Reaching pods.
WHAT A SERVICE PROVIDES
A stable name and address for a changing set of pods.
HOW PODS ARE SELECTED
By label.
WHAT THE TYPES ARE
Cluster-internal, reachable only inside Node port, exposed on every node Load balancer, provisioned by the cloud provider External name, an alias to another address
WHAT TO USE INTERNALLY
Cluster-internal, which is the default.
WHAT TO USE FOR EXTERNAL TRAFFIC
An ingress, usually, rather than a service per application.
WHY
One entry point handles hostnames, paths and certificates for everything.
WHAT AN INGRESS CONTROLLER IS
The component actually implementing the routing.
WHAT TO REMEMBER
Ingress objects do nothing without a controller installed.
HOW SERVICE DISCOVERY WORKS
Cluster resolution, where the service name resolves to its address.
WHAT NAME TO USE FROM ANOTHER NAMESPACE
The service name, the namespace, and the cluster suffix.
WHAT A HEADLESS SERVICE PROVIDES
Direct pod addresses, rather than one virtual address.
WHERE THAT IS NEEDED
Databases and clustered applications needing individual members.
WHAT TO CHECK WHEN TRAFFIC DOES NOT ARRIVE
Whether the service has endpoints Whether labels match Whether the pod is ready
WHAT NO ENDPOINTS MEANS
Either no matching pods, or none ready.
