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Advanced DNS with Consul Service Discovery

Advanced DNS with Consul Service Discovery

This talk covers why only DNS is not ideal in modern day infrastructure where microservices embrace rapid deployments of applications. HashiCorp Consul let's easily manage microservices with a few service discovery features!

Edgaras Apšega

October 24, 2019

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  1. Advanced DNS with Consul Service Discovery Edgaras Apšega Lead IT

    Systems Engineer Adform @apsega Cloud Native Lithuania
  2. Agenda Why DNS is not perfect? Why do we need

    Service Discovery? What problems does HashiCorp Consul solve? Cloud Native Lithuania
  3. DNS

  4. TERMINAL > dig +short apsega.lt > curl -sI | head -1 HTTP/1.1 200 OK > curl -sI | head -1 HTTP/1.1 503 Service Temporarily Unavailable DNS query DNS balances queries between domain name records; Are all servers under DNS responding correctly?
  5. Eureka Netflix Open Source Consul HashiCorp Open Source and Enterprise

    ZooKeeper Apache Open Source Most popular products
  6. Consul architecture All the agents that are in a datacenter

    participate in a gossip protocol; The servers in each datacenter are all part of a single Raft peer set.
  7. HashiCorp Consul features 1. Service Discovery (DNS with 0 TTL

    or HTTP API with rich metadata); 2. Health Checking (HTTP, TCP, scripts); 3. Prepared Queries (failover to other datacenters based on RTT); 4. Key/Value Store (dynamic configuration, leader election); 5. Service Mesh (auto mTLS, Intentions);
  8. Service Discovery With Health Checks CODE EDITOR { "service": {

    "name": "webserver", "tags": ["production", “nginx”], "port": 80, "check": { "interval": "5s", "http": "http://localhost:80", "timeout": "1s" } } }
  9. TERMINAL > dig +short webserver.service.consul > dig +short

    production.nginx.service.consul > dig +short nginx.service.eu-west-1.consul DNS interface 1. Simple service query; 2. Service query with tags; 3. Service query for specific datacenter.
  10. Consul template with Nginx 1. Nginx upstream configuration 2. Upstream

    Consul template CODE EDITOR upstream from_consul { <…> include /opt/consul-template.d/from_consul_nginx_upstreams.conf; <…> } {{ range service ”webserver" }} server {{ .Address }}:{{ .Port }} max_fails=1 fail_timeout=15s weight=1; {{ else }} server max_fails=1 fail_timeout=15s weight=1; {{ end }}
  11. Consul with HAProxy CODE EDITOR resolvers mydns nameserver dns1

    accepted_payload_size 8192 # allow larger DNS payloads backend webservers balance roundrobin server-template web _webserver._tcp.service.consul resolvers mydns check init-addr none
  12. 2,300+ Registered nodes 690+ Registered services 700+ DNS Queries per

    second 11 Clusters 6 Production regions Between 8 datacenters