How deeply does Kubernetes in Action, Second Edition cover SRV record?

Explains the record format, lookup commands, named ports, and StatefulSet usage, while deferring general DNS implementation details.

SRV record

As explained in Kubernetes in Action, Second Edition

An SRV record is a DNS record that identifies the host and port for a service, along with its protocol and priority information.

An SRV record is a DNS record that identifies a service’s protocol, port, target host, and priority information. In Kubernetes, each named Service port receives an SRV record in the cluster DNS, allowing clients to discover how to connect without hard-coding port details. section 11.4 section 11.4.1

Kubernetes service discovery uses SRV records in these ways:

A smart client can query a Service’s SRV records to discover the ports it provides. section 11.4.1
Named ports produce names in the form _port-name._port-protocol.service-name.namespace.svc.cluster.local. section 11.4.1
A headless Service associated with a StatefulSet gives stateful Pods SRV records that clients can use to discover each Pod’s address and port. section 16.1.5

Looking up a named Service port

Run a temporary tools Pod, then query the SRV record for the http port: kubectl run -it --rm dns-test --image=giantswarm/tiny-tools, followed by nslookup -query=SRV _http._tcp.kiada. The result identifies TCP port 80 on the kiada Service.

MongoDB discovery through SRV

A MongoDB client can use mongodb+srv://quiz-pods.kiada.svc.cluster.local instead of listing every replica address and port. The client performs an SRV lookup for _mongodb._tcp.quiz-pods.kiada.svc.cluster.local. section 16.1.5

How Kubernetes in Action, Second Edition covers it

Cover of Kubernetes in Action, Second Edition

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Related concepts

serviceproduced by · 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.
port numberproduced by · A port number is a numeric transport-layer identifier that directs network traffic to a service or application endpoint on a host.
headless serviceproduced by · A headless Service is a Kubernetes Service without a cluster IP that exposes its backing pod addresses directly through DNS.
DNS recordkind of · A DNS record is a structured Domain Name System entry associating a domain name with information such as an address, service target, or administrative value.
MongoDBuses · MongoDB is a document-oriented database management system that stores data as BSON documents, typically organized into collections.

This explainer was generated by Manning's knowledge graph from the text of Kubernetes in Action, Second Edition. The section links point to the parts of the book it draws on.