深入浅析Docker容器中的Patroni

目录

• 创建镜像
• 文件结构
• dockerfile
• entrypoint.sh
• function
• generatefile
• 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：

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