Ubuntu 16.04下搭建kubernetes集群环境
简介目前Kubernetes为Ubuntu提供的kube-up脚本，不支持15.10以及16.04这两个使用systemd作为init系统的版本。
这里详细介绍一下如何以非Docker方式在Ubuntu16.04集群上手动安装部署Kubernetes的过程。
手动的部署过程，可以很容易写成自动部署的脚本。同时了解整个部署过程，对深入理解Kubernetes的架构及各功能模块也会很有帮助。
环境信息
版本信息
组件
版本
etcd
2.3.1
Flannel
0.5.5
Kubernetes
1.3.4
主机信息
主机
IP
OS
k8s-master
172.16.203.133
Ubuntu 16.04
k8s-node01
172.16.203.134
Ubuntu 16.04
k8s-node02
172.16.203.135
Ubuntu 16.04
安装Docker
每台主机上安装最新版Docker Engine(目前是1.12) - https://docs.docker.com/engine/installation/linux/ubuntulinux/
部署etcd集群
我们将在3台主机上安装部署etcd集群
下载etcd
在部署机上下载etcd
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ETCD_VERSION=${ETCD_VERSION:-"2.3.1"}
ETCD="etcd-v${ETCD_VERSION}-linux-amd64"
curl -L https://github.com/coreos/etcd/releases/download/v${ETCD_VERSION}/${ETCD}.tar.gz -o etcd.tar.gz
tar xzf etcd.tar.gz -C /tmp
cd /tmp/etcd-v${ETCD_VERSION}-linux-amd64
for h in k8s-master k8s-node01 k8s-node02; do ssh user@$h mkdir -p '$HOME/kube' && scp -r etcd* user@$h:~/kube; done
for h in k8s-master k8s-node01 k8s-node02; do ssh user@$h 'sudo mkdir -p /opt/bin && sudo mv $HOME/kube/* /opt/bin && rm -rf $home/kube/*'; done
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配置etcd服务
在每台主机上，分别创建/opt/config/etcd.conf和/lib/systemd/system/etcd.service文件，（注意修改红色粗体处的IP地址）
/opt/config/etcd.conf
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sudo mkdir -p /var/lib/etcd/
sudo mkdir -p /opt/config/
sudocat <<EOF |sudo tee /opt/config/etcd.conf
ETCD_DATA_DIR=/var/lib/etcd
ETCD_NAME=$(hostname)
ETCD_INITIAL_CLUSTER=master=http://172.16.203.133:2380,node01=http://172.16.203.134:2380,node02=http://172.16.203.135:2380
ETCD_INITIAL_CLUSTER_STATE=new
ETCD_LISTEN_PEER_URLS=http://172.16.203.133:2380
ETCD_INITIAL_ADVERTISE_PEER_URLS=http://172.16.203.133:2380
ETCD_ADVERTISE_CLIENT_URLS=http://172.16.203.133:2379
ETCD_LISTEN_CLIENT_URLS=http://172.16.203.133:2379
GOMAXPROCS=$(nproc)
EOF
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/lib/systemd/system/etcd.service
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Description=Etcd Server
Documentation=https://github.com/coreos/etcd
After=network.target
User=root
Type=simple
EnvironmentFile=-/opt/config/etcd.conf
ExecStart=/opt/bin/etcd
Restart=on-failure
RestartSec=10s
LimitNOFILE=40000
WantedBy=multi-user.target
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然后在每台主机上运行
sudo systemctl daemon-reload sudo systemctl enable etcd
sudo systemctl start etcd
下载Flannel
FLANNEL_VERSION=${FLANNEL_VERSION:-"0.5.5"}
curl -Lhttps://github.com/coreos/flannel/releases/download/v${FLANNEL_VERSION}/flannel-${FLANNEL_VERSION}-linux-amd64.tar.gz flannel.tar.gz
tar xzfflannel.tar.gz -C /tmp
编译K8s
在部署机上编译K8s，需要安装docker engine(1.12)和go(1.6.2)
git clone https://github.com/kubernetes/kubernetes.git
cd kubernetes
make>
tar xzf _output/release-stage/full/kubernetes/server/kubernetes-server-linux-amd64.tar.gz -C /tmp
Note
除了linux/amd64，默认还会为其他平台做交叉编译。为了减少编译时间，可以修改hack/lib/golang.sh，把KUBE_SERVER_PLATFORMS， KUBE_CLIENT_PLATFORMS和KUBE_TEST_PLATFORMS中除linux/amd64以外的其他平台注释掉。
部署K8s Master
复制程序文件
cd /tmp
scp kubernetes/server/bin/kube-apiserver \
kubernetes/server/bin/kube-controller-manager \
kubernetes/server/bin/kube-scheduler kubernetes/server/bin/kubelet kubernetes/server/bin/kube-proxy user@172.16.203.133:~/kube
scp flannel-${FLANNEL_VERSION}/flanneld user@172.16.203.133:~/kube
ssh -t user@172.16.203.133 'sudo mv ~/kube/* /opt/bin/'
创建证书
在master主机上 ，运行如下命令创建证书
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mkdir -p /srv/kubernetes/
cd /srv/kubernetes
export MASTER_IP=172.16.203.133
openssl genrsa -out ca.key 2048
openssl req -x509 -new -nodes -key ca.key -subj "/CN=${MASTER_IP}" -days 10000 -out ca.crt
openssl genrsa -out server.key 2048
openssl req -new -key server.key -subj "/CN=${MASTER_IP}" -out server.csr
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 10000
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配置kube-apiserver服务
我们使用如下的Service以及Flannel的网段：
SERVICE_CLUSTER_IP_RANGE=172.18.0.0/16
FLANNEL_NET=192.168.0.0/16
在master主机上，创建/lib/systemd/system/kube-apiserver.service文件，内容如下
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Description=Kubernetes API Server
Documentation=https://github.com/kubernetes/kubernetes
After=network.target
User=root
ExecStart=/opt/bin/kube-apiserver \
--insecure-bind-address=0.0.0.0 \
--insecure-port=8080 \
--etcd-servers=http://172.16.203.133:2379, http://172.16.203.134:2379, http://172.16.203.135:2379 \
--logtostderr=true \
--allow-privileged=false \
--service-cluster-ip-range=172.18.0.0/16 \
--admission-control=NamespaceLifecycle,LimitRanger,ServiceAccount,SecurityContextDeny,ResourceQuota \
--service-node-port-range=30000-32767 \
--advertise-address=172.16.203.133 \
--client-ca-file=/srv/kubernetes/ca.crt \
--tls-cert-file=/srv/kubernetes/server.crt \
--tls-private-key-file=/srv/kubernetes/server.key
Restart=on-failure
Type=notify
LimitNOFILE=65536
WantedBy=multi-user.target
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配置kube-controller-manager服务
在master主机上，创建/lib/systemd/system/kube-controller-manager.service文件，内容如下
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Description=Kubernetes Controller Manager
Documentation=https://github.com/kubernetes/kubernetes
User=root
ExecStart=/opt/bin/kube-controller-manager \
--master=127.0.0.1:8080 \
--root-ca-file=/srv/kubernetes/ca.crt \
--service-account-private-key-file=/srv/kubernetes/server.key \
--logtostderr=true
Restart=on-failure
LimitNOFILE=65536
WantedBy=multi-user.target
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配置kuber-scheduler服务
在master主机上，创建/lib/systemd/system/kube-scheduler.service文件，内容如下
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Description=Kubernetes Scheduler
Documentation=https://github.com/kubernetes/kubernetes
User=root
ExecStart=/opt/bin/kube-scheduler \
--logtostderr=true \
--master=127.0.0.1:8080
Restart=on-failure
LimitNOFILE=65536
WantedBy=multi-user.target
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配置flanneld服务
在master主机上，创建/lib/systemd/system/flanneld.service文件，内容如下
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Description=Flanneld
Documentation=https://github.com/coreos/flannel
After=network.target
Before=docker.service
User=root
ExecStart=/opt/bin/flanneld \
--etcd-endpoints="http://172.16.203.133:2379,http://172.16.203.134:2379,http://172.16.203.135:2379" \
--iface=172.16.203.133 \
--ip-masq
Restart=on-failure
Type=notify
LimitNOFILE=65536
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启动服务
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/opt/bin/etcdctl --endpoints="http://172.16.203.133:2379,http://172.16.203.134:2379,http://172.16.203.135:2379" mk /coreos.com/network/config \ '{"Network":"192.168.0.0/16", "Backend": {"Type": "vxlan"}}'
sudo systemctl daemon-reload
sudo systemctl enable kube-apiserver
sudo systemctl enable kube-controller-manager
sudo systemctl enable kube-scheduler
sudo systemctl enable flanneld
sudo systemctl start kube-apiserver
sudo systemctl start kube-controller-manager
sudo systemctl start kube-scheduler
sudo systemctl start flanneld
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修改Docker服务
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source /run/flannel/subnet.env
sudo sed -i "s|^ExecStart=/usr/bin/dockerd -H fd://$|ExecStart=/usr/bin/dockerd -H tcp://127.0.0.1:4243 -H unix:///var/run/docker.sock --bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU}|g" /lib/systemd/system/docker.service
rc=0
ip link show docker0 >/dev/null 2>&1 || rc="$?"
if [[ "$rc" -eq "0" ]]; then
ip link set dev docker0 down
ip link delete docker0
fi
sudo systemctl daemon-reload
sudo systemctl enable docker
sudo systemctl restart docker
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部署K8s Node
复制程序文件
cd /tmp
for h in k8s-master k8s-node01 k8s-node02; do scp kubernetes/server/bin/kubelet kubernetes/server/bin/kube-proxy user@$h:~/kube; done
for h in k8s-master k8s-node01 k8s-node02; do scp flannel-${FLANNEL_VERSION}/flanneld user@$h:~/kube;done
for h in k8s-master k8s-node01 k8s-node02; do ssh -t user@$h 'sudo mkdir -p /opt/bin && sudo mv ~/kube/* /opt/bin/'; done
配置Flanned以及修改Docker服务
参见Master部分相关步骤： 配置Flanneld服务，启动Flanneld服务，修改Docker服务。注意修改iface的地址
配置kubelet服务
/lib/systemd/system/kubelet.service，注意修改IP地址
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Description=Kubernetes Kubelet
After=docker.service
Requires=docker.service
ExecStart=/opt/bin/kubelet \
--hostname-override=172.16.203.133 \
--api-servers=http://172.16.203.133:8080 \
--logtostderr=true
Restart=on-failure
KillMode=process
WantedBy=multi-user.target
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启动服务
sudo systemctl daemon-reload
sudo systemctl enable kubelet
sudo systemctl start kubelet
配置kube-proxy服务
/lib/systemd/system/kube-proxy.service，注意修改IP地址
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Description=Kubernetes Proxy
After=network.target
ExecStart=/opt/bin/kube-proxy\
--hostname-override=172.16.203.133 \
--master=http://172.16.203.133:8080 \
--logtostderr=true
Restart=on-failure
WantedBy=multi-user.target
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启动服务
sudo systemctl daemon-reload
sudo systemctl enable kube-proxy
sudo systemctl start kube-proxy
配置验证K8s
生成配置文件
在部署机上运行
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KUBE_USER=admin
KUBE_PASSWORD=$(python -c 'import string,random; print("".join(random.SystemRandom().choice(string.ascii_letters + string.digits) for _ in range(16)))')
DEFAULT_KUBECONFIG="${HOME}/.kube/config"
mkdir -p $(dirname "${KUBECONFIG}")
touch "${KUBECONFIG}"
CONTEXT=ubuntu
KUBECONFIG=${KUBECONFIG:-$DEFAULT_KUBECONFIG}
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-cluster "${CONTEXT}" --server=http://172.16.203.133:8080 --insecure-skip-tls-verify=true
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-credentials "${CONTEXT}" --username=${KUBE_USER} --password=${KUBE_PASSWORD}
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-context "${CONTEXT}" --cluster="${CONTEXT}" --user="${CONTEXT}"
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config use-context "${CONTEXT}"--cluster="${CONTEXT}"
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验证
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$ kubectl get nodes
NAME STATUS AGE
172.16.203.133 Ready 2h
172.16.203.134 Ready 2h
172.16.203.135 Ready 2h
$cat <<EOF > nginx.yml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: my-nginx
spec:
replicas: 2
template:
metadata:
labels:
run: my-nginx
spec:
containers:
- name: my-nginx
image: nginx
ports:
- containerPort: 80
EOF
$kubectl create -f nginx.yml
$kubectl get pods -l run=my-nginx -o wide
NAME READY STATUS RESTARTS AGE IP NODE
my-nginx-1636613490-9ibg1 1/1 Running 0 13m 192.168.31.2 172.16.203.134
my-nginx-1636613490-erx98 1/1 Running 0 13m 192.168.56.3 172.16.203.133
$kubectl expose deployment/my-nginx
$kubectl get service my-nginx
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-nginx 172.18.28.48 <none> 80/TCP 37s
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在三台主机上访问pod或者service的IP地址，都可以访问到nginx服务
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$ curl http://172.18.28.48
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
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用户认证和安全
我们在最后一步生成kube配置文件的时候，创建了用户名和密码，但并没在apiserver上启用（使用--basic-auth-file参数），也就是说，只要能访问到172.16.203.133:8080，就可以操作k8s集群。如果是内部系统，并且配置好访问规则，也是可以接受的
为了增强安全性，可以启用证书认证，有两种方式：同时启用minion和客户端与master之间的认证，或者只启用客户端与master之间的证书认证。
minion节点的证书生成和配置可以参考http://kubernetes.io/docs/getting-started-guides/scratch/#security-models以及http://kubernetes.io/docs/getting-started-guides/ubuntu-calico/的相关部分。
这里我们看一下如何启用客户端与master之间的证书认证。使用这种方式也相对安全，minion节点和master一般在同一个数据中心，可以把对HTTP 8080的访问限制在数据中心内部，而客户端只能使用证书通过HTTPS访问api server。
创建客户端证书
在master主机上运行如下命令
cd /srv/kubernetes
export CLINET_IP=172.16.203.1
openssl genrsa -out client.key 2048
openssl req -new -key client.key -subj "/CN=${CLINET_IP}" -out client.csr
openssl x509 -req -in client.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out client.crt -days 10000
把client.crt和client.key复制到部署机，然后运如下命令，生成kube配置文件
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DEFAULT_KUBECONFIG="${HOME}/.kube/config"
mkdir -p $(dirname "${KUBECONFIG}")
touch "${KUBECONFIG}"
CONTEXT=ubuntu
KUBECONFIG=${KUBECONFIG:-$DEFAULT_KUBECONFIG}
KUBE_CERT=client.crt
KUBE_KEY=client.key
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-cluster "${CONTEXT}" --server=https://172.16.203.133:6443 --insecure-skip-tls-verify=true
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-credentials "${CONTEXT}" --client-certificate=${KUBE_CERT} --client-key=${KUBE_KEY} --embed-certs=true
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config set-context "${CONTEXT}" --cluster="${CONTEXT}" --user="${CONTEXT}"
KUBECONFIG="${KUBECONFIG}" /tmp/kubernetes/server/bin/kubectl config use-context "${CONTEXT}"--cluster="${CONTEXT}"
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部署附件组件
部署DNS
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DNS_SERVER_IP="172.18.8.8"
DNS_DOMAIN="cluster.local"
DNS_REPLICAS=1
KUBE_APISERVER_URL=http://172.16.203.133:8080
cat <<EOF > skydns.yml
apiVersion: v1
kind: ReplicationController
metadata:
name: kube-dns-v17.1
namespace: kube-system
labels:
k8s-app: kube-dns
version: v17.1
kubernetes.io/cluster-service: "true"
spec:
replicas: $DNS_REPLICAS
selector:
k8s-app: kube-dns
version: v17.1
template:
metadata:
labels:
k8s-app: kube-dns
version: v17.1
kubernetes.io/cluster-service: "true"
spec:
containers:
- name: kubedns
image: gcr.io/google_containers/kubedns-amd64:1.5
resources:
# TODO: Set memory limits when we've profiled the container for large
# clusters, then set request = limit to keep this container in
# guaranteed> # "burstable" category so the kubelet doesn't backoff from restarting it.
limits:
cpu: 100m
memory: 170Mi
requests:
cpu: 100m
memory: 70Mi
livenessProbe:
httpGet:
path: /healthz
port: 8080
scheme: HTTP
initialDelaySeconds: 60
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 5
readinessProbe:
httpGet:
path: /readiness
port: 8081
scheme: HTTP
# we poll on pod startup for the Kubernetes master service and
# only setup the /readiness HTTP server once that's available.
initialDelaySeconds: 30
timeoutSeconds: 5
args:
# command = "/kube-dns"
- --domain=$DNS_DOMAIN.
- --dns-port=10053
- --kube-master-url=$KUBE_APISERVER_URL
ports:
- containerPort: 10053
name: dns-local
protocol: UDP
- containerPort: 10053
name: dns-tcp-local
protocol: TCP
- name: dnsmasq
image: gcr.io/google_containers/kube-dnsmasq-amd64:1.3
args:
- --cache-size=1000
- --no-resolv
- --server=127.0.0.1#10053
ports:
- containerPort: 53
name: dns
protocol: UDP
- containerPort: 53
name: dns-tcp
protocol: TCP
- name: healthz
image: gcr.io/google_containers/exechealthz-amd64:1.1
resources:
# keep request = limit to keep this container in guaranteed> limits:
cpu: 10m
memory: 50Mi
requests:
cpu: 10m
# Note that this container shouldn't really need 50Mi of memory. The
# limits are set higher than expected pending investigation on #29688.
# The extra memory was stolen from the kubedns container to keep the
# net memory requested by the pod constant.
memory: 50Mi
args:
- -cmd=nslookup kubernetes.default.svc.$DNS_DOMAIN 127.0.0.1 >/dev/null
- -port=8080
- -quiet
ports:
- containerPort: 8080
protocol: TCP
dnsPolicy: Default# Don't use cluster DNS.
---
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: "KubeDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: $DNS_SERVER_IP
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
EOF
kubectl create -f skydns.yml
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然后，修该各节点的kubelet.service,添加--cluster-dns=172.18.8.8以及--cluster-domain=cluster.local
部署Dashboard
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echo <<'EOF' > kube-dashboard.yml
kind: Deployment
apiVersion: extensions/v1beta1
metadata:
labels:
app: kubernetes-dashboard
version: v1.1.0
name: kubernetes-dashboard
namespace: kube-system
spec:
replicas: 1
selector:
matchLabels:
app: kubernetes-dashboard
template:
metadata:
labels:
app: kubernetes-dashboard
spec:
containers:
- name: kubernetes-dashboard
image: gcr.io/google_containers/kubernetes-dashboard-amd64:v1.1.0
imagePullPolicy: Always
ports:
- containerPort: 9090
protocol: TCP
args:
- --apiserver-host=http://172.16.203.133:8080
livenessProbe:
httpGet:
path: /
port: 9090
initialDelaySeconds: 30
timeoutSeconds: 30
---
kind: Service
apiVersion: v1
metadata:
labels:
app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kube-system
spec:
type: ClusterIP
ports:
- port: 80
targetPort: 9090
selector:
app: kubernetes-dashboard
EOF
kubectl create -f kube-dashboard.yml
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