how to promote master, after failover on postgresql with docker

Question

first of all i'm using this setup postgres-docker-cluster, everything works fine during the fail-over, i stop the master and the slave1 take its place, but if i turn the master back on im not sure how to promoted to master again, i would appreciated any pointers on the right direction, do i need to manually promote it? sorry i'm pretty new at this concept(ha). This docker uses repmgr, pgpool2 and postgre 9.5.

some info on the docker

• postgresql-cluster-pgsql
• postgresql-cluster-pgpool
• docker-compose.yml

Answer 1

So i figure out how to sort of solve the problem,

1. Create the containers manually

   Master docker run \ -e INITIAL_NODE_TYPE='master' \ -e NODE_ID=1 \ -e NODE_NAME='node1' \ -e CLUSTER_NODE_NETWORK_NAME='pgmaster' \ -e POSTGRES_PASSWORD='monkey_pass' \ -e POSTGRES_USER='monkey_user' \ -e POSTGRES_DB='monkey_db' \ -e CLUSTER_NODE_REGISTER_DELAY=5 \ -e REPLICATION_DAEMON_START_DELAY=120 \ -e CLUSTER_NAME='pg_cluster' \ -e REPLICATION_DB='replication_db' \ -e REPLICATION_USER='replication_user' \ -e REPLICATION_PASSWORD='replication_pass' \ -v cluster-archives:/var/cluster_archive \ -p 5432:5432 \ --net mynet \ --net-alias pgmaster \ --name pgmastertest \ paunin/postgresql-cluster-pgsql

   Slave docker run \ -e INITIAL_NODE_TYPE='standby' \ -e NODE_ID=2 \ -e NODE_NAME='node2' \ -e REPLICATION_PRIMARY_HOST='pgmaster' \ -e CLUSTER_NODE_NETWORK_NAME='pgslave1' \ -e REPLICATION_UPSTREAM_NODE_ID=1 \ -v cluster-archives:/var/cluster_archive \ -p 5441:5432 \ --net mynet \ --net-alias pgslave1 \ --name pgslavetest \ paunin/postgresql-cluster-pgsql

   Pgpool
   docker run \ -e PCP_USER='pcp_user' \ -e PCP_PASSWORD='pcp_pass' \ -e PGPOOL_START_DELAY=120 \ -e REPLICATION_USER='replication_user' \ -e REPLICATION_PASSWORD='replication_pass' \ -e SEARCH_PRIMARY_NODE_TIMEOUT=5 \ -e DB_USERS='monkey_user:monkey_pass' \ -e BACKENDS='0:pgmaster:5432:1:/var/lib/postgresql/data:ALLOW_TO_FAILOVER,1:pgslave1::::' \ -p 5430:5432 \ -p 9898:9898 \ --net mynet \ --net-alias pgpool \ --name pgpooltest \ paunin/postgresql-cluster-pgpool

on the line BACKENDS='0:pgmaster:5432:1:/var/lib/postgresql/data:ALLOW_TO_FAILOVER,1:pgslave1::::' \ you can add more slaves to pgppool

2. Stop master pgmaster, slave pgslave1 would be promoted after a few secs,
3. Add new slave container docker run \ -e INITIAL_NODE_TYPE='standby' \ -e NODE_ID=3 \ -e NODE_NAME='node1' \ -e REPLICATION_PRIMARY_HOST='pgslave1' \ -e CLUSTER_NODE_NETWORK_NAME='pgmaster' \ -e REPLICATION_UPSTREAM_NODE_ID=2 \ -v cluster-archives:/var/cluster_archive \ -p 5432:5432 \ --net mynet \ --net-alias pgmaster \ --name pgmastertest3 \ paunin/postgresql-cluster-pgsql

on the following lines -e REPLICATION_PRIMARY_HOST='pgslave1' \ make sure you are pointing to the alias of the new master (pgslave1). -e REPLICATION_UPSTREAM_NODE_ID=2 \ make sure you are pointing to the new master node id (2). -e NODE_ID=3 \ make sure this id doesn't exists on the table repl_nodes. --net-alias pgmaster \ u can use the one from your old master, or use one that you already added on pgpool BACKENDS='0:pgmaster:5432:1:/var/lib/postgresql/data:ALLOW_TO_FAILOVER,1:pgslave1::::' \ otherwise if the new master fails repmgr wont be able to recover it.

Its a little manual, but it does what i need, and thats to add a new slave to the new master.