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02-Target_Namespace documented

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03-Gateway_Ingress/02-Target_Namespace/01-namespace.yaml Executable file
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apiVersion: v1
kind: Namespace
metadata:
name: foo

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03-Gateway_Ingress/02-Target_Namespace/Deployment.yaml Executable file
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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

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03-Gateway_Ingress/02-Target_Namespace/Gateway.yaml Normal file
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apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: helloworld-gateway
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 80
name: http-b
protocol: HTTP
hosts:
- "foo/*"

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03-Gateway_Ingress/02-Target_Namespace/README.md Executable file
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---
gitea: none
include_toc: true
---
# Description
This example deploys the same infrastructure as the [previous example](../../01-Getting_Started/01-hello_world_1_service_1_deployment), and restrict which `VirtualService` Istio resources can access/select the `Gateway` Istio resource, based on the `VirtualService` namespace.
The domain host targeted will be `my.domain`.
This example configures:
Generic Kubernetes resources:
- 1 Service
- 1 Deployment
- 1 Namespace
Istio resources (`default` namespace):
- 1 Gateway
- Virtual Service
Istio resources (`foo`namespace):
- 1 Virtual Service
> **Note:**\
> I don't intend to explain thing related to Kubernetes unless necessary.
# Based on
- [01-hello_world_1_service_1_deployment](../../01-Getting_Started/01-hello_world_1_service_1_deployment
# Configuration
## 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.
```yaml
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`.
```yaml
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
```
## Namespace
Creates a namespace named `foo`.
```yaml
apiVersion: v1
kind: Namespace
metadata:
name: foo
```
## Gateway
Deploys an Istio gateway that's listening to the port `80` for `HTTP` traffic.
The gateway won't target any specific host domain, yet limits the `VirtualService` Istio resources that can target this gateway, limiting its access to the `VirtualServices` Istio resources created in the `foo` namespace.
The `selector` field is used to "choose" which Istio Load Balancers will have this gateway assigned to.
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.
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: helloworld-gateway
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 80
name: http-b
protocol: HTTP
hosts:
- "foo/*"
```
## VirtualService
We will create two `VirtualServices` with the same configuration, only difference will be the namespace they are created onto (and the destination path), this will be used to test if the [`Gateway` namespace restriction configured](#gateway) is being applied to the `VirtualService` resources as desired.
On this example we select the gateway `helloworld-gateway`, which is the [gateway that 's described in the `Gateway` section](#gateway).
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.
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).
## helloworld-foo
`VirtualService` created in the namespace `foo`.
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.default.svc.cluster.local`.
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld-foo
namespace: foo
spec:
hosts:
- "*"
gateways:
- default/helloworld-gateway
http:
- match:
- uri:
exact: /helloworld
route:
- destination:
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite:
uri: "/"
```
## helloworld-default
`VirtualService` created in the namespace `default`.
Here we created a rule that will be applied on `HTTP` related traffic (including `HTTPS` and `HTTP2`) when the destination path is exactly `/failure`.
This traffic will be forwarded to the port `80` of the destination service `helloworld.default.svc.cluster.local`.
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld-default
namespace: default
spec:
hosts:
- "*"
gateways:
- default/helloworld-gateway
http:
- match:
- uri:
exact: /failure
route:
- destination:
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite:
uri: "/"
```
# Walkthrough
## Deploy resources
Deploy the resources.
```shell
kubectl apply -f ./
```
```text
namespace/foo created
deployment.apps/helloworld-nginx created
gateway.networking.istio.io/helloworld-gateway created
service/helloworld created
virtualservice.networking.istio.io/helloworld-foo created
virtualservice.networking.istio.io/helloworld-default created
```
## Wait for the deployment to be ready
Wait for the Nginx deployment to be up and ready.
```shell
kubectl get deployment helloworld-nginx -w
```
```text
NAME READY UP-TO-DATE AVAILABLE AGE
helloworld-nginx 1/1 1 1 44s
```
## 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](#gateway).
On my environment, the IP is the `192.168.1.50`.
```shell
kubectl get svc -l istio=ingressgateway -A
```
```text
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
istio-ingressgateway LoadBalancer 10.97.47.216 192.168.1.50 15021:31316/TCP,80:32012/TCP,443:32486/TCP 39h
```
### Curl /helloworld
When performing a curl towards the destination path, as we are not using the domain host specified in the [gateway resource](#gateway), we are failing to match any rule.
```shell
curl 192.168.1.50/helloworld -I
```
```text
HTTP/1.1 404 Not Found
date: Wed, 10 May 2023 08:25:26 GMT
server: istio-envoy
transfer-encoding: chunked
```
### Curl my.domain/helloworld
We can "fake" the destination domain by modifying the `Host` header.
After setting that up, and attempting to curl the destination, we receive a positive response from the Nginx backend.
```shell
curl 192.168.1.50/helloworld -s -HHOST:my.domain | grep "<title>.*</title>"
```
```text
<title>Welcome to nginx!</title>
```
## Cleanup
Finally, a cleanup from the resources deployed.
```shell
kubectl delete -f ./
```
```text
namespace "foo" deleted
deployment.apps "helloworld-nginx" deleted
gateway.networking.istio.io "helloworld-gateway" deleted
service "helloworld" deleted
virtualservice.networking.istio.io "helloworld-foo" deleted
virtualservice.networking.istio.io "helloworld-default" deleted
```
# Links of interest
- https://istio.io/latest/docs/reference/config/networking/gateway/

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03-Gateway_Ingress/02-Target_Namespace/Service.yaml Normal file
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apiVersion: v1
kind: Service
metadata:
name: helloworld
labels:
app: helloworld
service: helloworld
spec:
ports:
- port: 80
name: http
selector:
app: helloworld

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03-Gateway_Ingress/02-Target_Namespace/VirtualService.yaml Executable file
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apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld-foo
namespace: foo
spec:
hosts:
- "*"
gateways:
- default/helloworld-gateway
http:
- match:
- uri:
exact: /helloworld
route:
- destination:
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite:
uri: "/"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld-default
namespace: default
spec:
hosts:
- "*"
gateways:
- default/helloworld-gateway
http:
- match:
- uri:
exact: /failure
route:
- destination:
host: helloworld.default.svc.cluster.local
port:
number: 80
rewrite:
uri: "/"