Session affinity
Session affinity is a traffic-routing policy that directs successive requests from a client or session to the same backend instance.
Kubernetes in Action, Second Edition
Cookie-based session affinity is a traffic-routing policy that uses an HTTP cookie to keep a client associated with the same backend instance.
- How it is used
- Routes repeated HTTP requests from one client to the same backend through an Ingress.
- How deep it goes
- Explains layer boundaries, annotations, cookie naming, manifest configuration, and curl verification without developing controller internals.
- Examples
- Uses Nginx annotations, a named SESSION_COOKIE, Set-Cookie output, and repeated curl requests.
- What you can do after
- Operate/configure cookie affinity by applying an Nginx Ingress manifest and replaying the returned Cookie header.
Read how Kubernetes in Action, Second Edition explains session affinity →
Learn Docker in a Month of Lunches, Second Edition
A sticky session is session affinity that routes repeated requests from a client to the same service instance when possible.
- How it is used
- Routes a client back to one container when an application depends on instance-local session state.
- How deep it goes
- Explains the cookie-based routing mechanism and demonstrates it with scaled containers, but does not detail service-label syntax.
- Examples
- Demonstrates a scaled who-am-I application, repeated curl requests, and a c.txt cookie jar.
- What you can do after
- Configure and verify sticky sessions in Traefik while comparing cookie-persisted routing with ordinary load balancing.
Read how Learn Docker in a Month of Lunches, Second Edition explains session affinity →
Related concepts
- canary deploymentused by · A canary deployment is a release strategy that exposes a change to a limited portion of users, traffic, or infrastructure before expanding it more broadly.
- serviceconfigures · A Kubernetes Service is an API resource that provides stable network access and service discovery for a changing set of Pods or other specified destinations.
- statefulnessuses · Statefulness is the property of a system or operation whose behavior or results depend on information retained or changed across interactions or executions.
- annotationconfigured by · A Kubernetes annotation is key-value metadata attached to an object for storing non-identifying descriptive, configuration, or operational information.
- Traefikimplements · Traefik is an open-source dynamic reverse proxy and load balancer that configures routing using service discovery and runtime metadata.
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