在網上找了好幾種方案 發現大家用的最多的就是k8s 官網的。
比較簡單方便。
https://kubernetes.io/docs/tasks/run-application/run-replicated-stateful-application/?spm=a2c4e.10696291.0.0.3c3919a4hZOvsm
該頁面顯示如何使用StatefulSet 控制器去運行一個有狀態的應用程序。此例是一主多從的 MySQL 集群。
請注意 這不是生產配置。 重點是， MySQL 設置保留在不安全的默認值上，使重點放在 Kubernetes 中運行有狀態應用程序的常規模式。
准備開始
教程目標
- 使用 StatefulSet 控制器部署復制的 MySQL 拓撲。
- 發送 MySQL 客戶端流量。
- 觀察對宕機的抵抗力。
- 縮放 StatefulSet 的大小。
部署 MySQL
部署 MySQL 示例，包含一個 ConfigMap，兩個 Services，與一個 StatefulSet。
ConfigMap
從以下的 YAML 配置文件創建 ConfigMap ：
application/mysql/mysql-configmap.yaml  |
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
labels:
app: mysql
data:
master.cnf: |
# Apply this config only on the master.
[mysqld]
log-bin
slave.cnf: |
# Apply this config only on slaves.
[mysqld]
super-read-only
|
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-configmap.yaml
這個 ConfigMap 提供 my.cnf 覆蓋，使您可以獨立控制 MySQL 主服務器和從服務器的配置。 在這種情況下，您希望主服務器能夠將復制日志提供給從服務器，並且希望從服務器拒絕任何不是通過復制進行的寫操作。
ConfigMap 本身沒有什么特別之處，它可以使不同部分應用於不同的 Pod。 每個 Pod 都會決定在初始化時要看基於 StatefulSet 控制器提供的信息。
Services
從以下 YAML 配置文件創建服務：
application/mysql/mysql-services.yaml |
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
clusterIP: None
selector:
app: mysql
---
# Client service for connecting to any MySQL instance for reads.
# For writes, you must instead connect to the master: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
name: mysql-read
labels:
app: mysql
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql
|
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-services.yaml
Headless Service 給 StatefulSet 控制器為集合中每個 Pod 創建的 DNS 條目提供了一個宿主。因為 Headless Service 名為 mysql，所以可以通過在同一 Kubernetes 集群和 namespace 中的任何其他 Pod 內解析 <pod-name>.mysql 來訪問 Pod。
客戶端 Service 稱為 mysql-read，是一種常規 Service，具有其自己的群集 IP，該群集 IP 在報告為就緒的所有MySQL Pod 中分配連接。可能端點的集合包括 MySQL 主節點和所有從節點。
請注意，只有讀取查詢才能使用負載平衡的客戶端 Service。因為只有一個 MySQL 主服務器，所以客戶端應直接連接到 MySQL 主服務器 Pod (通過其在 Headless Service 中的 DNS 條目)以執行寫入操作。
StatefulSet
最后，從以下 YAML 配置文件創建 StatefulSet：
application/mysql/mysql-statefulset.yaml |
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
serviceName: mysql
replicas: 3
template:
metadata:
labels:
app: mysql
spec:
initContainers:
- name: init-mysql
image: mysql:5.7
command:
- bash
- "-c"
- |
set -ex
# Generate mysql server-id from pod ordinal index.
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
echo [mysqld] > /mnt/conf.d/server-id.cnf
# Add an offset to avoid reserved server-id=0 value.
echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
# Copy appropriate conf.d files from config-map to emptyDir.
if [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/master.cnf /mnt/conf.d/
else
cp /mnt/config-map/slave.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: gcr.io/google-samples/xtrabackup:1.0
command:
- bash
- "-c"
- |
set -ex
# Skip the clone if data already exists.
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Skip the clone on master (ordinal index 0).
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
# Clone data from previous peer.
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# Prepare the backup.
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 500m
memory: 1Gi
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
# Check we can execute queries over TCP (skip-networking is off).
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: gcr.io/google-samples/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# Determine binlog position of cloned data, if any.
if [[ -f xtrabackup_slave_info && "x$(<xtrabackup_slave_info)" != "x" ]]; then
# XtraBackup already generated a partial "CHANGE MASTER TO" query
# because we're cloning from an existing slave. (Need to remove the tailing semicolon!)
cat xtrabackup_slave_info | sed -E 's/;$//g' > change_master_to.sql.in
# Ignore xtrabackup_binlog_info in this case (it's useless).
rm -f xtrabackup_slave_info xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# We're cloning directly from master. Parse binlog position.
[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
rm -f xtrabackup_binlog_info xtrabackup_slave_info
echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
fi
# Check if we need to complete a clone by starting replication.
if [[ -f change_master_to.sql.in ]]; then
echo "Waiting for mysqld to be ready (accepting connections)"
until mysql -h 127.0.0.1 -e "SELECT 1"; do sleep 1; done
echo "Initializing replication from clone position"
mysql -h 127.0.0.1 \
-e "$(<change_master_to.sql.in), \
MASTER_HOST='mysql-0.mysql', \
MASTER_USER='root', \
MASTER_PASSWORD='', \
MASTER_CONNECT_RETRY=10; \
START SLAVE;" || exit 1
# In case of container restart, attempt this at-most-once.
mv change_master_to.sql.in change_master_to.sql.orig
fi
# Start a server to send backups when requested by peers.
exec ncat --listen --keep-open --send-only --max-conns=1 3307 -c \
"xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root"
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
requests:
cpu: 100m
memory: 100Mi
volumes:
- name: conf
emptyDir: {}
- name: config-map
configMap:
name: mysql
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes: ["ReadWriteOnce"]
resources:
requests:
storage: 10Gi
|
kubectl apply -f https://k8s.io/examples/application/mysql/mysql-statefulset.yaml
您可以通過運行以下命令查看啟動進度：
kubectl get pods -l app=mysql --watch
一段時間后，您應該看到所有3個 Pod 都開始運行：
NAME READY STATUS RESTARTS AGE
mysql-0 2/2 Running 0 2m
mysql-1 2/2 Running 0 1m
mysql-2 2/2 Running 0 1m
輸入Ctrl+C取消觀察。 如果您看不到任何進度，確保已啟用前提條件中提到的動態 PersistentVolume 預配器。
