Table of Contents
Description
On this example, a new Istio Ingress Load Balancer is deployed through the usage of an IstioOperator object, as well deploys a simple service for testing purposes.
This example configures:
Generic Kubernetes resources:
- 1 Service
- 1 Deployment
Istio resources:
- 1 Ingress Gateway Load Balancer
- 1 Gateway
- 1 Virtual Service
Note:
I don't intend to explain thing related to Kubernetes unless necessary.
Configuration
Namespace
Creates the namespace istio-ingress with the istio-injection enabled.
apiVersion: v1
kind: Namespace
metadata:
name: istio-ingress
labels:
istio-injection: "enabled"
Service
Creates a service named helloworld.
This service listens for the port 80 expecting HTTP traffic and will forward the incoming traffic towards the port 80 from the destination pod.
apiVersion: v1
kind: Service
metadata:
name: helloworld
labels:
app: helloworld
service: helloworld
spec:
ports:
- port: 80
name: http
selector:
app: helloworld
Deployment
Deploys a Nginx server that listens for the port 80.
apiVersion: apps/v1
kind: Deployment
metadata:
name: helloworld-nginx
labels:
app: helloworld
spec:
replicas: 1
selector:
matchLabels:
app: helloworld
template:
metadata:
labels:
app: helloworld
spec:
containers:
- name: helloworld
image: nginx
resources:
requests:
cpu: "100m"
imagePullPolicy: IfNotPresent #Always
ports:
- containerPort: 80
IstioOperator
Deploys an Istio Ingress Load Balancer named myistio-ingressgateway.
It will contain the selector istio: myingressgateway.
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
name: ingress
spec:
profile: empty # Do not install CRDs or the control plane
components:
ingressGateways:
- name: myistio-ingressgateway
namespace: istio-ingress
enabled: true
label:
# Set a unique label for the gateway. This is required to ensure Gateways
# can select this workload
istio: myingressgateway
values:
gateways:
istio-ingressgateway:
# Enable gateway injection
injectionTemplate: gateway
Gateway
Deploys an Istio gateway that's listening to the port 80 for HTTP traffic.
It doesn't filter for any specific host.
The selector field is used to "choose" which Istio Load Balancers will have this gateway assigned to.
On this scenario, we want to target the Istio Ingress Load Balancer we just created, therefore the value of the selector will be istio: myingressgateway.
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: helloworld-gateway
spec:
selector:
istio: myingressgateway # Uses the selector we just deployed
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "*"
VirtualService
The Virtual Service resources are used to route and filter the received traffic from the gateway resources, and route it towards the desired destination.
On this example we select the gateway helloworld-gateway, which is the gateway that 's described in the Gateway section.
On this resource, we are also not limiting the incoming traffic to any specific host, allowing for all the incoming traffic to go through the rules set.
Here we created a rule that will be applied on HTTP related traffic (including HTTPS and HTTP2) when the destination path is exactly /helloworld.
This traffic will be forwarded to the port 80 of the destination service helloworld (the full path URL equivalent would be helloworld.$NAMESPACE.svc.cluster.local).
Additionally, there will be an internal URL rewrite set, as if the URL is not modified, it would attempt to reach to the /helloworld path from the Nginx deployment, which currently has no content and would result in an error code 404 (Not found).
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld-vs
spec:
hosts:
- "*"
gateways:
- helloworld-gateway
http:
- match:
- uri:
exact: /helloworld
route:
- destination:
host: helloworld
port:
number: 80
rewrite:
uri: "/"
Walkthrough
Deploy resources
Deploy the resources.
kubectl apply -f ./
namespace/istio-ingress created
deployment.apps/helloworld-nginx created
gateway.networking.istio.io/helloworld-gateway created
service/helloworld created
Wait for the deployment to be ready
Wait for the Nginx deployment to be up and ready.
kubectl get deployment helloworld-nginx -w
NAME READY UP-TO-DATE AVAILABLE AGE
helloworld-nginx 1/1 1 1 16s
Install the Istio Ingress Gateway Load Balancer
istioctl install -f IstioOperator/IstioOperator.yaml -y
✔ Ingress gateways installed
✔ Installation complete
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Test the service
Get LB IP
To perform the desired tests, we will need to obtain the IP Istio Load Balancer that we selected in the Gateway section.
On my environment, the IP is the 192.168.1.50.
kubectl get svc -l istio=myingressgateway -A
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
istio-ingress myistio-ingressgateway LoadBalancer 10.96.116.25 192.168.1.51 15021:31681/TCP,80:31993/TCP,443:32596/TCP 116s
Curl /helloworld
Due to accessing the path /helloworld, we are triggering the rule set on the VirtualService configuration, sending a request to the Nginx backend and returning us its contents.
curl 192.168.1.51/helloworld -s | grep "<title>.*</title>"
<title>Welcome to nginx!</title>
Curl /other
What happens if we access a path or URL that doesn't trigger any rule?
curl 192.168.1.51/other -s -I
HTTP/1.1 404 Not Found
date: Sat, 01 Jul 2023 13:27:14 GMT
server: istio-envoy
transfer-encoding: chunked
We receive a status code 404.
I would like to put emphasis on the following line returned:
server: istio-envoy
This means that the contents returned was performed by the Istio service, therefore, the request was able to reach Istio and received a response from it.
Cleanup
Finally, a cleanup from the resources deployed.
It might take a minute or two, don't panik if that's the case.
Take into account that deleting the namespace will also delete the resources in it, so be careful!
kubectl delete -f ./
namespace "istio-ingress" deleted
deployment.apps "helloworld-nginx" deleted
gateway.networking.istio.io "helloworld-gateway" deleted
service "helloworld" deleted
virtualservice.networking.istio.io "helloworld-vs" deleted