02-DirectResponse-HTTP-Body documented
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https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPDirectResponse
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https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPBody
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---
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gitea: none
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include_toc: true
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---
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# Description
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Based on the [previous example](../../01-Getting_Started/01-hello_world_1_service_1_deployment), we configure the [VirtualService](#virtualservice) to return a specific response to the client with the contents of our choice.
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This example configures:
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Generic Kubernetes resources:
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- 1 Service
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- 1 Deployments
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Istio resources:
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- 1 Gateway
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- 1 Virtual Service
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# Continues from
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# Based on
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- 01-hello_world_1_service_1_deployment
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- [01-hello_world_1_service_1_deployment](../../01-Getting_Started/01-hello_world_1_service_1_deployment)
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# Configuration
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## Service
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Creates a service named `helloworld`.
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This service listens for the port `80` expecting `HTTP` traffic and will forward the incoming traffic towards the port `80` from the destination pod.
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: helloworld
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labels:
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app: helloworld
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service: helloworld
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spec:
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ports:
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- port: 80
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name: http
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selector:
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app: helloworld
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```
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## Deployment
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Deploys a Nginx server that listens for the port `80`.
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: helloworld-nginx
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labels:
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app: helloworld
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spec:
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replicas: 1
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selector:
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matchLabels:
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app: helloworld
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template:
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metadata:
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labels:
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app: helloworld
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spec:
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containers:
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- name: helloworld
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image: nginx
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resources:
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requests:
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cpu: "100m"
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imagePullPolicy: IfNotPresent #Always
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ports:
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- containerPort: 80
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```
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## Gateway
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Deploys an Istio gateway that's listening to the port `80` for `HTTP` traffic.
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It doesn't filter for any specific host.
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The `selector` field is used to "choose" which Istio Load Balancers will have this gateway assigned to.
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The Istio `default` profile creates a Load Balancer in the namespace `istio-system` that has the label `istio: ingressgateway` set, allowing us to target that specific Load Balancer and assign this gateway resource to it.
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```yaml
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apiVersion: networking.istio.io/v1alpha3
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kind: Gateway
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metadata:
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name: helloworld-gateway
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spec:
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selector:
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istio: ingressgateway # use istio default controller
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servers:
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- port:
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number: 80
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name: http
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protocol: HTTP
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hosts:
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- "*"
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```
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## VirtualService
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The configuration set, targets the [gateway created](#gateway) as well of not limiting the traffic to any specific host.
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We configure 2 rules for HTTP traffic (this includes `HTTPS` and `HTTP2`, this will be my last warning about this).
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The first rule configure will match when the requested path is `/helloworld`.
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This traffic will be forwarded to the service `helloworld.default.svc.cluster.local` with port `80`.
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The second rule, which will manage the rest of the traffic, will return a response with status code `404`, and body content set to `Page Not Found`.
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Additionally, for consistency and good practices purposes, we also specified the content type of the page to `text/plain`.
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```yaml
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apiVersion: networking.istio.io/v1beta1
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kind: VirtualService
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metadata:
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name: helloworld-vs
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spec:
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hosts:
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- "*"
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gateways:
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- helloworld-gateway
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http:
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- name: helloworld
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match:
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- uri:
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exact: /helloworld
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route:
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- destination:
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host: helloworld.default.svc.cluster.local
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port:
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number: 80
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rewrite:
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uri: "/"
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- name: default
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directResponse:
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status: 404
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body:
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string: "Page Not Found"
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headers:
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response:
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set:
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content-type: "text/plain"
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```
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# Walkthrough
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## Deploy resources
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Deploy the resources.
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```shell
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kubectl apply -f ./
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```
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```text
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deployment.apps/helloworld-nginx created
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gateway.networking.istio.io/helloworld-gateway created
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service/helloworld created
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virtualservice.networking.istio.io/helloworld-vs created
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```
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## Wait for the pods to be ready
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Wait for the Apache and Nginx deployments to be up and ready.
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```shell
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kubectl get deployment helloworld-nginx -w
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```
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```text
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NAME READY UP-TO-DATE AVAILABLE AGE
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helloworld-v1 1/1 1 1 4m1s
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helloworld-v2 1/1 1 1 4m1s
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```
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## Test the service
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### Get LB IP
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To perform the desired tests, we will need to obtain the IP Istio Load Balancer that we selected in the [Gateway section](#gateway).
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On my environment, the IP is the `192.168.1.50`.
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```shell
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kubectl get svc -l istio=ingressgateway -A
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```
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```text
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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istio-ingressgateway LoadBalancer 10.97.47.216 192.168.1.50 15021:31316/TCP,80:32012/TCP,443:32486/TCP 39h
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```
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### helloworld
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As expected, we receive the contents from the Nginx contents
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```shell
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curl 192.168.1.50/helloworld -s | grep "<h1>.*</h1>"
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```
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```text
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<h1>Welcome to nginx!</h1>
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```
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### other paths
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#### /
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We receive the contents "Page Not Found".
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```shell
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curl 192.168.1.50/
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```
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```text
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Page Not Found
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```
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Checking the headers, we also can see the status code is set to `404`, as well of the content-type we specified on the [VirtualService configuration](#virtualservice).
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```shell
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curl 192.168.1.50/ -I
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```
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```text
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HTTP/1.1 404 Not Found
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content-type: text/plain
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content-length: 14
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date: Thu, 04 May 2023 01:18:50 GMT
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server: istio-envoy
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```
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#### /found
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We can confirm that this behavior applies to other paths (as it is matching the "default" rule we set in [VirtualService configuration]).
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```shell
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curl 192.168.1.50/found
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```
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```text
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Page Not Found
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```
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```shell
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curl 192.168.1.50/found -I
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```
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```text
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HTTP/1.1 404 Not Found
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content-type: text/plain
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content-length: 14
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date: Thu, 04 May 2023 01:20:40 GMT
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server: istio-envoy
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```
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## Cleanup
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Finally, a cleanup from the resources deployed.
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```shell
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kubectl delete -f ./
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```
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```text
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deployment.apps "helloworld-nginx" deleted
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gateway.networking.istio.io "helloworld-gateway" deleted
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service "helloworld" deleted
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virtualservice.networking.istio.io "helloworld-vs" deleted
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```
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# Links of interest
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- https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPDirectResponse
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- https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPBody
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@ -10,5 +10,4 @@ spec:
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- port: 80
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name: http
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selector:
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app: helloworld
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---
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app: helloworld
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@ -1,4 +1,3 @@
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---
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apiVersion: networking.istio.io/v1beta1
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kind: VirtualService
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metadata:
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@ -15,7 +14,7 @@ spec:
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exact: /helloworld
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route:
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- destination:
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host: helloworld
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host: helloworld.default.svc.cluster.local
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port:
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number: 80
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rewrite:
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