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Ruslan Savchuk 2025-04-03 23:07:22 +02:00
parent 7a786179c6
commit af20d996ed
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3
docs/02-kubelet.md
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@ -23,8 +23,7 @@ So, let's begin.
First of all, we need to download kubelet. First of all, we need to download kubelet.
```bash ```bash
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
https://dl.k8s.io/v1.32.3/kubernetes-node-linux-amd64.tar.gz https://dl.k8s.io/v1.32.3/bin/linux/amd64/kubelet
tar -xvzf kubernetes-node-linux-amd64.tar.gz tar -xvzf kubernetes-node-linux-amd64.tar.gz
``` ```

6
docs/04-etcd.md
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@ -38,7 +38,7 @@ After the tools are installed successfully, we need to generate ca certificate.
A ca (Certificate Authority) certificate, also known as a root certificate or a trusted root certificate, is a digital certificate that is used to verify the authenticity of other certificates. A ca (Certificate Authority) certificate, also known as a root certificate or a trusted root certificate, is a digital certificate that is used to verify the authenticity of other certificates.
```bash ```bash
{ {
cat > ca-config.json <<EOF cat <<EOF | tee ca-config.json
{ {
"signing": { "signing": {
"default": { "default": {
@ -54,7 +54,7 @@ cat > ca-config.json <<EOF
} }
EOF EOF
cat > ca-csr.json <<EOF cat <<EOF | tee ca-csr.json
{ {
"CN": "Kubernetes", "CN": "Kubernetes",
"key": { "key": {
@ -92,7 +92,7 @@ Now, we can create certificate files signed by our ca file.
HOST_NAME=$(hostname -a) HOST_NAME=$(hostname -a)
KUBERNETES_HOSTNAMES=kubernetes,kubernetes.default,kubernetes.default.svc,kubernetes.default.svc.cluster,kubernetes.svc.cluster.local KUBERNETES_HOSTNAMES=kubernetes,kubernetes.default,kubernetes.default.svc,kubernetes.default.svc.cluster,kubernetes.svc.cluster.local
cat > kubernetes-csr.json <<EOF cat <<EOF | tee kubernetes-csr.json
{ {
"CN": "kubernetes", "CN": "kubernetes",
"key": { "key": {

42
docs/05-apiserver.md
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@ -13,7 +13,7 @@ As you can see from the description, api server is a central (not the main) comp
Before we begin with the configuration of the api server, we need to create certificates for kubernetes that will be used to sign service account tokens. Before we begin with the configuration of the api server, we need to create certificates for kubernetes that will be used to sign service account tokens.
```bash ```bash
{ {
cat > service-account-csr.json <<EOF cat <<EOF | tee service-account-csr.json
{ {
"CN": "service-accounts", "CN": "service-accounts",
"key": { "key": {
@ -43,14 +43,11 @@ cfssl gencert \
Now, we need to distribute certificates to the api server configuration folder Now, we need to distribute certificates to the api server configuration folder
```bash ```bash
{ mkdir -p /var/lib/kubernetes/ \
mkdir /var/lib/kubernetes/ && cp \
sudo cp \ ca.pem kubernetes.pem kubernetes-key.pem \
ca.pem \
kubernetes.pem kubernetes-key.pem \
service-account-key.pem service-account.pem \ service-account-key.pem service-account.pem \
/var/lib/kubernetes/ /var/lib/kubernetes/
}
``` ```
As you can see, in addition to the generated service-account certificate file, we also distributed the certificate generated in the [previous](./04-etcd.md) section. We will use that certificate for communication between As you can see, in addition to the generated service-account certificate file, we also distributed the certificate generated in the [previous](./04-etcd.md) section. We will use that certificate for communication between
@ -89,19 +86,21 @@ Now, when all required configuration/certificate files are created and distribut
First of all, we need to download and install api server binaries First of all, we need to download and install api server binaries
https://kubernetes.io/releases/download/
```bash ```bash
{
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
"https://storage.googleapis.com/kubernetes-release/release/v1.21.0/bin/linux/amd64/kube-apiserver" "https://dl.k8s.io/v1.32.3/bin/linux/amd64/kube-apiserver"
chmod +x kube-apiserver ```
sudo mv kube-apiserver /usr/local/bin/
} ```bash
chmod +x kube-apiserver \
&& mv kube-apiserver /usr/local/bin/
``` ```
And create the service configuration file And create the service configuration file
```bash ```bash
cat <<EOF | sudo tee /etc/systemd/system/kube-apiserver.service cat <<EOF | tee /etc/systemd/system/kube-apiserver.service
[Unit] [Unit]
Description=Kubernetes API Server Description=Kubernetes API Server
Documentation=https://github.com/kubernetes/kubernetes Documentation=https://github.com/kubernetes/kubernetes
@ -149,16 +148,14 @@ Configuration options I want to highlight:
Now, when api-server service is configured, we can start it Now, when api-server service is configured, we can start it
```bash ```bash
{ systemctl daemon-reload \
sudo systemctl daemon-reload && systemctl enable kube-apiserver \
sudo systemctl enable kube-apiserver && systemctl start kube-apiserver
sudo systemctl start kube-apiserver
}
``` ```
And check the service status And check the service status
```bash ```bash
sudo systemctl status kube-apiserver systemctl status kube-apiserver
``` ```
Output: Output:
@ -180,9 +177,9 @@ Now, when our server is up and running, we want to communicate with it. To do th
```bash ```bash
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
https://storage.googleapis.com/kubernetes-release/release/v1.21.0/bin/linux/amd64/kubectl \ https://dl.k8s.io/v1.32.3/bin/linux/386/kubectl \
&& chmod +x kubectl \ && chmod +x kubectl \
&& sudo mv kubectl /usr/local/bin/ && mv kubectl /usr/local/bin/
``` ```
As the api server is configured in more or less secure mode, we need to provide some credentials when accessing it. We will use certificate files as the credentials. That is why we need to generate a proper certificate file that will allow us to access api server with administrator privileges As the api server is configured in more or less secure mode, we need to provide some credentials when accessing it. We will use certificate files as the credentials. That is why we need to generate a proper certificate file that will allow us to access api server with administrator privileges
@ -252,7 +249,7 @@ As already mentioned, api-server is the central kubernetes component, that store
It means that we can create a pod, even when other components (kubelet, scheduler, controller manager) are not configured It means that we can create a pod, even when other components (kubelet, scheduler, controller manager) are not configured
```bash ```bash
{ {
HOST_NAME=$(hostname -a) HOST_NAME=$(cat /etc/hostname)
cat <<EOF> pod.yaml cat <<EOF> pod.yaml
apiVersion: v1 apiVersion: v1
@ -261,6 +258,7 @@ metadata:
name: hello-world name: hello-world
spec: spec:
serviceAccountName: hello-world serviceAccountName: hello-world
terminationGracePeriodSeconds: 1
containers: containers:
- name: hello-world-container - name: hello-world-container
image: busybox image: busybox

56
docs/06-apiserver-kubelet.md
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@ -10,8 +10,8 @@ Again we will start this part with the creation of the certificates which will b
```bash ```bash
{ {
HOST_NAME=$(hostname -a) HOST_NAME=$(cat /etc/hostname)
cat > kubelet-csr.json <<EOF cat <<EOF | tee kubelet-csr.json
{ {
"CN": "system:node:${HOST_NAME}", "CN": "system:node:${HOST_NAME}",
"key": { "key": {
@ -56,10 +56,8 @@ We specified "system:nodes" in the organization. It says api server that the cli
Now we need to distribute certificates generated. Now we need to distribute certificates generated.
```bash ```bash
{ cp kubelet-key.pem kubelet.pem /var/lib/kubelet/ \
sudo cp kubelet-key.pem kubelet.pem /var/lib/kubelet/ && cp ca.pem /var/lib/kubernetes/
sudo cp ca.pem /var/lib/kubernetes/
}
``` ```
## service configuration ## service configuration
@ -68,7 +66,7 @@ After certificates configured and distributed, we need to prepare configuration
```bash ```bash
{ {
HOST_NAME=$(hostname -a) HOST_NAME=$(cat /etc/hostname)
kubectl config set-cluster kubernetes-the-hard-way \ kubectl config set-cluster kubernetes-the-hard-way \
--certificate-authority=ca.pem \ --certificate-authority=ca.pem \
--embed-certs=true \ --embed-certs=true \
@ -95,29 +93,24 @@ We created kubernetes configuration file, which says kubelet where api server is
And now, move all our configuration settings to the proper folders And now, move all our configuration settings to the proper folders
```bash ```bash
sudo cp kubelet.kubeconfig /var/lib/kubelet/kubeconfig cp kubelet.kubeconfig /var/lib/kubelet/kubeconfig
``` ```
Also, we need to create KubeletConfiguration Also, we need to create KubeletConfiguration
```bash ```bash
cat <<EOF | sudo tee /var/lib/kubelet/kubelet-config.yaml cat <<EOF | tee /var/lib/kubelet/kubelet-config.yaml
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1 apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
authentication: authentication:
anonymous: anonymous:
enabled: false
webhook:
enabled: true enabled: true
x509: webhook:
clientCAFile: "/var/lib/kubernetes/ca.pem" enabled: false
authorization: authorization:
mode: Webhook mode: AlwaysAllow
clusterDomain: "cluster.local" networkPlugin: "cni"
clusterDNS: cniConfDir: "/etc/cni/net.d"
- "10.32.0.10" cniBinDir: "/opt/cni/bin"
podCIDR: "10.240.1.0/24"
resolvConf: "/run/systemd/resolve/resolv.conf"
runtimeRequestTimeout: "15m"
tlsCertFile: "/var/lib/kubelet/kubelet.pem" tlsCertFile: "/var/lib/kubelet/kubelet.pem"
tlsPrivateKeyFile: "/var/lib/kubelet/kubelet-key.pem" tlsPrivateKeyFile: "/var/lib/kubelet/kubelet-key.pem"
EOF EOF
@ -131,7 +124,7 @@ Configuration options I want to highlight:
And the last step - we need to update service configuration file And the last step - we need to update service configuration file
```bash ```bash
cat <<EOF | sudo tee /etc/systemd/system/kubelet.service cat <<EOF | tee /etc/systemd/system/kubelet.service
[Unit] [Unit]
Description=Kubernetes Kubelet Description=Kubernetes Kubelet
Documentation=https://github.com/kubernetes/kubernetes Documentation=https://github.com/kubernetes/kubernetes
@ -140,14 +133,13 @@ Requires=containerd.service
[Service] [Service]
ExecStart=/usr/local/bin/kubelet \\ ExecStart=/usr/local/bin/kubelet \\
--config=/var/lib/kubelet/kubelet-config.yaml \\
--container-runtime=remote \\
--container-runtime-endpoint=unix:///var/run/containerd/containerd.sock \\ --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock \\
--image-pull-progress-deadline=2m \\ --file-check-frequency=10s \\
--config=/var/lib/kubelet/kubelet-config.yaml \\
--pod-manifest-path='/etc/kubernetes/manifests/' \\
--kubeconfig=/var/lib/kubelet/kubeconfig \\ --kubeconfig=/var/lib/kubelet/kubeconfig \\
--network-plugin=cni \\
--register-node=true \\ --register-node=true \\
--v=2 --v=10
Restart=on-failure Restart=on-failure
RestartSec=5 RestartSec=5
@ -159,18 +151,16 @@ EOF
And reload it And reload it
```bash ```bash
{ systemctl daemon-reload \
sudo systemctl daemon-reload && systemctl enable kubelet \
sudo systemctl enable kubelet && systemctl restart kubelet
sudo systemctl restart kubelet
}
``` ```
## verification ## verification
And check service status And check service status
```bash ```bash
sudo systemctl status kubelet systemctl status kubelet
``` ```
Output: Output:

33
docs/07-scheduler.md
View File

@ -23,6 +23,7 @@ metadata:
name: hello-world name: hello-world
spec: spec:
serviceAccountName: hello-world serviceAccountName: hello-world
terminationGracePeriodSeconds: 1
containers: containers:
- name: hello-world-container - name: hello-world-container
image: busybox image: busybox
@ -121,16 +122,16 @@ We created kubernetes configuration file, which says scheduler where api server
Now, we can distribute created configuration file. Now, we can distribute created configuration file.
```bash ```bash
sudo mv kube-scheduler.kubeconfig /var/lib/kubernetes/ mv kube-scheduler.kubeconfig /var/lib/kubernetes/
``` ```
In addition to this file, we will create one more configuration file for scheduler In addition to this file, we will create one more configuration file for scheduler
```bash ```bash
{ {
mkdir /etc/kubernetes/config mkdir -p /etc/kubernetes/config
cat <<EOF | sudo tee /etc/kubernetes/config/kube-scheduler.yaml cat <<EOF | tee /etc/kubernetes/config/kube-scheduler.yaml
apiVersion: kubescheduler.config.k8s.io/v1beta1 apiVersion: kubescheduler.config.k8s.io/v1
kind: KubeSchedulerConfiguration kind: KubeSchedulerConfiguration
clientConnection: clientConnection:
kubeconfig: "/var/lib/kubernetes/kube-scheduler.kubeconfig" kubeconfig: "/var/lib/kubernetes/kube-scheduler.kubeconfig"
@ -144,21 +145,19 @@ After all configuration files created, we need to download scheduler binaries.
```bash ```bash
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
"https://storage.googleapis.com/kubernetes-release/release/v1.21.0/bin/linux/amd64/kube-scheduler" "https://dl.k8s.io/v1.32.3/bin/linux/amd64/kube-scheduler"
``` ```
And install it And install it
```bash ```bash
{ chmod +x kube-scheduler \
chmod +x kube-scheduler && mv kube-scheduler /usr/local/bin/
sudo mv kube-scheduler /usr/local/bin/
}
``` ```
Now, we can create configuration file for scheduler service Now, we can create configuration file for scheduler service
```bash ```bash
cat <<EOF | sudo tee /etc/systemd/system/kube-scheduler.service cat <<EOF | tee /etc/systemd/system/kube-scheduler.service
[Unit] [Unit]
Description=Kubernetes Scheduler Description=Kubernetes Scheduler
Documentation=https://github.com/kubernetes/kubernetes Documentation=https://github.com/kubernetes/kubernetes
@ -178,17 +177,15 @@ EOF
After configuration file created, we need to run it After configuration file created, we need to run it
```bash ```bash
{ systemctl daemon-reload \
sudo systemctl daemon-reload && systemctl enable kube-scheduler \
sudo systemctl enable kube-scheduler && systemctl start kube-scheduler
sudo systemctl start kube-scheduler
}
``` ```
And finally we check scheduler status And finally we check scheduler status
```bash ```bash
sudo systemctl status kube-scheduler systemctl status kube-scheduler
``` ```
Output: Output:
@ -235,7 +232,7 @@ May 21 20:52:25 example-server kube-scheduler[91664]: I0521 20:52:25.471604 91
As we can see our pod wasn't assigned to the node because node has some taint, lets check our node taints. As we can see our pod wasn't assigned to the node because node has some taint, lets check our node taints.
```bash ```bash
kubectl get nodes $(hostname -a) -o jsonpath='{.spec.taints}' kubectl get nodes $(cat /etc/hostname) -o jsonpath='{.spec.taints}'
``` ```
Output: Output:
@ -246,7 +243,7 @@ Output:
As you can see, our node has taint with efect no schedule. As you can see, our node has taint with efect no schedule.
Lets fix this. Lets fix this.
```bash ```bash
kubectl taint nodes $(hostname -a) node.kubernetes.io/not-ready:NoSchedule- kubectl taint nodes $(cat /etc/hostname) node.kubernetes.io/not-ready:NoSchedule-
``` ```
And check our pods list again And check our pods list again

24
docs/08-controller-manager.md
View File

@ -102,7 +102,7 @@ We specified "system:kube-controller-manager" in the organization. It says api s
Now, we will distribute ca certificate, this ???? Now, we will distribute ca certificate, this ????
```bash ```bash
sudo cp ca-key.pem /var/lib/kubernetes/ cp ca-key.pem /var/lib/kubernetes/
``` ```
## configuration ## configuration
@ -136,26 +136,24 @@ We created kubernetes configuration file, which says controller manager where ap
Now, we can distribute created configuration file. Now, we can distribute created configuration file.
```bash ```bash
sudo mv kube-controller-manager.kubeconfig /var/lib/kubernetes/ mv kube-controller-manager.kubeconfig /var/lib/kubernetes/
``` ```
After all required configuration file created, we need to download controller manager binaries. After all required configuration file created, we need to download controller manager binaries.
```bash ```bash
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
"https://storage.googleapis.com/kubernetes-release/release/v1.21.0/bin/linux/amd64/kube-controller-manager" "https://dl.k8s.io/v1.32.3/bin/linux/amd64/kube-controller-manager"
``` ```
And install it And install it
```bash ```bash
{ chmod +x kube-controller-manager \
chmod +x kube-controller-manager && mv kube-controller-manager /usr/local/bin/
sudo mv kube-controller-manager /usr/local/bin/
}
``` ```
Now, we can create configuration file for controller manager service Now, we can create configuration file for controller manager service
```bash ```bash
cat <<EOF | sudo tee /etc/systemd/system/kube-controller-manager.service cat <<EOF | tee /etc/systemd/system/kube-controller-manager.service
[Unit] [Unit]
Description=Kubernetes Controller Manager Description=Kubernetes Controller Manager
Documentation=https://github.com/kubernetes/kubernetes Documentation=https://github.com/kubernetes/kubernetes
@ -184,16 +182,14 @@ EOF
After configuration file created, we can start controller manager After configuration file created, we can start controller manager
```bash ```bash
{ systemctl daemon-reload \
sudo systemctl daemon-reload && systemctl enable kube-controller-manager \
sudo systemctl enable kube-controller-manager && systemctl start kube-controller-manager
sudo systemctl start kube-controller-manager
}
``` ```
And finaly we can check controller manadger status And finaly we can check controller manadger status
```bash ```bash
sudo systemctl status kube-controller-manager systemctl status kube-controller-manager
``` ```
Output: Output:

38
docs/09-kubeproxy.md
View File

@ -9,7 +9,7 @@ In this section we will configure kupe-proxy.
Before we will start, lets clarify the reason why do we need it. To do that, we will create deployment with nginx. Before we will start, lets clarify the reason why do we need it. To do that, we will create deployment with nginx.
```bash ```bash
{ {
cat <<EOF> nginx-deployment.yml cat <<EOF | tee nginx-deployment.yml
apiVersion: v1 apiVersion: v1
kind: ConfigMap kind: ConfigMap
metadata: metadata:
@ -71,7 +71,7 @@ nginx-deployment-db9778f94-twx78 1/1 Running 0 63s 10.240.1.1
As you an see, we created 3 pods (each has its own ip address). Now, we will run busybox container and will try to access our pods from other container As you an see, we created 3 pods (each has its own ip address). Now, we will run busybox container and will try to access our pods from other container
```bash ```bash
{ {
cat <<EOF> pod.yaml cat <<EOF | tee pod.yaml
apiVersion: v1 apiVersion: v1
kind: Pod kind: Pod
metadata: metadata:
@ -100,7 +100,7 @@ error: unable to upgrade connection: Forbidden (user=kubernetes, verb=create, re
This error occured, because api server has no access to execute commands. We will fix this issue, by creating cluster role and assigning it role to kubernetes user. This error occured, because api server has no access to execute commands. We will fix this issue, by creating cluster role and assigning it role to kubernetes user.
```bash ```bash
{ {
cat <<EOF> rbac-create.yml cat <<EOF | tee rbac-create.yml
kind: ClusterRole kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1 apiVersion: rbac.authorization.k8s.io/v1
metadata: metadata:
@ -149,7 +149,7 @@ Note: it take some time to apply user permission. During this you can steel see
As you can see, we successfully received the response from the nginx. But to do that we used the IP address of the pod. To solve service discovery issue, kubernetes has special component - service. Now we will create it. As you can see, we successfully received the response from the nginx. But to do that we used the IP address of the pod. To solve service discovery issue, kubernetes has special component - service. Now we will create it.
```bash ```bash
{ {
cat <<EOF> nginx-service.yml cat <<EOF | tee nginx-service.yml
apiVersion: v1 apiVersion: v1
kind: Service kind: Service
metadata: metadata:
@ -192,7 +192,7 @@ As you remeber we configured our API server to use client certificate to authent
So, lets create proper certificate for the kube-proxy So, lets create proper certificate for the kube-proxy
```bash ```bash
{ {
cat > kube-proxy-csr.json <<EOF cat <<EOF | tee kube-proxy-csr.json
{ {
"CN": "system:kube-proxy", "CN": "system:kube-proxy",
"key": { "key": {
@ -257,30 +257,26 @@ We created kubernetes configuration file, which says kube-proxy where api server
Now, we can distribute created configuration file. Now, we can distribute created configuration file.
```bash ```bash
{ mkdir -p /var/lib/kube-proxy \
sudo mkdir -p /var/lib/kube-proxy && mv kube-proxy.kubeconfig /var/lib/kube-proxy/kubeconfig
sudo mv kube-proxy.kubeconfig /var/lib/kube-proxy/kubeconfig
}
``` ```
After all required configuration file created, we need to download kube-proxy binaries. After all required configuration file created, we need to download kube-proxy binaries.
```bash ```bash
wget -q --show-progress --https-only --timestamping \ wget -q --show-progress --https-only --timestamping \
https://storage.googleapis.com/kubernetes-release/release/v1.21.0/bin/linux/amd64/kube-proxy https://dl.k8s.io/v1.32.3/bin/linux/amd64/kube-proxy
``` ```
And install it And install it
```bash ```bash
{ chmod +x kube-proxy \
chmod +x kube-proxy && mv kube-proxy /usr/local/bin/
sudo mv kube-proxy /usr/local/bin/
}
``` ```
Now, we can create configuration file for kube-proxy Now, we can create configuration file for kube-proxy
```bash ```bash
cat <<EOF | sudo tee /var/lib/kube-proxy/kube-proxy-config.yaml cat <<EOF | tee /var/lib/kube-proxy/kube-proxy-config.yaml
kind: KubeProxyConfiguration kind: KubeProxyConfiguration
apiVersion: kubeproxy.config.k8s.io/v1alpha1 apiVersion: kubeproxy.config.k8s.io/v1alpha1
clientConnection: clientConnection:
@ -292,7 +288,7 @@ EOF
Service configuration file Service configuration file
```bash ```bash
cat <<EOF | sudo tee /etc/systemd/system/kube-proxy.service cat <<EOF | tee /etc/systemd/system/kube-proxy.service
[Unit] [Unit]
Description=Kubernetes Kube Proxy Description=Kubernetes Kube Proxy
Documentation=https://github.com/kubernetes/kubernetes Documentation=https://github.com/kubernetes/kubernetes
@ -310,16 +306,14 @@ EOF
Start service Start service
```bash ```bash
{ systemctl daemon-reload \
sudo systemctl daemon-reload && systemctl enable kube-proxy \
sudo systemctl enable kube-proxy && systemctl start kube-proxy
sudo systemctl start kube-proxy
}
``` ```
And check its status And check its status
```bash ```bash
sudo systemctl status kube-proxy systemctl status kube-proxy
``` ```
Output: Output:

4
docs/10-dns.md
View File

@ -11,7 +11,7 @@ If you remember, in previous section we accessed service by using its IP address
Befire we will configure it, we can check if we can access our service (created in previuos section) by its name. Befire we will configure it, we can check if we can access our service (created in previuos section) by its name.
```bash ```bash
kubectl exec busy-box -- wget -O - nginx-service kubectl exec busy-box -- wget -O - nginx-service.default.svc.cluster.local.
``` ```
And nothing happen. The reason of this befaviour - pod can't resolve IP address of the domain name requested as DNS server is not configured in our cluster. And nothing happen. The reason of this befaviour - pod can't resolve IP address of the domain name requested as DNS server is not configured in our cluster.
@ -31,7 +31,7 @@ kubectl apply -f https://raw.githubusercontent.com/ruslansavchuk/kubernetes-the-
After our DNS server is up and running, we can try to repeat the call once again After our DNS server is up and running, we can try to repeat the call once again
```bash ```bash
kubectl exec busy-box -- wget -O - nginx-service kubectl exec busy-box -- wget -O - nginx-service.default.svc.cluster.local.
``` ```
Output: Output: