Kubernetes (K8s) uses a containerization platform like Docker, containerd, etc. and requires a Registry to download and use Docker images. Docker Hub is the global public registry that serves the purpose. However, there are situations, when we want to use Kubernetes (K8s) in a private network. In such a situation, we cannot access Docker Hub, therefore, we must configure a Private Docker Registry for our Kubernetes (K8s) cluster.
In this article, we will install Kubernetes (K8s) offline on CentOS 7. We are not configuring a Private Docker Registry here, but you can read our following articles to configure it by yourself.
- Configure Secure Registry with Docker-Distribution on CentOS 7
- Configure a Private Docker Registry on CentOS 7
For understanding Kubernetes (K8s) concepts and use it in your environment, we recommend that you should read Kubernetes in Action by Manning Publications.
This Article Provides:
System Specification:
We have configured two CentOS 7 virtual machines.
| Hostname: | docker-online.example.com | docker-offline.example.com |
| Operating System: | CentOS 7.6 | CentOS 7.6 |
| Internet: | Yes | No |
| Docker Version: | Docker CE 18.09 | Docker CE 18.09 |
Installing Docker Offline on CentOS 7:
We have already written a complete article Install Docker CE on an Offline CentOS 7 Machine. Therefore, it is advised that, you should follow that article to install Docker CE before Kubernetes (K8s) installation on both machines.
We are also required to install Docker CE on docker-online.example.com, because we will pull required images from Docker Hub using docker command.
Connect with docker-offline.example.com using ssh as root user.
After installing Docker CE, we must configure it to use with Kubernetes (K8s).
[root@docker-offline ~]# mkdir /etc/docker
[root@docker-offline ~]# cat > /etc/docker/daemon.json << EOF
> {
> "exec-opts": ["native.cgroupdriver=systemd"],
> "log-driver": "json-file",
> "log-opts": {
> "max-size": "100m"
> },
> "storage-driver": "overlay2",
> "storage-opts": [
> "overlay2.override_kernel_check=true"
> ]
> }
> EOF
Restart docker.service.
[root@docker-offline ~]# systemctl restart docker.service
Downloading Packages/Images for Offline Installation of Kubernetes (K8s):
Connect with docker-online.example.com using ssh as root user.
Add Kubernetes (K8s) yum repository as follows:
[root@docker-online k8s]# cat > /etc/yum.repos.d/kubernetes.repo << EOF
> [kubernetes]
> name=Kubernetes
> baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
> enabled=1
> gpgcheck=1
> repo_gpgcheck=1
> gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
> EOF
Build yum cache.
[root@docker-online ~]# yum makecache fast
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
epel/x86_64/metalink | 6.7 kB 00:00
* base: mirrors.ges.net.pk
* epel: mirror1.ku.ac.th
* extras: mirrors.ges.net.pk
* updates: mirrors.ges.net.pk
base | 3.6 kB 00:00
docker-ce-nightly | 3.5 kB 00:00
docker-ce-stable | 3.5 kB 00:00
extras | 3.4 kB 00:00
kubernetes/signature | 454 B 00:00
Retrieving key from https://packages.cloud.google.com/yum/doc/yum-key.gpg
Importing GPG key 0xA7317B0F:
Userid : "Google Cloud Packages Automatic Signing Key <gc-team@google.com>"
Fingerprint: d0bc 747f d8ca f711 7500 d6fa 3746 c208 a731 7b0f
From : https://packages.cloud.google.com/yum/doc/yum-key.gpg
Is this ok [y/N]: y
Retrieving key from https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
kubernetes/signature | 1.4 kB 00:06 !!!
updates | 3.4 kB 00:00
kubernetes/primary | 47 kB 00:03
kubernetes 342/342
Metadata Cache Created
Create a directory to download required Kubernetes (K8s) packages.
[root@docker-online ~]# mkdir ~/k8s
[root@docker-online k8s]# cd ~/k8s
Download Kubernetes (K8s) packages using yumdownloader.
[root@docker-online k8s]# yumdownloader --resolve kubelet kubeadm kubectl
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.ges.net.pk
* epel: kartolo.sby.datautama.net.id
* extras: mirrors.ges.net.pk
* updates: mirrors.ges.net.pk
--> Running transaction check
---> Package kubeadm.x86_64 0:1.14.1-0 will be installed
--> Processing Dependency: kubernetes-cni >= 0.7.5 for package: kubeadm-1.14.1-0.x86_64
--> Processing Dependency: cri-tools >= 1.11.0 for package: kubeadm-1.14.1-0.x86_64
---> Package kubectl.x86_64 0:1.14.1-0 will be installed
---> Package kubelet.x86_64 0:1.14.1-0 will be installed
--> Processing Dependency: socat for package: kubelet-1.14.1-0.x86_64
--> Processing Dependency: conntrack for package: kubelet-1.14.1-0.x86_64
--> Running transaction check
---> Package conntrack-tools.x86_64 0:1.4.4-4.el7 will be installed
--> Processing Dependency: libnetfilter_cttimeout.so.1(LIBNETFILTER_CTTIMEOUT_1.1)(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
--> Processing Dependency: libnetfilter_cttimeout.so.1(LIBNETFILTER_CTTIMEOUT_1.0)(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
--> Processing Dependency: libnetfilter_cthelper.so.0(LIBNETFILTER_CTHELPER_1.0)(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
--> Processing Dependency: libnetfilter_queue.so.1()(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
--> Processing Dependency: libnetfilter_cttimeout.so.1()(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
--> Processing Dependency: libnetfilter_cthelper.so.0()(64bit) for package: conntrack-tools-1.4.4-4.el7.x86_64
---> Package cri-tools.x86_64 0:1.12.0-0 will be installed
---> Package kubernetes-cni.x86_64 0:0.7.5-0 will be installed
---> Package socat.x86_64 0:1.7.3.2-2.el7 will be installed
--> Running transaction check
---> Package libnetfilter_cthelper.x86_64 0:1.0.0-9.el7 will be installed
---> Package libnetfilter_cttimeout.x86_64 0:1.0.0-6.el7 will be installed
---> Package libnetfilter_queue.x86_64 0:1.0.2-2.el7_2 will be installed
--> Finished Dependency Resolution
(1/10): conntrack-tools-1.4.4-4.el7.x86_64.rpm | 186 kB 00:03
warning: /root/k8s/53edc739a0e51a4c17794de26b13ee5df939bd3161b37f503fe2af8980b41a89-cri-tools-1.12.0-0.x86_64.rpm: Header V4 RSA/SHA512 Signature, key ID 3e1ba8d5: NOKEY
Public key for 53edc739a0e51a4c17794de26b13ee5df939bd3161b37f503fe2af8980b41a89-cri-tools-1.12.0-0.x86_64.rpm is not installed
(2/10): 53edc739a0e51a4c17794de26b13ee5df939bd3161b37f503f | 4.2 MB 00:21
(3/10): 9e1af74c18311f2f6f8460dbd1aa3e02911105bfd455416381 | 8.7 MB 00:45
(4/10): 5c6cb3beb5142fa21020e2116824ba77a2d1389a3321601ea5 | 9.5 MB 00:42
(5/10): libnetfilter_cthelper-1.0.0-9.el7.x86_64.rpm | 18 kB 00:02
(6/10): libnetfilter_cttimeout-1.0.0-6.el7.x86_64.rpm | 18 kB 00:03
(7/10): libnetfilter_queue-1.0.2-2.el7_2.x86_64.rpm | 23 kB 00:03
(8/10): socat-1.7.3.2-2.el7.x86_64.rpm | 290 kB 00:02
(9/10): 548a0dcd865c16a50980420ddfa5fbccb8b59621179798e6dc | 10 MB 00:46
(10/10): e1e8f430609698d7ec87642179ab57605925cb9aa48d406da | 23 MB 01:27
List downloaded files.
[root@docker-online k8s]# ls
53edc739a0e51a4c17794de26b13ee5df939bd3161b37f503fe2af8980b41a89-cri-tools-1.12.0-0.x86_64.rpm
548a0dcd865c16a50980420ddfa5fbccb8b59621179798e6dc905c9bf8af3b34-kubernetes-cni-0.7.5-0.x86_64.rpm
5c6cb3beb5142fa21020e2116824ba77a2d1389a3321601ea53af5ceefe70ad1-kubectl-1.14.1-0.x86_64.rpm
9e1af74c18311f2f6f8460dbd1aa3e02911105bfd455416381e995d8172a0a01-kubeadm-1.14.1-0.x86_64.rpm
conntrack-tools-1.4.4-4.el7.x86_64.rpm
e1e8f430609698d7ec87642179ab57605925cb9aa48d406da97dedfb629bebf2-kubelet-1.14.1-0.x86_64.rpm
libnetfilter_cthelper-1.0.0-9.el7.x86_64.rpm
libnetfilter_cttimeout-1.0.0-6.el7.x86_64.rpm
libnetfilter_queue-1.0.2-2.el7_2.x86_64.rpm
socat-1.7.3.2-2.el7.x86_64.rpm
Download Docker images from Docker Hub, as required by Kubernetes (K8s) for node initialization.
[root@docker-online ~]# docker pull k8s.gcr.io/kube-apiserver:v1.14.1
v1.14.1: Pulling from kube-apiserver
346aee5ea5bc: Pull complete
7f0e834d5a94: Pull complete
Digest: sha256:bb3e3264bf74cc6929ec05b494d95b7aed9ee1e5c1a5c8e0693b0f89e2e7288e
Status: Downloaded newer image for k8s.gcr.io/kube-apiserver:v1.14.1
[root@docker-online ~]# docker pull k8s.gcr.io/kube-controller-manager:v1.14.1
v1.14.1: Pulling from kube-controller-manager
346aee5ea5bc: Already exists
f4db69ee8ade: Pull complete
Digest: sha256:5279e0030094c0ef2ba183bd9627e91e74987477218396bd97a5e070df241df5
Status: Downloaded newer image for k8s.gcr.io/kube-controller-manager:v1.14.1
[root@docker-online ~]# docker pull k8s.gcr.io/kube-scheduler:v1.14.1
v1.14.1: Pulling from kube-scheduler
346aee5ea5bc: Already exists
b88909b8f99f: Pull complete
Digest: sha256:11af0ae34bc63cdc78b8bd3256dff1ba96bf2eee4849912047dee3e420b52f8f
Status: Downloaded newer image for k8s.gcr.io/kube-scheduler:v1.14.1
[root@docker-online ~]# docker pull k8s.gcr.io/kube-proxy:v1.14.1
v1.14.1: Pulling from kube-proxy
346aee5ea5bc: Already exists
1e695dec1fee: Pull complete
100690d61cf6: Pull complete
Digest: sha256:44af2833c6cbd9a7fc2e9d2f5244a39dfd2e31ad91bf9d4b7d810678db738ee9
Status: Downloaded newer image for k8s.gcr.io/kube-proxy:v1.14.1
[root@docker-online ~]# docker pull k8s.gcr.io/pause:3.1
3.1: Pulling from pause
67ddbfb20a22: Pull complete
Digest: sha256:f78411e19d84a252e53bff71a4407a5686c46983a2c2eeed83929b888179acea
Status: Downloaded newer image for k8s.gcr.io/pause:3.1
[root@docker-online ~]# docker pull k8s.gcr.io/etcd:3.3.10
3.3.10: Pulling from etcd
90e01955edcd: Pull complete
6369547c492e: Pull complete
bd2b173236d3: Pull complete
Digest: sha256:17da501f5d2a675be46040422a27b7cc21b8a43895ac998b171db1c346f361f7
Status: Downloaded newer image for k8s.gcr.io/etcd:3.3.10
[root@docker-online ~]# docker pull k8s.gcr.io/coredns:1.3.1
1.3.1: Pulling from coredns
e0daa8927b68: Pull complete
3928e47de029: Pull complete
Digest: sha256:02382353821b12c21b062c59184e227e001079bb13ebd01f9d3270ba0fcbf1e4
Status: Downloaded newer image for k8s.gcr.io/coredns:1.3.1
List Docker images.
[root@docker-online ~]# docker image ls -a
REPOSITORY TAG IMAGE ID CREATED SIZE
k8s.gcr.io/kube-proxy v1.14.1 20a2d7035165 2 weeks ago 82.1MB
k8s.gcr.io/kube-apiserver v1.14.1 cfaa4ad74c37 2 weeks ago 210MB
k8s.gcr.io/kube-controller-manager v1.14.1 efb3887b411d 2 weeks ago 158MB
k8s.gcr.io/kube-scheduler v1.14.1 8931473d5bdb 2 weeks ago 81.6MB
k8s.gcr.io/coredns 1.3.1 eb516548c180 3 months ago 40.3MB
k8s.gcr.io/etcd 3.3.10 2c4adeb21b4f 4 months ago 258MB
k8s.gcr.io/pause 3.1 da86e6ba6ca1 16 months ago 742kB
Export Kubernetes (K8s) related Docker images to individual tar files.
[root@docker-online ~]# docker save k8s.gcr.io/kube-apiserver:v1.14.1 > ~/k8s/kube-apiserver.tar
[root@docker-online ~]# docker save k8s.gcr.io/kube-controller-manager:v1.14.1 > ~/k8s/kube-controller-manager.tar
[root@docker-online ~]# docker save k8s.gcr.io/kube-scheduler:v1.14.1 > ~/k8s/kube-scheduler.tar
[root@docker-online ~]# docker save k8s.gcr.io/kube-proxy:v1.14.1 > ~/k8s/kube-proxy.tar
[root@docker-online ~]# docker save k8s.gcr.io/pause:3.1 > ~/k8s/pause.tar
[root@docker-online ~]# docker save k8s.gcr.io/etcd:3.3.10 > ~/k8s/etcd.tar
[root@docker-online ~]# docker save k8s.gcr.io/coredns:1.3.1 > ~/k8s/coredns.tar
List tar files.
[root@docker-online ~]# ls ~/k8s/*.tar
/root/k8s/coredns.tar /root/k8s/kube-proxy.tar
/root/k8s/etcd.tar /root/k8s/kube-scheduler.tar
/root/k8s/kube-apiserver.tar /root/k8s/pause.tar
/root/k8s/kube-controller-manager.tar
Download Flannel Network script.
[root@docker-online ~]# cd ~/k8s
[root@docker-online k8s]# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
--2019-04-27 20:09:16-- https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.8.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.8.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 12306 (12K) [text/plain]
Saving to: âkube-flannel.ymlâ
100%[======================================>] 12,306 --.-K/s in 0.006s
2019-04-27 20:09:18 (2.11 MB/s) - âkube-flannel.ymlâ saved [12306/12306]
We have successfully downloaded all required files for Kubernetes (K8s) installation.
Transfer the directory ~/k8s from docker-online to docker-offline.
Configuring Prerequisites for Kubernetes (K8s):
Connect with docker-offline.example.com using ssh as root user.
Set Kernel parameter as required by Kubernetes (K8s).
[root@docker-offline ~]# cat > /etc/sysctl.d/kubernetes.conf << EOF
> net.ipv4.ip_forward = 1
> net.bridge.bridge-nf-call-ip6tables = 1
> net.bridge.bridge-nf-call-iptables = 1
> EOF
Reload Kernel parameter configuration files.
[root@docker-offline ~]# modprobe br_netfilter
[root@docker-offline ~]# sysctl --system
* Applying /usr/lib/sysctl.d/00-system.conf ...
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
* Applying /usr/lib/sysctl.d/10-default-yama-scope.conf ...
kernel.yama.ptrace_scope = 0
* Applying /usr/lib/sysctl.d/50-default.conf ...
kernel.sysrq = 16
kernel.core_uses_pid = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.promote_secondaries = 1
net.ipv4.conf.all.promote_secondaries = 1
fs.protected_hardlinks = 1
fs.protected_symlinks = 1
* Applying /etc/sysctl.d/99-sysctl.conf ...
* Applying /etc/sysctl.d/kubernetes.conf ...
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
* Applying /etc/sysctl.conf ...
Turn off Swap for Kubernetes (K8s) installation.
[root@docker-offline ~]# swapoff -a
[root@docker-offline ~]# sed -e '/swap/s/^/#/g' -i /etc/fstab
Allow Kubernetes (K8s) service ports in Linux firewall.
For Master node
[root@docker-offline ~]# firewall-cmd --permanent --add-port={6443,2379,2380,10250,10251,10252}/tcp
success
For Worker nodes
[root@docker-offline ~]# firewall-cmd --permanent --add-port={10250,30000-32767}/tcp
success
Reload firewall configurations.
[root@docker-offline ~]# firewall-cmd --reload
success
Switch SELinux to Permissive mode using following commands.
[root@docker-offline ~]# setenforce 0
[root@docker-offline ~]# sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
Installing Kubernetes (K8s) Offline on CentOS 7:
Now, install Kubernetes (K8s) packages from ~/k8s directory using rpm command.
[root@docker-offline ~]# rpm -ivh --replacefiles --replacepkgs ~/k8s/*.rpm
warning: 53edc739a0e51a4c17794de26b13ee5df939bd3161b37f503fe2af8980b41a89-cri-tools-1.12.0-0.x86_64.rpm: Header V4 RSA/SHA512 Signature, key ID 3e1ba8d5: NOKEY
Preparing... ################################# [100%]
Updating / installing...
1:socat-1.7.3.2-2.el7 ################################# [ 10%]
2:libnetfilter_queue-1.0.2-2.el7_2 ################################# [ 20%]
3:libnetfilter_cttimeout-1.0.0-6.el################################# [ 30%]
4:libnetfilter_cthelper-1.0.0-9.el7################################# [ 40%]
5:conntrack-tools-1.4.4-4.el7 ################################# [ 50%]
6:kubelet-1.14.1-0 ################################# [ 60%]
7:kubernetes-cni-0.7.5-0 ################################# [ 70%]
8:kubectl-1.14.1-0 ################################# [ 80%]
9:cri-tools-1.12.0-0 ################################# [ 90%]
10:kubeadm-1.14.1-0 ################################# [100%]
Enable bash completion for kubectl.
[root@docker-offline ~]# source <(kubectl completion bash)
[root@docker-offline ~]# kubectl completion bash > /etc/bash_completion.d/kubectl
Import the tar files of docker images into Docker.
[root@docker-offline ~]# docker load < ~/k8s/coredns.tar
fb61a074724d: Loading layer 479.7kB/479.7kB
c6a5fc8a3f01: Loading layer 40.05MB/40.05MB
Loaded image: k8s.gcr.io/coredns:1.3.1
[root@docker-offline ~]# docker load < ~/k8s/kube-proxy.tar
5ba3be777c2d: Loading layer 43.88MB/43.88MB
0b8d2e946c93: Loading layer 3.403MB/3.403MB
8b9a8fc88f0d: Loading layer 36.69MB/36.69MB
Loaded image: k8s.gcr.io/kube-proxy:v1.14.1
[root@docker-offline ~]# docker load < ~/k8s/etcd.tar
8a788232037e: Loading layer 1.37MB/1.37MB
30796113fb51: Loading layer 232MB/232MB
6fbfb277289f: Loading layer 24.98MB/24.98MB
Loaded image: k8s.gcr.io/etcd:3.3.10
[root@docker-offline ~]# docker load < ~/k8s/kube-scheduler.tar
e04ef32df86e: Loading layer 39.26MB/39.26MB
Loaded image: k8s.gcr.io/kube-scheduler:v1.14.1
[root@docker-offline ~]# docker load < ~/k8s/kube-apiserver.tar
97f70f3a7a0c: Loading layer 167.6MB/167.6MB
Loaded image: k8s.gcr.io/kube-apiserver:v1.14.1
[root@docker-offline ~]# docker load < ~/k8s/pause.tar
e17133b79956: Loading layer 744.4kB/744.4kB
Loaded image: k8s.gcr.io/pause:3.1
[root@docker-offline ~]# docker load < ~/k8s/kube-controller-manager.tar
d8ca6e1aa16e: Loading layer 115.6MB/115.6MB
Loaded image: k8s.gcr.io/kube-controller-manager:v1.14.1
Now, we have all the required Docker images in local registry. Therefore, we can configure this CentOS 7 machine either as Kubernetes (K8s) master or worker node.
We don't have configured any master node. Therefore, we have to configure a master node first.
[root@docker-offline ~]# kubeadm init
I0427 20:36:47.088327 18015 version.go:96] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
I0427 20:36:47.090078 18015 version.go:97] falling back to the local client version: v1.14.1
[init] Using Kubernetes version: v1.14.1
[preflight] Running pre-flight checks
[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly
[WARNING Service-Kubelet]: kubelet service is not enabled, please run 'systemctl enable kubelet.service'
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [docker-offline.example.com localhost] and IPs [192.168.116.159 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [docker-offline.example.com localhost] and IPs [192.168.116.159 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [docker-offline.example.com kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.116.159]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 27.538706 seconds
[upload-config] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --experimental-upload-certs
[mark-control-plane] Marking the node docker-offline.example.com as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node docker-offline.example.com as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 6e4ntu.a5r1md9vuqex4pe8
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
Your Kubernetes control-plane has initialized successfully!
To start using your cluster, you need to run the following as a regular user:
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/
Then you can join any number of worker nodes by running the following on each as root:
kubeadm join 192.168.116.159:6443 --token 6e4ntu.a5r1md9vuqex4pe8 \
--discovery-token-ca-cert-hash sha256:19f4d9f6d433cc12addb70e2737c629213777deed28fa5dcc33f9d05d2382d5b
Execute suggested script.
[root@docker-offline ~]# mkdir -p $HOME/.kube
[root@docker-offline ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@docker-offline ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
Start and enable kubelet.service.
[root@docker-offline ~]# systemctl enable kubelet.service
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.
[root@docker-offline ~]# systemctl start kubelet.service
Add Flannel network.
[root@docker-offline ~]# kubectl apply -f ~/k8s/kube-flannel.yml
podsecuritypolicy.extensions/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created
List nodes in Kubernetes (K8s) cluster.
[root@docker-offline ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker-offline.example.com NotReady master 5m9s v1.14.1
We have successfully installed Kubernetes (K8s) offline on CentOS 7.
 Offline on CentOS 7){kind=link}
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