Replicated stateful application doesn't need its own directory.
This commit is contained in:
Anthony Yeh
@@ -0,0 +1,165 @@
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apiVersion: apps/v1beta1
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kind: StatefulSet
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metadata:
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name: mysql
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spec:
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serviceName: mysql
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replicas: 3
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template:
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metadata:
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labels:
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app: mysql
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annotations:
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pod.beta.kubernetes.io/init-containers: '[
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{
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"name": "init-mysql",
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"image": "mysql:5.7",
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"command": ["bash", "-c", "
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set -ex\n
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# mysqld --initialize expects an empty data dir.\n
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rm -rf /mnt/data/lost+found\n
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# Generate mysql server-id from pod ordinal index.\n
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[[ `hostname` =~ -([0-9]+)$ ]] || exit 1\n
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ordinal=${BASH_REMATCH[1]}\n
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echo [mysqld] > /mnt/conf.d/server-id.cnf\n
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# Add an offset to avoid reserved server-id=0 value.\n
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echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf\n
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# Copy appropriate conf.d files from config-map to emptyDir.\n
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if [[ $ordinal -eq 0 ]]; then\n
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cp /mnt/config-map/master.cnf /mnt/conf.d/\n
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else\n
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cp /mnt/config-map/slave.cnf /mnt/conf.d/\n
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fi\n
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"],
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"volumeMounts": [
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{"name": "data", "mountPath": "/mnt/data"},
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{"name": "conf", "mountPath": "/mnt/conf.d"},
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{"name": "config-map", "mountPath": "/mnt/config-map"}
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]
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},
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{
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"name": "clone-mysql",
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"image": "gcr.io/google-samples/xtrabackup:1.0",
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"command": ["bash", "-c", "
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set -ex\n
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# Skip the clone if data already exists.\n
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[[ -d /var/lib/mysql/mysql ]] && exit 0\n
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# Skip the clone on master (ordinal index 0).\n
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[[ `hostname` =~ -([0-9]+)$ ]] || exit 1\n
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ordinal=${BASH_REMATCH[1]}\n
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[[ $ordinal -eq 0 ]] && exit 0\n
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# Clone data from previous peer.\n
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ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql\n
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# Prepare the backup.\n
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xtrabackup --prepare --target-dir=/var/lib/mysql\n
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"],
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"volumeMounts": [
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{"name": "data", "mountPath": "/var/lib/mysql"},
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{"name": "conf", "mountPath": "/etc/mysql/conf.d"}
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]
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}
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]'
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spec:
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containers:
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- name: mysql
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image: mysql:5.7
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env:
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- name: MYSQL_ALLOW_EMPTY_PASSWORD
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value: "1"
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ports:
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- name: mysql
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containerPort: 3306
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volumeMounts:
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- name: data
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mountPath: /var/lib/mysql
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- name: conf
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mountPath: /etc/mysql/conf.d
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resources:
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requests:
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cpu: 1
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memory: 1Gi
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livenessProbe:
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exec:
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command: ["mysqladmin", "ping"]
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initialDelaySeconds: 30
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timeoutSeconds: 5
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readinessProbe:
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exec:
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# Check we can execute queries over TCP (skip-networking is off).
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command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
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initialDelaySeconds: 5
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timeoutSeconds: 1
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- name: xtrabackup
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image: gcr.io/google-samples/xtrabackup:1.0
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ports:
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- name: xtrabackup
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containerPort: 3307
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command:
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- bash
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- "-c"
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- |
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set -ex
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cd /var/lib/mysql
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# Determine binlog position of cloned data, if any.
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if [[ -f xtrabackup_slave_info ]]; then
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# XtraBackup already generated a partial "CHANGE MASTER TO" query
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# because we're cloning from an existing slave.
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mv xtrabackup_slave_info change_master_to.sql.in
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# Ignore xtrabackup_binlog_info in this case (it's useless).
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rm -f xtrabackup_binlog_info
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elif [[ -f xtrabackup_binlog_info ]]; then
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# We're cloning directly from master. Parse binlog position.
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[[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
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rm xtrabackup_binlog_info
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echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
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MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
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fi
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# Check if we need to complete a clone by starting replication.
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if [[ -f change_master_to.sql.in ]]; then
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echo "Waiting for mysqld to be ready (accepting connections)"
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until mysql -h 127.0.0.1 -e "SELECT 1"; do sleep 1; done
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echo "Initializing replication from clone position"
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# In case of container restart, attempt this at-most-once.
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mv change_master_to.sql.in change_master_to.sql.orig
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mysql -h 127.0.0.1 <<EOF
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$(<change_master_to.sql.orig),
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MASTER_HOST='mysql-0.mysql',
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MASTER_USER='root',
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MASTER_PASSWORD='',
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MASTER_CONNECT_RETRY=10;
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START SLAVE;
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EOF
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fi
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# Start a server to send backups when requested by peers.
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exec ncat --listen --keep-open --send-only --max-conns=1 3307 -c \
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"xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root"
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volumeMounts:
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- name: data
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mountPath: /var/lib/mysql
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- name: conf
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mountPath: /etc/mysql/conf.d
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resources:
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requests:
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cpu: 100m
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memory: 100Mi
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volumes:
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- name: conf
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emptyDir: {}
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- name: config-map
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configMap:
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name: mysql
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volumeClaimTemplates:
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- metadata:
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name: data
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annotations:
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volume.alpha.kubernetes.io/storage-class: default
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spec:
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accessModes: ["ReadWriteOnce"]
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resources:
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requests:
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storage: 10Gi
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