1. SERF@DEVOPS PUNE
RAHUL KHENGARE

2. Agenda
 What is Serf
 Installation
 Get Used To
 Use Cases
 Demo
 Limitations

3. Target Audience
 Having some knowledge of cluster environment
 Managed Clusters environment
 Eager to Learn SERF

4. SERF (By Hashicorp)
 OPEN SOURCE
 Decentralized
 Fault-tolerant
 Highly Available
 Uses Gossip Protocol to communicate with nodes
 Extremely Light Weight (5-10 MB Memory Footprint)
 Available for Linux, Mac OS X, and Windows

5. SERF USED FOR
 Cluster Membership Management
 Failure Detection and Recovery
 Event Propagation
 Orchestration

6. Installation
 Download SERF from https://www.serfdom.io/downloads.html
 Unzip and put binary in /usr/local/bin or /usr/bin folder (in LINUX)

7. SERF AGENT
 Core process
 Maintains membership information
 Propagates events
 Invokes event handlers
 Detects failures
 Run on every node that is part of cluster

8. RUN SERF AGENT
 SERF AGENT

9. Cluster Membership Management
 JOIN CLUSTER
 CLUSTER STATUS
 LEAVE CLUSTER
 CLUSTER STATUS

10. Failure Detection and Recovery
 MEMBER FAILED
 RECOVER MEMBER

11. Custom Event Propagation
 Dispatches a custom user event
 Nodes in the cluster listen custom events
 Reacts to them
 Execute Event Handlers
 Doesn’t send response back to originator

12. Event Handler Script

13. Custom Event Propagation
 Event Handler Execution
 Dispatch Custom User Event

14. SERVICE ORCHESTRATION
 Dispatches a query
 Nodes in the cluster listen query
 Reacts to them
 Execute Event Handlers
 Send response back
 Gathering Responses at originator

15. USE CASES
 Webservers and load balancers
 Memcached and Redis clusters
 Triggering deployments
 Updating DNS records
 Simple Observability
 A Building Block for Service Discovery

16. DEMO
 Setting up high availability configuration(Webserver)
Serf1
eth0
172.26.126.82
VIP
172.26.126.84
Apache
Serf2
eth0
172.26.126.74
SERF AGENT SERF AGENT
Apache
GOSSIP PROTOCOL

17. Limitations
 Under heavy development
 Events are eventually consistent
 Payload size is limited
 Queries may not be delivered to all nodes
 Responses and acknowledgements may not be receive by query originator

18. ANY QUESTIONS?

19. Thank You!!!