Ingress annotations for customization in Kubernetes - Step-by-Step Execution

Process Flow - Ingress annotations for customization

Create Ingress resource

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Add annotations in metadata

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Ingress controller reads annotations

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Apply custom behavior (e.g., rewrite, timeout)

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Ingress routes traffic with customization

Annotations are added to the Ingress resource metadata to tell the Ingress controller how to customize traffic routing and behavior.

Execution Sample

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: "/"

This Ingress resource uses an annotation to rewrite the URL path to '/' before forwarding.

Process Table

Step	Action	Annotation Read	Effect on Ingress Controller	Resulting Behavior
1	Ingress resource created	nginx.ingress.kubernetes.io/rewrite-target: /	Controller detects rewrite annotation	URL paths rewritten to '/'
2	Ingress controller processes request	rewrite-target: /	Modifies request path	Request forwarded with rewritten path
3	Ingress controller applies default rules	No conflicting annotations	Default routing applies	Traffic routed to backend service
4	No more annotations	End of annotation list	No further customization	Ingress routing complete

💡 All annotations processed; Ingress controller applies customizations and routes traffic accordingly

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
Ingress Annotations	{}	{"nginx.ingress.kubernetes.io/rewrite-target": "/"}	{"nginx.ingress.kubernetes.io/rewrite-target": "/"}	{"nginx.ingress.kubernetes.io/rewrite-target": "/"}	{"nginx.ingress.kubernetes.io/rewrite-target": "/"}
Request Path	/app	/app	/	/	/
Routing Decision	None	None	Rewrite applied	Route to backend	Route complete

Key Moments - 3 Insights

Why does the request path change from '/app' to '/'?

Because the annotation 'nginx.ingress.kubernetes.io/rewrite-target: /' tells the Ingress controller to rewrite the path before forwarding, as shown in execution_table step 2.

What happens if there are no annotations in the Ingress resource?

The Ingress controller applies default routing rules without customization, as seen in execution_table step 3.

Can multiple annotations be processed at once?

Yes, the controller reads all annotations in metadata and applies their effects in order, but this example shows a single annotation for clarity.

Visual Quiz - 3 Questions

Look at the execution table, what is the request path after step 2?

A "/app"

B "/"

C "/rewrite"

D "/backend"

💡 Hint

Check the 'Request Path' variable in variable_tracker after Step 2.

At which step does the Ingress controller apply default routing rules?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Look at the 'Effect on Ingress Controller' column in execution_table for default routing.

If the annotation 'nginx.ingress.kubernetes.io/rewrite-target' was removed, what would happen to the request path?

A It would be blocked

B It would be rewritten to '/'

C It would remain unchanged as '/app'

D It would be redirected to another domain

💡 Hint

Refer to key_moments about behavior without annotations and variable_tracker initial values.

Concept Snapshot

Ingress annotations customize traffic routing by adding key-value pairs in metadata.
Annotations tell the Ingress controller how to modify requests (e.g., rewrite paths).
The controller reads annotations and applies changes before routing.
Without annotations, default routing rules apply.
Annotations enable flexible, per-Ingress customization without changing backend services.

Full Transcript

Ingress annotations are special settings added to the metadata of an Ingress resource in Kubernetes. When you create an Ingress, you can add annotations as key-value pairs. The Ingress controller reads these annotations and changes how it handles incoming traffic. For example, the annotation 'nginx.ingress.kubernetes.io/rewrite-target: /' tells the controller to change the request path to '/' before sending it to the backend service. This lets you customize routing without changing your backend apps. If no annotations are present, the controller just routes traffic normally. This visual trace shows how the controller reads annotations step-by-step, applies changes like rewriting paths, and then routes the traffic accordingly.