[英]How to use repmgr with dockerized Postgresql?
I'm trying to create Postgresql setup with replication and automatic failover. 我正在尝试使用复制和自动故障转移来创建Postgresql安装程序。 I wanted it to be reusable, scalable and portable, so I tried to use docker to run Postgres.
我希望它可重用,可伸缩且可移植,因此我尝试使用docker运行Postgres。 I also didnt want to reinvent the wheel, so I tried to use repmgr as it is recommended tool when setting up postgres replication.
我也不想重新发明轮子,因此在设置postgres复制时尝试使用repmgr作为推荐工具。
On first machine, I started master node using docker-compose and simple Dockerfile. 在第一台机器上,我使用docker-compose和简单的Dockerfile启动了主节点。 Then I added bash script to run after start of container.
然后我添加了bash脚本以在容器启动后运行。 It looks like master was setup properly.
看来母版已正确设置。
Then on second machine I tried to run standby. 然后在第二台计算机上,我尝试运行待机状态。 I started postgres in docker and experimented.
我在docker中启动了postgres并进行了实验。 As we can read on repmgr github repo , to run standby I need to clone master with repmgr command, which uses pg_basebackup internally.
正如我们可以在repmgr github repo上阅读的那样 ,要运行待机状态,我需要使用repmgr命令克隆master,该命令在内部使用pg_basebackup。 Pg_basebackup wont let me clone db into not-empty directory (pgdata), so I need to remove pgdata created by dockerized postgres before cloning.
Pg_basebackup不会让我将db克隆到非空目录(pgdata)中,因此在克隆之前,我需要删除由dockerized postgres创建的pgdata。 When I do that, container dies, because of course the only service, postgres, dies without its files.
当我这样做时,容器会死掉,因为当然唯一的服务postgres会死掉而没有文件。 So I can not run repmgr command afterwards, because there is no container to run it inside :)
所以我以后不能运行repmgr命令,因为里面没有容器可以运行它:)
So I tried creating another Dockerfile for standbies only. 因此,我尝试仅为备用对象创建另一个Dockerfile。 Inside pgdata is removed, then repmgr clones master, then postgres is started properly.
在内部删除pgdata,然后repmgr克隆master,然后正确启动postgres。 There are no errors.
没有错误。 But when I log into master machine and verify if replication is running - it is not.
但是,当我登录到主计算机并验证复制是否正在运行时,它不是。
Files I used and created: docker-compose.yml (both master and standby node): 我使用和创建的文件:docker-compose.yml(主节点和备用节点):
version: '3'
services:
db:
build:
context: .
volumes:
- ${DATABASE_STORAGE_PATH}:/var/lib/postgresql/data
env_file:
- .env
environment:
- PGDATA=/var/lib/postgresql/data/pgdata
ports:
- ${DB_PORT}:5432
Master Dockerfile: 主Dockerfile:
FROM postgres:9.6.4
# install repmgr
RUN apt-get update \
&& apt-get install -y repmgr
# COPY conf files
COPY repmgr.conf .
COPY postgres.replication.conf /var/lib/postgresql/data/pgdata/
RUN echo "include '/var/lib/postgresql/data/pgdata/postgres.replication.conf'" >> /var/lib/postgresql/data/pgdata/postgresql.conf
CMD ["postgres"]
Bash script to run when postgres container (master) is alive: 当postgres容器(主服务器)处于活动状态时运行的Bash脚本:
#!/bin/bash
CONTAINER_ID="replicatest2_db_1"
docker exec -d $CONTAINER_ID createuser -s repmgr -U postgres
docker exec -d $CONTAINER_ID createdb repmgr -O repmgr -U postgres
docker exec -d $CONTAINER_ID su postgres -c 'repmgr -f repmgr.conf master register'
Standby docker-compose is the same. 备用docker-compose相同。 Standby Dockerfile:
备用Dockerfile:
FROM postgres:9.6.4
# install repmgr
RUN apt-get update \
&& apt-get install -y repmgr
# COPY repmgr conf
COPY repmgr.conf .
RUN rm -rf /var/lib/postgresql/data/pgdata
RUN su postgres -c "repmgr -h {master-host} -p {master-port} -U repmgr -d repmgr -D /var/lib/postgresql/data/pgdata -f repmgr.conf standby clone"
CMD ["postgres"]
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