", "Port": 80}}' http://127.0.0.1:8500/v1/catalog/register • // Removing External Service $ curl -X PUT -d '{"Datacenter": "dc1", "Node": "amazon"}' http://127.0.0.1:8500/v1/catalog/deregister • // Info $ sudo consul info 

Bootstrapping & DNS • Bootstrapping can be divided into 2 parts: Automatic Bootstrapping - Automatically configured to detect, identify and join nodes. Manual Bootstrapping – Manual addition of Nodes using below cmd $ consul join • DNS is served from port 53. The DNS forwarding can be done using BIND, dnsmasq and iptables. • Consul DNS interface makes the port information for a service available via the SRV records. • If Dnsmasq is installed - $ dig web.service.consul 

Jespen Testing • Tool written to test the partial tolerance and networking in any system. • Written in Clojure. • Tests the system by creating some random operations on the system. • For demo, Jepsen testing requires a huge level of cluster formation with database systems and hence is out of scope for demo 

Consul on AWS • URL: https://aws.amazon.com/quickstart/archit ecture/consul/ • create the following components − • A VPC with public and private subnets across three Availability Zones. • A Seed Consul server and a Seed client along with two Auto Scaling groups. • You can choose to create 3, 5, or 7 servers. The number of clients is set to three by default, but it is user-configurable. • Dnsmasq, which is installed and configured for Consul as part of the installation. • A Consul cluster using bootstrap_expect option. 

Thank You :)