Ingresses Path Matching Using Path-Regex Annotation

How to customize Ingress and Mergeable Ingress types with path-regex annotations.

Customizing NGINX Ingress Controller with Path-Regex Annotations

We suggest reading the NGINX documentation on resolve location priority to gain additional context about NGINX and NGINX Plus before using the path-regex annotation.

Ingress Type

In this example, you will use the nginx.org/path-regex annotations to add regex modifiers to the location paths.

Start by modifying cafe-ingress.yaml metadata to add the annotation section and configure the nginx.org/path-regex annotation.

cafe-ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress
  annotations:
    nginx.org/path-regex: "case_sensitive"
spec:
  tls:
  - hosts:
    - cafe.example.com
    secretName: cafe-secret
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea/[A-Z0-9]
        backend:
          serviceName: tea-svc
          servicePort: 80
      - path: /coffee/[A-Z0-9]
        backend:
          serviceName: coffee-svc
          servicePort: 80

After creating the Ingress (kubectl create -f cafe-ingres.yaml), all defined paths will be updated. In the generated NGINX config file the tea and coffee paths will look like in the snippets below:

tea path:

location ~ "^/tea/[A-Z0-9]"

coffee path:

location ~ "^/coffee/[A-Z0-9]"

Note that the regex modifier case_sensitive is applied to all paths.

To change regex modifier value from case_sensitive to case_insensitive update the nginx.org/path-regex annotation.

The config cafe-ingress.yaml file below shows the change.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress
  annotations:
    nginx.org/path-regex: "case_insensitive"
spec:
  tls:
  - hosts:
    - cafe.example.com
    secretName: cafe-secret
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea/[A-Z0-9]
        backend:
          serviceName: tea-svc
          servicePort: 80
      - path: /coffee/[A-Z0-9]
        backend:
          serviceName: coffee-svc
          servicePort: 80

In the NGINX config file, the /tea/[A-Z0-9] and /coffee/[A-Z0-9] paths should look like in the snippets below.

tea path

location ~* "^/tea/[A-Z0-9]"

coffee path

location ~* "^/coffee/[A-Z0-9]"

Mergeable Ingress Type

This document section explains how to deploy and configure Mergeable Ingress Type.

First, you will deploy a Master Ingress and two Minion Ingresses. Then, you will configure them with path-regex annotations.

Create a Master Ingress.

cafe-master.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-master
  annotations:
    nginx.org/mergeable-ingress-type: "master"
spec:
  ingressClassName: nginx
  tls:
  - hosts:
    - cafe.example.com
    secretName: cafe-secret
  rules:
  - host: cafe.example.com

Create the Ingress

kubectl create -f cafe-master.yaml

Verify the Master Ingress was created

kubectl get ingress cafe-ingress-master

NAME                  CLASS   HOSTS              ADDRESS   PORTS     AGE
cafe-ingress-master   nginx   cafe.example.com             80, 443   29s

kubectl describe ingress cafe-ingress-master

Name:             cafe-ingress-master
Labels:           <none>
Namespace:        default
Address:
Ingress Class:    nginx
Default backend:  <default>
TLS:
  cafe-secret terminates cafe.example.com
Rules:
  Host        Path  Backends
  ----        ----  --------
  *           *     <default>
Annotations:  nginx.org/mergeable-ingress-type: master
Events:
  Type    Reason          Age   From                      Message
  ----    ------          ----  ----                      -------
  Normal  AddedOrUpdated  62s   nginx-ingress-controller  Configuration for default/cafe-ingress-master was added or updated

Create the first Ingress Minion.

tea-minion.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-tea-minion
  annotations:
    nginx.org/mergeable-ingress-type: "minion"
spec:
  ingressClassName: nginx
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea
        pathType: Prefix
        backend:
          service:
            name: tea-svc
            port:
              number: 80

kubectl create -f tea-minion.yaml

ingress.networking.k8s.io/cafe-ingress-tea-minion created

Verify the Minion was created:

kubectl get ingress cafe-ingress-tea-minion

NAME                      CLASS   HOSTS              ADDRESS   PORTS   AGE
cafe-ingress-tea-minion   nginx   cafe.example.com             80      23m

kubectl describe ingress cafe-ingress-tea-minion

Name:             cafe-ingress-tea-minion
Labels:           <none>
Namespace:        default
Address:
Ingress Class:    nginx
Default backend:  <default>
Rules:
  Host              Path  Backends
  ----              ----  --------
  cafe.example.com
                    /tea   tea-svc:80 (10.244.0.6:8080,10.244.0.7:8080,10.244.0.8:8080)
Annotations:        nginx.org/mergeable-ingress-type: minion
Events:
  Type    Reason          Age   From                      Message
  ----    ------          ----  ----                      -------
  Normal  AddedOrUpdated  24m   nginx-ingress-controller  Configuration for default/cafe-ingress-tea-minion was added or updated

Create the second Ingress Minion.

tea-minion.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-tea-minion
  annotations:
    nginx.org/mergeable-ingress-type: "minion"
spec:
  ingressClassName: nginx
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea
        pathType: Prefix
        backend:
          service:
            name: tea-svc
            port:
              number: 80

kubectl create -f tea-minion.yaml

ingress.networking.k8s.io/cafe-ingress-tea-minion created

Verify the Minion Ingress was created:

kubectl get ingress cafe-ingress-tea-minion

NAME                      CLASS   HOSTS              ADDRESS   PORTS   AGE
cafe-ingress-tea-minion   nginx   cafe.example.com             80      5m21s

kubectl describe ingress cafe-ingress-tea-minion

Name:             cafe-ingress-tea-minion
Labels:           <none>
Namespace:        default
Address:
Ingress Class:    nginx
Default backend:  <default>
Rules:
  Host              Path  Backends
  ----              ----  --------
  cafe.example.com
                    /tea   tea-svc:80 (10.244.0.6:8080,10.244.0.7:8080,10.244.0.8:8080)
Annotations:        nginx.org/mergeable-ingress-type: minion
Events:
  Type    Reason          Age    From                      Message
  ----    ------          ----   ----                      -------
  Normal  AddedOrUpdated  5m52s  nginx-ingress-controller  Configuration for default/cafe-ingress-tea-minion was added or updated

You created a Master Ingress and two Minion Ingresses. Minion Ingresses are defined with two paths: /tea and /coffee.

In the following steps, you will modify the paths by applying regex modifiers.

Update the Minion Ingress Tea:

add path-regex annotation with value case_insensitive
modify path with regex you want to use (in the example below: /tea/[A-Z0-9])

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-tea-minion
  annotations:
    nginx.org/mergeable-ingress-type: "minion"
    nginx.org/path-regex: "case_insensitive"
spec:
  ingressClassName: nginx
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /tea/[A-Z0-9]
        pathType: Prefix
        backend:
          service:
            name: tea-svc
            port:
              number: 80

Apply the changes:

kubectl apply -f tea-minion.yaml

Verify the change:

kubectl describe ingress cafe-ingress-tea-minion

Name:             cafe-ingress-tea-minion
Labels:           <none>
Namespace:        default
Address:
Ingress Class:    nginx
Default backend:  <default>
Rules:
  Host              Path  Backends
  ----              ----  --------
  cafe.example.com
                    /tea/[A-Z0-9]   tea-svc:80 (10.244.0.6:8080,10.244.0.7:8080,10.244.0.8:8080)
Annotations:        nginx.org/mergeable-ingress-type: minion
                    nginx.org/path-regex: case_insensitive
Events:
  Type    Reason          Age                From                      Message
  ----    ------          ----               ----                      -------
  Normal  AddedOrUpdated  47s (x2 over 34m)  nginx-ingress-controller  Configuration for default/cafe-ingress-tea-minion was added or updated

Looking at the updated list of annotations, we can see the new path-regex annotation was added.

It updates the path /tea/[A-Z0-9] using the case_insensitive regex modifier. Updated path (location) in the NGINX config file: location ~* "^/tea/[A-Z0-9]".

Note that the path-regex annotation applies only to paths defined on the corresponding Minion Ingress. The paths defined in the second Minion (coffee) are not modified.

Follow the steps below to configure the type case_sensitive regex modifier on the Second Minion Ingress.

Modify deployed coffee-minion.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-coffee-minion
  annotations:
    nginx.org/mergeable-ingress-type: "minion"
spec:
  ingressClassName: nginx
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /coffee
        pathType: Prefix
        backend:
          service:
            name: coffee-svc
            port:
              number: 80

Add path-regex annotation and modify the path /coffee:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: cafe-ingress-coffee-minion
  annotations:
    nginx.org/mergeable-ingress-type: "minion"
    nginx.org/path-regex: "case_sensitive"
spec:
  ingressClassName: nginx
  rules:
  - host: cafe.example.com
    http:
      paths:
      - path: /coffee/[A-Za-z0-9]
        pathType: Prefix
        backend:
          service:
            name: coffee-svc
            port:
              number: 80

Apply changes to the Minion Ingress:

kubectl apply -f coffee-minion.yaml

ingress.networking.k8s.io/cafe-ingress-coffee-minion created

Verify the applied changes:

kubectl describe ingress cafe-ingress-coffee-minion

Name:             cafe-ingress-coffee-minion
Labels:           <none>
Namespace:        default
Address:
Ingress Class:    nginx
Default backend:  <default>
Rules:
  Host              Path  Backends
  ----              ----  --------
  cafe.example.com
                    /coffee/[A-Za-z0-9]   coffee-svc:80 (10.244.0.10:8080,10.244.0.9:8080)
Annotations:        nginx.org/mergeable-ingress-type: minion
                    nginx.org/path-regex: case_sensitive
Events:
  Type    Reason          Age   From                      Message
  ----    ------          ----  ----                      -------
  Normal  AddedOrUpdated  11m   nginx-ingress-controller  Configuration for default/cafe-ingress-coffee-minion was added or updated

The new annotation nginx.org/path-regex was added. It updates the path /coffee/[A-Za-z0-9] using the case_sensitive regex modifier. Updated path (location) in the NGINX config file: location ~ "^/coffee/[A-Za-z0-9]".