Understanding Kubernetes Services, Ingress, and Networking
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Key takeaway
This article will help you understand how Kubernetes networking works—from internal service discovery to exposing apps externally with Ingress. You’ll learn what Services are, how Ingress fits in, and how traffic flows through a Kubernetes cluster.
Kubernetes is a powerful platform for deploying microservices, but networking inside a cluster can be one of the most confusing aspects for developers and operators. Unlike traditional infrastructure, where IPs and ports are relatively fixed, Kubernetes introduces dynamic networking models, layered abstractions, and declarative routing.
Understanding the key building blocks - services, Ingress, and cluster networking - is critical to managing production-grade applications. Whether you’re debugging connectivity issues or building scalable APIs, you’ll need to know how traffic flows through your cluster and how different objects interact.
Kubernetes Networking 101: The Pod Network
The pod network is the foundation of all Kubernetes networking. Every pod in a Kubernetes cluster gets its own IP address, and all containers within the pod share that network namespace.
Kubernetes assumes a flat network where every pod can communicate with every other pod, regardless of which node it's on. This is enabled by the Container Network Interface (CNI), which varies by implementation (e.g., Calico, Cilium, Flannel).
However, pod IPs are ephemeral. When a pod is recreated (due to scaling, crashing, or rolling updates), it gets a new IP. That’s why relying on pod IPs for communication isn’t sustainable. This leads us to Kubernetes Services.
What Are Kubernetes Services?
A Service is a stable abstraction that provides reliable access to a group of pods. It defines a policy for accessing them, typically using label selectors to match the pods dynamically.
Services solve two big problems:
- Stable Networking – Even if pod IPs change, the service keeps a constant virtual IP (ClusterIP).
- Load Balancing – Services distribute traffic across all healthy pods behind them.
There are several types of Kubernetes Services, each with different purposes and exposure levels:
ClusterIP:
Default type. Exposes the service on an internal IP. Only accessible within the cluster.
NodePort:
Maps a port on every node to the service, enabling external traffic to reach it using <NodeIP>:<NodePort>.
LoadBalancer:
Provisions a cloud provider-managed load balancer that forwards traffic to the service.
ExternalName:
Maps the service to a DNS name outside the cluster.
By abstracting away pod details, Services ensure internal communication remains stable, reliable, and decoupled from container lifecycles.
When Services Aren’t Enough: Enter Ingress
Services are great for exposing applications inside the cluster, or even outside using NodePort or LoadBalancer, but they’re not ideal for managing HTTP routing or exposing multiple services via a single entry point.
That’s where Ingress comes in.
An Ingress is a Kubernetes resource that defines HTTP(S) routing rules. It lets you route external traffic to different services based on hostnames or URL paths. This provides fine-grained control over your application’s entry points and enables advanced routing strategies.
For example:
rules:
- host: api.example.com
http:
paths:
- path: /users
pathType: Prefix
backend:
service:
name: user-service
port:
number: 80
- path: /orders
pathType: Prefix
backend:
service:
name: order-service
port:
number: 80
With a single domain (api.example.com), traffic can be routed to different microservices seamlessly.
How Ingress Works: Controllers and Load Balancers
An Ingress resource does nothing on its own. You need an Ingress Controller—a specialized pod or service that watches Ingress definitions and configures a proxy (like NGINX, Traefik, or HAProxy) accordingly.
When using a cloud provider, the ingress controller typically works in tandem with a LoadBalancer service to expose itself to the outside world.
Here’s how it all fits together:
- An external user makes a request to api.example.com.
- DNS resolves the domain to the external IP of a LoadBalancer.
- The request hits the Ingress Controller.
- The controller inspects the Ingress rules and forwards the request to the appropriate backend service.
- The service routes traffic to the correct pod.
Ingress consolidates traffic management, supports TLS termination, and offers clean URLs, without requiring each service to manage its own external exposure.
Kubernetes Networking Flow: A Real Example
Let’s say you’ve deployed a frontend, a backend API, and a metrics dashboard in a Kubernetes cluster. You want them available at:
- myapp.com → Frontend
- myapp.com/api → Backend
- myapp.com/metrics → Dashboard
Here’s how you might wire this up:
- Each app has its own deployment and service (type: ClusterIP).
- You deploy an Ingress Controller (e.g., NGINX).
- You define an Ingress resource with three path-based rules.
- A LoadBalancer service exposes the Ingress Controller to the internet.
Now, your apps are reachable through clean, routeable URLs—no need to expose each app individually.
Common Pitfalls and Misunderstandings
Despite its power, Kubernetes networking can be frustrating. Some common issues include:
Assuming pod IPs are static: They’re not. Always use services or DNS.
Forgetting to install an Ingress Controller: The Ingress resource won’t work unless a controller is running.
Overusing NodePort: While simple, NodePort doesn’t scale well and exposes each node publicly, which may violate security best practices.
Neglecting TLS and HTTPS routing: Ingress supports TLS termination, but it must be configured correctly—often involving cert-manager or manual secret management.
Confusing ClusterIP vs. LoadBalancer: ClusterIP is internal only. LoadBalancer is cloud-specific and provisions external access.
Understanding how these pieces work together prevents outages and unlocks scalable, secure traffic management.
How Platform Teams Simplify Ingress and Networking
In modern cloud-native teams, platform engineers often take ownership of networking complexity. Instead of asking developers to write Ingress rules or manage certificates, they provide abstractions through Internal Developer Portals (IDPs).
These portals allow developers to:
- Request routes through a UI or CLI
- Deploy services behind pre-configured ingress controllers
- Automatically enforce TLS and DNS policies
This accelerates development while ensuring compliance, consistency, and observability across environments.
In Summary
Kubernetes networking relies on a layered model of pods, services, and ingress to route traffic within and into the cluster. Services abstract away pod volatility, while Ingress enables scalable and maintainable HTTP routing.
To build resilient systems, teams must understand how these components interact and when to use each. Whether you’re deploying APIs, dashboards, or full web apps, mastering services and ingress is essential to exposing workloads securely and reliably.
At Harness, we believe developers shouldn't have to worry about this complexity. Our Internal Developer Portal can provide a seamless way to manage routes, ingress, TLS, and traffic flows, without writing YAML or debugging proxy configs.
FAQ: Understanding Kubernetes Services, Ingress, and Networking
What is a Kubernetes Service?
A Service is an abstraction that routes traffic to a group of pods. It ensures stability and load balancing even as pod IPs change.
What is Ingress in Kubernetes?
Ingress is a Kubernetes resource that defines HTTP routing rules for exposing services externally using clean URLs and domain names.
How does traffic flow into a Kubernetes cluster?
External traffic typically enters via a LoadBalancer, hits an Ingress Controller, and is routed to the appropriate service and pod.
Can you access a pod directly in Kubernetes?
Direct access to pods is discouraged. Instead, traffic should go through Services or Ingress for stability and security.
What’s the difference between ClusterIP, NodePort, and LoadBalancer?
- ClusterIP: Internal-only access
- NodePort: Exposes service via a node’s IP and port
- LoadBalancer: Provides a cloud-managed external IP