The document discusses service discovery using Consul, highlighting its importance in transitioning from monolithic to microservices architecture. It outlines the challenges associated with microservices, such as monitoring and configuration management, and introduces practical service discovery goals. The architecture of Consul, including self-registration, service health checks, and various client models, is explained, along with links to related resources and a planned demo event.

1. Service Discovery w/
Consul
Ali Demirsoy @kloia

2. “Digital Transition Accelerator“
33 Queen St, London EC4R
1AP, United Kingdom
blog.kloia.com
@kloia_com
AND Binası 10-12, 34752
Kozyatagi/Istanbul, Turkey
kloia.com
Cloud
DevOps
Test Automation
Microservices

3. • History
• Microservices & Service Discovery
• Consul
• Demo
Agenda

4. • Physical Servers & DNS
History

5. • Load balancer & Many Physical Servers
History

6. • Virtualization
• Web/App/Db layers
• Create/Destroy in minutes
• Scale up/down dynamically
• Manually configure?
History

7. • Containerization & Microservices
• Create/Destroy in ms
• Hundreds of Services
• Impossible to manage manually
History

8. • Monolith: Hard to maintain,
troubleshoot, evolve
• Microservice: Independent,
scalable, simple
Monolith to Microservices

9. Challenges:
o Monitoring
o Logging
o Version and Configuration Management
o Distributed Transactions
o Service Discovery
o …
Microservices not a free lunch

10. • Start services in any order
• Destroy services with confidence
• Restart servers safely
• Reconfigure services easily
Practical Goals

11. • Can find services
• Can avoid and handle unhealthy services
• Can be configured externally
Robust Systems

12. • Database of available service instances
• Two approaches:
o Self Registration
o Third Party Registration
• Heartbeat vs Polling
Service Registry

13. • Straightforward
• Smart clients
• Clients and Service Registry
coupled
Client Side Discovery

14. • Dumb clients
• Load balancer: SPOF
Server Side Discovery

15. • High Available, Distributed K/V store
• Service Discovery. DNS and HTTP Interface
• Flexible Health Checking
• Multi Datacenter
• Open Source
Consul

16. Architecture

17. • Leader Election
• Replicated Logs
• Quorum
• http://thesecretlivesofdata.com/raft
Raft Consensus Algorithm

18. • Rest  /v1/catalog/services
• DNS  dig @127.0.0.1 -p 8600 testConsulApp.service.consul SRV
• CLI  consul kv get myAppConfig
• Web UI 
Consul Interface

19. • Register a service: PUT /agent/service/register
• List services : GET /agent/services
• Maintenance mode: /agent/service/maintenance/:service_id
• Health: GET /health/node/:node
• K/V store: /kv/:key
Consul Rest API

20. Defining Watches

21. Defining Locks
• host1 $ consul lock service/redis/lock redis-server
• host2 $ consul lock service/redis/lock redis-server
• Active/Passive Architecture

22. Defining Locks

23. • Zookeeper
• Etcd
• Netflix Eureka
• Marathon-lb
Other Tools

24. Demo

25. Istanbul HashiCorp Meetup
https://www.meetup.com/Istanbul-
HashiCorp-Meetup/
20, September 2018
Radisson, Sisli
http://devopsdays.istanbul