深入浅析Docker容器中的Patroni

目录创建镜像文件结构DockerFileentrypoint.shfunctiongeneratefile构建镜像运行镜像总结附图

上一篇文章向大家介绍了Repmgr的搭建过程，实现了自动切换，今天将向大家介绍，如何搭建容器下的Patroni集群环境，Patroni作为开箱即用PG高可用工具，越来越多的被各个厂商用于云环境下使用。

patroni基本架构如图所示：

etcd作为分布式注册中心、进行集群选主工作；vip-manager为主节点设置漂移IP；patroni负责引导集群的创建、运行和管理工作，并可以使用patronictl来进行终端访问。

具体流程：

1、首先启动etcd集群，本例中etcd数量为3个。

2、检测etcd集群状态健康后，启动patroni并竞争选主，其他跟随节点进行数据同步过程。

3、启动vip-manager，通过访问etcd集群中/ S E R V I C E N A M E / {SERVICE_NAME}/ SERVICEN​AME/{CLUSTER_NAME}/leader键中的具体值，判断当前节点是否为主节点ip，如果是则为该节点设置vip，提供对外读写服务。

注：建议真实环境下将etcd部署到独立容器上，对外提供服务。

创建镜像

文件结构

其中Dockerfile为镜像主文件，docker服务通过该文件在本地仓库创建镜像；entrypoint.sh为容器入口文件，负责业务逻辑的处理；function为执行业务方法的入口文件，负责启动etcd，监控etcd集群状态、启动patroni和vip-manager；generatefile为整个容器生成对应的配置文件，包括etcd、patroni及vip-mananger。

目录结构大致如图所示：

注：数据库安装包和patroni安装包请自行构建。

DockerFile

FROM centos:7 MAINTAINER wangzhibin <wangzhibin> ENV USER=”postgresql” PASSWORD=123456 GROUP=postgresql RUN useradd ${USER} && chown -R ${USER}:${GROUP} /home/${USER} && yum -y update && yum install -y iptables sudo net-tools iproute openssh-server openssh-clients which vim sudo crontabs #安装etcd COPY etcd/etcd /usr/sbin COPY etcd/etcdctl /usr/sbin #安装database COPY lib/ /home/${USER}/lib COPY include/ /home/${USER}/include COPY share/ /home/${USER}/share COPY bin/ /home/${USER}/bin/ COPY patroni/ /home/${USER}/patroni #安装vip-manager COPY vip-manager/vip-manager /usr/sbin #安装执行脚本 COPY runtime/ /home/${USER}/runtime COPY entrypoint.sh /sbin/entrypoint.sh #设置环境变量 ENV LD_LIBRARY_PATH /home/${USER}/lib ENV PATH /home/${USER}/bin:$PATH ENV ETCDCTL_API=3 #安装Patroni RUN yum -y install epel-release python-devel && yum -y install python-pip && pip install /home/${USER}/patroni/1/pip-20.3.3.tar.gz && pip install /home/${USER}/patroni/1/psycopg2-2.8.6-cp27-cp27mu-linux_x86_64.whl && pip install –no-index –find-links=/home/${USER}/patroni/2/ -r /home/${USER}/patroni/2/requirements.txt && pip install /home/${USER}/patroni/3/patroni-2.0.1-py2-none-any.whl #修改执行权限 RUN chmod 755 /sbin/entrypoint.sh && mkdir /home/${USER}/etcddata && chown -R ${USER}:${GROUP} /home/${USER} && echo root:root123456 | chpasswd && chmod 755 /sbin/etcd && chmod 755 /sbin/etcdctl && chmod 755 /sbin/vip-manager #设置Sudo RUN chmod 777 /etc/sudoers && sed -i /## Allow root to run any commands anywhere/a ${USER} ALL=(ALL) NOPASSWD:ALL /etc/sudoers && chmod 440 /etc/sudoers #切换用户 USER ${USER} #切换工作目录 WORKDIR /home/${USER} #启动入口程序 CMD [“/bin/bash”, “/sbin/entrypoint.sh”]

entrypoint.sh

#!/bin/bash set -e # shellcheck source=runtime/functions source “/home/${USER}/runtime/function” configure_patroni

function

#!/bin/bash set -e source /home/${USER}/runtime/env-defaults source /home/${USER}/runtime/generatefile PG_DATADIR=/home/${USER}/pgdata PG_BINDIR=/home/${USER}/bin configure_patroni() { #生成配置文件 generate_etcd_conf generate_patroni_conf generate_vip_conf #启动etcd etcdcount=${ETCD_COUNT} count=0 ip_temp=”” array=(${HOSTLIST//,/ }) for host in ${array[@]} do ip_temp+=”http://${host}:2380,” done etcd –config-file=/home/${USER}/etcd.yml >/home/${USER}/etcddata/etcd.log 2>&1 & while [ $count -lt $etcdcount ] do line=(`etcdctl –endpoints=${ip_temp%?} endpoint health -w json`) count=`echo $line | awk -F””health”:true” {print NF-1}` echo “waiting etcd cluster” sleep 5 done #启动patroni patroni /home/${USER}/postgresql.yml > /home/${USER}/patroni/patroni.log 2>&1 & #启动vip-manager sudo vip-manager –config /home/${USER}/vip.yml }

generatefile

#!/bin/bash set -e HOSTNAME=”`hostname`” hostip=`ping ${HOSTNAME} -c 1 -w 1 | sed 1{s/[^(]*(//;s/).*//;q}` #generate etcd generate_etcd_conf() { echo “name : ${HOSTNAME}” >> /home/${USER}/etcd.yml echo “data-dir: /home/${USER}/etcddata” >> /home/${USER}/etcd.yml echo “listen-client-urls: http://0.0.0.0:2379” >> /home/${USER}/etcd.yml echo “advertise-client-urls: http://${hostip}:2379” >> /home/${USER}/etcd.yml echo “listen-peer-urls: http://0.0.0.0:2380” >> /home/${USER}/etcd.yml echo “initial-advertise-peer-urls: http://${hostip}:2380″ >> /home/${USER}/etcd.yml ip_temp=”initial-cluster: ” array=(${HOSTLIST//,/ }) for host in ${array[@]} do ip_temp+=”${host}=http://${host}:2380,” done echo ${ip_temp%?} >> /home/${USER}/etcd.yml echo “initial-cluster-token: etcd-cluster-token” >> /home/${USER}/etcd.yml echo “initial-cluster-state: new” >> /home/${USER}/etcd.yml } #generate patroni generate_patroni_conf() { echo “scope: ${CLUSTER_NAME}” >> /home/${USER}/postgresql.yml echo “namespace: /${SERVICE_NAME}/ ” >> /home/${USER}/postgresql.yml echo “name: ${HOSTNAME} ” >> /home/${USER}/postgresql.yml echo “restapi: ” >> /home/${USER}/postgresql.yml echo ” listen: ${hostip}:8008 ” >> /home/${USER}/postgresql.yml echo ” connect_address: ${hostip}:8008 ” >> /home/${USER}/postgresql.yml echo “etcd: ” >> /home/${USER}/postgresql.yml echo ” host: ${hostip}:2379 ” >> /home/${USER}/postgresql.yml echo ” username: ${ETCD_USER} ” >> /home/${USER}/postgresql.yml echo ” password: ${ETCD_PASSWD} ” >> /home/${USER}/postgresql.yml echo “bootstrap: ” >> /home/${USER}/postgresql.yml echo ” dcs: ” >> /home/${USER}/postgresql.yml echo ” ttl: 30 ” >> /home/${USER}/postgresql.yml echo ” loop_wait: 10 ” >> /home/${USER}/postgresql.yml echo ” retry_timeout: 10 ” >> /home/${USER}/postgresql.yml echo ” maximum_lag_on_failover: 1048576 ” >> /home/${USER}/postgresql.yml echo ” postgresql: ” >> /home/${USER}/postgresql.yml echo ” use_pg_rewind: true ” >> /home/${USER}/postgresql.yml echo ” use_slots: true ” >> /home/${USER}/postgresql.yml echo ” parameters: ” >> /home/${USER}/postgresql.yml echo ” initdb: ” >> /home/${USER}/postgresql.yml echo ” – encoding: UTF8 ” >> /home/${USER}/postgresql.yml echo ” – data-checksums ” >> /home/${USER}/postgresql.yml echo ” pg_hba: ” >> /home/${USER}/postgresql.yml echo ” – host replication ${USER} 0.0.0.0/0 md5 ” >> /home/${USER}/postgresql.yml echo ” – host all all 0.0.0.0/0 md5 ” >> /home/${USER}/postgresql.yml echo “postgresql: ” >> /home/${USER}/postgresql.yml echo ” listen: 0.0.0.0:5432 ” >> /home/${USER}/postgresql.yml echo ” connect_address: ${hostip}:5432 ” >> /home/${USER}/postgresql.yml echo ” data_dir: ${PG_DATADIR} ” >> /home/${USER}/postgresql.yml echo ” bin_dir: ${PG_BINDIR} ” >> /home/${USER}/postgresql.yml echo ” pgpass: /tmp/pgpass ” >> /home/${USER}/postgresql.yml echo ” authentication: ” >> /home/${USER}/postgresql.yml echo ” replication: ” >> /home/${USER}/postgresql.yml echo ” username: ${USER} ” >> /home/${USER}/postgresql.yml echo ” password: ${PASSWD} ” >> /home/${USER}/postgresql.yml echo ” superuser: ” >> /home/${USER}/postgresql.yml echo ” username: ${USER} ” >> /home/${USER}/postgresql.yml echo ” password: ${PASSWD} ” >> /home/${USER}/postgresql.yml echo ” rewind: ” >> /home/${USER}/postgresql.yml echo ” username: ${USER} ” >> /home/${USER}/postgresql.yml echo ” password: ${PASSWD} ” >> /home/${USER}/postgresql.yml echo ” parameters: ” >> /home/${USER}/postgresql.yml echo ” unix_socket_directories: . ” >> /home/${USER}/postgresql.yml echo ” wal_level: hot_standby ” >> /home/${USER}/postgresql.yml echo ” max_wal_senders: 10 ” >> /home/${USER}/postgresql.yml echo ” max_replication_slots: 10 ” >> /home/${USER}/postgresql.yml echo “tags: ” >> /home/${USER}/postgresql.yml echo ” nofailover: false ” >> /home/${USER}/postgresql.yml echo ” noloadbalance: false ” >> /home/${USER}/postgresql.yml echo ” clonefrom: false ” >> /home/${USER}/postgresql.yml echo ” nosync: false ” >> /home/${USER}/postgresql.yml } #…….. 省略部分内容

构建镜像

docker build -t patroni .

运行镜像

运行容器节点1：

docker run –privileged –name patroni1 -itd –hostname patroni1 –net my_net3 –restart always –env ‘CLUSTER_NAME=patronicluster –env ‘SERVICE_NAME=service –env ‘ETCD_USER=etcduser –env ‘ETCD_PASSWD=etcdpasswd –env ‘PASSWD=zalando –env ‘HOSTLIST=patroni1,patroni2,patroni3 –env ‘VIP=172.22.1.88 –env ‘NET_DEVICE=eth0 –env ‘ETCD_COUNT=3 patroni

运行容器节点2：

docker run –privileged –name patroni2 -itd –hostname patroni2 –net my_net3 –restart always –env ‘CLUSTER_NAME=patronicluster –env ‘SERVICE_NAME=service –env ‘ETCD_USER=etcduser –env ‘ETCD_PASSWD=etcdpasswd –env ‘PASSWD=zalando –env ‘HOSTLIST=patroni1,patroni2,patroni3 –env ‘VIP=172.22.1.88 –env ‘NET_DEVICE=eth0 –env ‘ETCD_COUNT=3 patroni

运行容器节点3：docker run –privileged –name patroni3 -itd –hostname patroni3 –net my_net3 –restart always –env ‘CLUSTER_NAME=patronicluster –env ‘SERVICE_NAME=service –env ‘ETCD_USER=etcduser –env ‘ETCD_PASSWD=etcdpasswd –env ‘PASSWD=zalando –env ‘HOSTLIST=patroni1,patroni2,patroni3 –env ‘VIP=172.22.1.88 –env ‘NET_DEVICE=eth0 –env ‘ETCD_COUNT=3 patroni

总结

本操作过程仅限于试验环境，为了演示etcd+patroni+vipmanager整体的容器化搭建。在真实环境下，etcd应该部署在不同容器下，形成独立的分布式集群，并且PG的存储应该映射到本地磁盘或网络磁盘，另外容器集群的搭建尽量使用编排工具，例如docker-compose、docker-warm或者Kubernetes等。

附图

etcd集群状态如图：

patroni集群状态如图：

vip-manager状态如图：