问题
我想在 k8s 上使用 xtrabackup 进行 mysql 8.0.28 复制。 基于工作正常的 k8s 官方示例（我将在本文稍后讨论），我为 mysql 8.0.28 复制创建了 k8s 集群（注意官方示例中的 mysql 为 5.7），但不起作用。我的yaml文件是
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: mysql-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-pv
spec:
capacity:
storage: 5Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: mysql-sc
local:
path: /tmp
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- controlplane
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-pv-2
spec:
capacity:
storage: 5Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: mysql-sc
local:
path: /tmp
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- node01
---
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
labels:
app: mysql
app.kubernetes.io/name: mysql
data:
my.cnf: |
[mysqld]
!includedir /etc/mysql/conf.d/
primary.cnf: |
# Apply this config only on the primary.
[mysqld]
log-bin
gtid_mode=ON
enforce_gtid_consistency=ON
replica.cnf: |
# Apply this config only on replicas.
[mysqld]
gtid_mode=ON
enforce_gtid_consistency=ON
super-read-only
log_bin=OFF
---
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
app: mysql
app.kubernetes.io/name: 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 primary: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
name: mysql-read
labels:
app: mysql
app.kubernetes.io/name: mysql
readonly: "true"
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
app.kubernetes.io/name: mysql
serviceName: mysql
replicas: 2
template:
metadata:
labels:
app: mysql
app.kubernetes.io/name: mysql
spec:
initContainers:
- name: init-mysql
image: mysql:8.0.28
command:
- bash
- "-c"
- |
set -ex
# Generate mysql server-id from pod ordinal index.
[[ `uname -n` =~ -([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 my.cnf file from config-map to conf-2 volume(emptyDir).
cp /mnt/config-map/my.cnf /mnt/conf-2/
# Copy appropriate conf.d files from config-map to emptyDir.
if [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/primary.cnf /mnt/conf.d/
else
cp /mnt/config-map/replica.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: conf-2
mountPath: /mnt/conf-2
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: hiroaki2020/dtuj_xtrabackup:1.0
securityContext:
runAsUser: 0
runAsGroup: 0
command:
- bash
- "-c"
- |
set -ex
# Skip the clone if data already exists.
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Skip the clone on primary (ordinal index 0).
[[ `uname -n` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
# Clone data from previous peer.
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# Prepare the backup.
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
- name: conf-2
mountPath: /etc/mysql
containers:
- name: mysql
image: mysql:8.0.28
resources:
limits:
memory: 512Mi
cpu: 500m
requests:
memory: 128Mi
cpu: 100m
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
# Check we can execute queries over TCP (skip-networking is off).
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: hiroaki2020/dtuj_xtrabackup:1.0
securityContext:
runAsUser: 0
runAsGroup: 0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# Determine binlog position of cloned data, if any.
if [[ -f xtrabackup_slave_info && "x$(<xtrabackup_slave_info)" != "x" ]]; then
# XtraBackup already generated a partial "CHANGE MASTER TO" query
# because we're cloning from an existing replica. (Need to remove the tailing semicolon!)
cat xtrabackup_slave_info | sed -E 's/;$//g' > change_master_to.sql.in
# Ignore xtrabackup_binlog_info in this case (it's useless).
rm -f xtrabackup_slave_info xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# We're cloning directly from primary. Parse binlog position.
[[ `cat xtrabackup_binlog_info` =~ ^([^.]*\.[0-9]+)[[:space:]]+([0-9]+) ]] || exit 1
rm -f xtrabackup_binlog_info xtrabackup_slave_info
echo "CHANGE MASTER TO MASTER_LOG_FILE='${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
- name: conf-2
mountPath: /etc/mysql
resources:
limits:
cpu: 500m
memory: 512Mi
requests:
cpu: 100m
memory: 100Mi
volumes:
- name: conf
emptyDir: {}
- name: conf-2
emptyDir: {}
- name: config-map
configMap:
name: mysql
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes: ["ReadWriteOnce"]
storageClassName: mysql-sc
resources:
requests:
storage: 5Gi
在上面的 yaml 文件中，我更改了 mysql 映像版本，并根据下面的 Dockerfile 使用名为“hiroaki2020/dtuj_xtrabackup:1.0”的原始映像。
FROM percona/percona-xtrabackup:8.0.28
LABEL maintainer="hiroaki"
RUN microdnf update && \
rm -rf /var/cache/yum && \
microdnf -y install nmap-ncat shadow-utils && \
groupadd --system -g 27 mysql && \
useradd --system -s /usr/bin/false -g mysql -u 27 -c mysql --no-create-home --home-dir /nonexistent mysql && \
microdnf -y remove shadow-utils && \
microdnf clean all
USER mysql
该镜像基于xtrabackup镜像，其版本对应mysql版本（=8.0.28）。我还添加了 ncat cmd 并将用户更改为 mysql，但为了简单起见，通过设置 securityContext 在 k8s 清单 yaml 文件中将其更改回 root。
我在killercoda k8s Playground中应用了上面的k8s清单文件，但是当第二个mysql pod（= mysql-1）启动时，更准确地说，当clone-mysql容器在第二个pod中工作时，第一个mysql pod中的xtrabackup容器得到错误就像
Ncat: assertion failed: count <= INT_MAX QUITTING.
我该如何解决这个问题？
k8s 官方示例，运行良好
正如我所说，上面的清单文件基于 k8s 官方示例。在这个例子中，我在 k8s 上成功运行了 mysql 复制容器，但 mysql 版本是 5.7。比较可能有助于解决问题，因此我提供了此示例的简单步骤。
步骤1
打开killercoda k8s Playground并登录。上面的k8s官方示例链接中有它的链接。这个官方示例可能适用于本地 PC 上的其他 Playground 或 k8s，例如 minikube，但我不确定。
步骤2
vim k8s.yaml
并粘贴此。
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: mysql-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-pv
spec:
capacity:
storage: 1Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: mysql-sc
local:
path: /tmp
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- controlplane
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: mysql-pv-2
spec:
capacity:
storage: 1Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: mysql-sc
local:
path: /tmp
nodeAffinity:
required:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/hostname
operator: In
values:
- node01
---
apiVersion: v1
kind: ConfigMap
metadata:
name: mysql
labels:
app: mysql
app.kubernetes.io/name: mysql
data:
primary.cnf: |
# Apply this config only on the primary.
[mysqld]
log-bin
replica.cnf: |
# Apply this config only on replicas.
[mysqld]
super-read-only
---
# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
name: mysql
labels:
app: mysql
app.kubernetes.io/name: 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 primary: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
name: mysql-read
labels:
app: mysql
app.kubernetes.io/name: mysql
readonly: "true"
spec:
ports:
- name: mysql
port: 3306
selector:
app: mysql
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: mysql
spec:
selector:
matchLabels:
app: mysql
app.kubernetes.io/name: mysql
serviceName: mysql
replicas: 2
template:
metadata:
labels:
app: mysql
app.kubernetes.io/name: mysql
spec:
initContainers:
- name: init-mysql
image: mysql:5.7
command:
- bash
- "-c"
- |
set -ex
# Generate mysql server-id from pod ordinal index.
[[ `uname -n` =~ -([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 [[ $ordinal -eq 0 ]]; then
cp /mnt/config-map/primary.cnf /mnt/conf.d/
else
cp /mnt/config-map/replica.cnf /mnt/conf.d/
fi
volumeMounts:
- name: conf
mountPath: /mnt/conf.d
- name: config-map
mountPath: /mnt/config-map
- name: clone-mysql
image: gcr.io/google-samples/xtrabackup:1.0
command:
- bash
- "-c"
- |
set -ex
# Skip the clone if data already exists.
[[ -d /var/lib/mysql/mysql ]] && exit 0
# Skip the clone on primary (ordinal index 0).
[[ `hostname` =~ -([0-9]+)$ ]] || exit 1
ordinal=${BASH_REMATCH[1]}
[[ $ordinal -eq 0 ]] && exit 0
# Clone data from previous peer.
ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
# Prepare the backup.
xtrabackup --prepare --target-dir=/var/lib/mysql
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
containers:
- name: mysql
image: mysql:5.7
resources:
limits:
memory: 512Mi
cpu: 300m
requests:
memory: 64Mi
cpu: 50m
env:
- name: MYSQL_ALLOW_EMPTY_PASSWORD
value: "1"
ports:
- name: mysql
containerPort: 3306
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
livenessProbe:
exec:
command: ["mysqladmin", "ping"]
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
readinessProbe:
exec:
# Check we can execute queries over TCP (skip-networking is off).
command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
initialDelaySeconds: 5
periodSeconds: 2
timeoutSeconds: 1
- name: xtrabackup
image: gcr.io/google-samples/xtrabackup:1.0
ports:
- name: xtrabackup
containerPort: 3307
command:
- bash
- "-c"
- |
set -ex
cd /var/lib/mysql
# Determine binlog position of cloned data, if any.
if [[ -f xtrabackup_slave_info && "x$(<xtrabackup_slave_info)" != "x" ]]; then
# XtraBackup already generated a partial "CHANGE MASTER TO" query
# because we're cloning from an existing replica. (Need to remove the tailing semicolon!)
cat xtrabackup_slave_info | sed -E 's/;$//g' > change_master_to.sql.in
# Ignore xtrabackup_binlog_info in this case (it's useless).
rm -f xtrabackup_slave_info xtrabackup_binlog_info
elif [[ -f xtrabackup_binlog_info ]]; then
# We're cloning directly from primary. Parse binlog position.
[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || 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 "$(<change_master_to.sql.in), \
MASTER_HOST='mysql-0.mysql', \
MASTER_USER='root', \
MASTER_PASSWORD='', \
MASTER_CONNECT_RETRY=10; \
START SLAVE;" || exit 1
# In case of container restart, attempt this at-most-once.
mv change_master_to.sql.in change_master_to.sql.orig
fi
# Start a server to send backups when requested by peers.
exec ncat --listen --keep-open --send-only --max-conns=1 3307 -c \
"xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root"
volumeMounts:
- name: data
mountPath: /var/lib/mysql
subPath: mysql
- name: conf
mountPath: /etc/mysql/conf.d
resources:
limits:
cpu: 300m
memory: 512Mi
requests:
cpu: 100m
memory: 100Mi
volumes:
- name: conf
emptyDir: {}
- name: config-map
configMap:
name: mysql
volumeClaimTemplates:
- metadata:
name: data
spec:
accessModes: ["ReadWriteOnce"]
storageClassName: mysql-sc
resources:
requests:
storage: 1Gi
我创建了本地持久卷和存储类，并对官方示例进行了轻微更改以使其工作，例如将脚本中的“hostname”cmd 更改为“uname -n”等。
步骤3
奔跑
kubectl apply -f k8s.yaml
完成。等到 pod 准备好后，进入 mysql-0 pod 中的 mysql 容器，并使用 mysql 客户端添加一些记录。您可以看到数据已正确复制到副本服务器。
我将k8s平台从killercoda游乐场切换到minikube，并将ncat更改为最新版本，并增加了对mysql容器的资源分配，现在mysql集群可以正常工作了。
对于使用镜像 percona/percona-xtrabackup:8.0.28 (或 8.0.31) 的用户，可以将 ncat 命令替换为 socat 命令，如下所示来创建服务器：
exec socat TCP-LISTEN:3307,fork,reuseaddr,max-children=1,keepalive \
SYSTEM:"xtrabackup --backup --slave-info --stream=xbstream \
--host=127.0.0.1 --user=root --password=${MYSQL_ROOT_PASSWORD}",pty,raw,echo=0
和用于克隆数据容器的客户端命令
socat TCP:mysql-$((${ordinal}-1)).mysql:3307 EXEC:"xbstream -x -C ${mysqldir}"