kubernetes: access Ingress within a Pod - kubernetes

Question

I have an Ingress object set up to route traffic to the appropriate Service based on the Url path. I would like to access/expose this Ingress object within another Pod. I'm wondering if this is possible?
I tried to set up a Service on the Ingress but that didn't seem to work.

Answer 1

So, for whatever reason (ssr, lots of microservices, etc) you want to access k8s resources using their ingress path mapping, instead of calling each service by its internal name.
For example, you have an ingress config like that:
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: ingress-service
annotations:
kubernetes.io/ingress.class: nginx
nginx.ingress.kubernetes.io/use-regex: 'true'
spec:
rules:
- host: example.com
http:
paths:
- path: /api/users/?(.*)
backend:
serviceName: auth-service
servicePort: 80
- path: /api/cart/?(.*)
backend:
serviceName: cart-service
servicePort: 80
and you want to access auth-service using http://example.com/api/auth instead of http://auth-service.
All you have to do is replace domain part (example.com in our case) with ingress service url. It depends on your configuration and environment, but usually it looks like http://[SERVICE_NAME].[NAMESPACE], for example:
GCP - http://ingress-nginx-controller.ingress-nginx
Helm ingress nginx - http://my-release-ingress-nginx-controller (here we are
using only service name part, because helm installs ingress in
default namespace)
Minikube - if you are using minikube ingress
addon, then you might run into problem where you cannot access
ingress, then just use helm version. (dont disable ingress addon - just install helm version alongside of it)
Get namespaces: kubectl get namespaces
Get service names inside namespace kubectl get services -n [NAMESPACE].

Answer 2

If you have assigned a host name, you also have to provide the domain name and IP address of the cluster to the /etc/hosts file. When you access a service via Ingress from outside the cluster, this is the file that is consulted for host name resolution.
However, a pod running inside a cluster does not have access to this /etc/hosts file. It has its own /etc/hosts file. To use ingress, the pod needs to have the same domain name and IP address entry in it's own /etc/hosts file.
To achieve this, you have to use hostAliases. Here's a sample of how that works:
apiVersion: v1
kind: Pod
metadata:
...
spec:
hostAliases:
- ip:<IP address>
hostnames:
- <host name>
For more detail on hostAliases, go to this link

Answer 3

I have spend so much time on this issue. I found very simple solution. I am using Mac Docker Desktop 3.3.1.
My Kubernetes Version: 1.19.7
I am trying to access UI URL from another pod running in the cluster.
My UI Service
apiVersion: v1
kind: Service
metadata:
name: my-ui-service
spec:
type: LoadBalancer
selector:
app: my-ui
ports:
- protocol: TCP
port: 8080
targetPort: 8080
Ingress for the service
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: my-ingress
spec:
rules:
- host: my-site.com
http:
paths:
- pathType: Prefix
path: /
backend:
service:
name: my-ui-service
port:
number: 8080
I have used NGINX Ingress Controller.
Command to run the Ingress Controller:
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.48.1/deploy/static/provider/cloud/deploy.yaml
Once the controller is ready run the command to see the status of ingress.
kubectl get ingress
Now see the description of the ingress:
kubectl describe ingress my-ingress
Here you will find
Rules:
Host Path Backends
---- ---- --------
my-site.com
/ my-ui-service:8080 (10.1.2.198:8080)
In any pod in the cluster you can access the domain my-site.com by using my-ui-service:8080.

Answer 4

Inside your cluster your pods use services to reach other pods.
From outside the cluster a client may use ingress to reach services.
Ingress resource allows connection to services.
So your pod need to be reachable by a service (my-svc-N in the following example), which you're going to use in your ingress definition.
Take a look at this example:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: example-ing
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
backend:
serviceName: default-http-backend
servicePort: 80
rules:
- host: my-kube.info
http:
paths:
- path: /
backend:
serviceName: my-svc-1
servicePort: 80
- host: cheeses.all
http:
paths:
- path: /aaa
backend:
serviceName: my-svc-2
servicePort: 80
- path: /bbb
backend:
serviceName: my-svc-3
servicePort: 80