Service Discovery in Distributed System with DCOS & Kubernettes. - Sahil Sawhney
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The document discusses the need for service discovery in distributed systems, highlighting its importance for communication among dynamic services. It explains the two types of service discovery: client-side and server-side, along with their respective advantages and disadvantages. Additionally, it provides insights into service discovery implementations in DC/OS and Kubernetes, including DNS-based and load balancing methods.
Service Discovery in Distributed System with DCOS & Kubernettes. - Sahil Sawhney
- 2. Agenda ➔ Why need a distributed environment ➔ What is service discovery ➔ Why do we need service discovery ➔ Service Discovery in DCOS ➔ Service discovery in Kubernetes ➔ Conclusions and observations
- 3. Why Need A Distributed Environment ➔ ELK stack ➔ Prometheus ➔ Pager Duty ➔ Web Servers ➔ Backend Servers ➔ Databases ◆ Sql ◆ NoSql ➔ Streaming Jobs ➔ Kafka Queues ➔ Zookeeper And Many More….
- 4. But What About …..
- 5. There Need to be a way …. We need to answer following : ➔ What mechanism allows services to be called even with constantly changing hosts in a distributed environment. ➔ How are these services (like microservices) communicating with each other internally ➔ How the external request/response mechanism works in a distributed environment
- 6. Service Discovery To The Rescue All the questions we just raised could be answered by having a proper service discovery mechanism. Service discovery could be defined as a process of finding the network location of a running service. In case of distributed systems, the host alloted to a service are dynamic and keeps on changing. Service discovery make sures that the dynamic nature of application deployment does not effects the reachability/availability of the application.
- 7. Types Of Service Discovery Service discovery is broadly of 2 types ➔ Client Side Service Discovery ➔ Server Side Service Discovery
- 8. Client Side Service Discovery
- 9. Concluding Advantages ➔ Except for the service registry, there are no other moving parts ➔ Intelligent custom application‑specific load‑balancing decisions Disadvantages ➔ It couples the client with the service registry ➔ Need to implement discovery logic for each programming language and framework used by the service clients.
- 10. Server Side Service Discovery
- 11. Concluding Advantages ➔ Details of discovery are abstracted away from the client ➔ Clients simply make requests to the load balancer. Disadvantages ➔ Unless the load balancer is provided by the deployment environment, it is yet another highly available system component that you need to set up and manage.
- 12. What is DCOS / Kubernetes All About ? DEFINITION A distributed system is a network that consists of autonomous computers that are connected using a distribution middleware. They help in sharing different resources and capabilities to provide users with a single and integrated coherent network. DCOS(Marathon) and Kubernetes are the the leading distributed orchestration platforms.
- 13. Service Discovery In Kubernetes and DCOS ➔ Deployment environments such as Kubernetes and Marathon uses server side service discovery and run a proxy on each host in the cluster. ➔ The proxy plays the role of a server‑side discovery load balancer. ➔ In order to make a request to a service, a client routes the request via the proxy using the host’s IP (public/master node) address and the service’s assigned port. ➔ The proxy then transparently forwards the request to an available service instance running somewhere in the cluster.
- 14. Implementing Service Discovery In DCOS In DCOS service discovery / load balancing could be implemented in following ways DNS based Service Discovery (Used Internally in distributed cluster) ➔ Mesos DNS ➔ DCOS DNS Load Balancing based Service Discovery ➔ External and Internal Marathon-LB ➔ Virtual IP Addresses (VIPs) ➔ Edge-LB (Enterprise)
- 15. Demo Time
- 16. Mesos DNS VS DCOS DNS Mesos DNS ➔ All the fully qualified domain name (FQDNs) have the top level domain (TLD) of .mesos ➔ Only master have the information about all FQDNs ➔ Not a recommended choice. DCOS DNS ➔ All the fully qualified domain name (FQDNs) have the top level domain (TLD) of .directory ➔ All the nodes have the information about all FQDNs ➔ Highly Available.
- 17. VIP Addresses VS External Marathon-LB Virtual IP Addresses ➔ Used to load balance services inside the DCOS VPN ➔ Services cannot be accessed from outside the DCOS cluster ➔ Generally TCP service ports are accessed ➔ Specified via labels like VIP_0, VIP_1, etc. External Marathon-LB ➔ Used to load balance services Outside the DCOS VPN ➔ Used to route the traffic like clients REST requests. ➔ Http and Https ports are accessed. ➔ Specified via HAPROXY_GROUP
- 18. Thank You