patroni-class

Master class repo for learning patroni, consul, walg, s3

How to:

Let's check if we have docker up and running

docker version

Let's init first 3 containers h0, h1, h2

ansible-playbook -i inventory init.yml

Let's check if they were deployed ok

docker ps

Let's check how dynamic_inventory is working

./dynamic_inventory.py

Now use dynamic_inventory.py as inventory for consul deploy

ansible-playbook -i dynamic_inventory.py consul.yml

Checking consul cluster is ok

docker logs h0

Let's perform simple init in postgres cluster

./dynamic_inventory.py

• (use less)
• h0 is 172.18.0.2

Add one node into cluster with simple init

ansible-playbook -i dynamic_inventory.py patroni.yml --tags=patroni-init --limit=172.18.0.2

Check if it is up and running

docker exec -it h0 docker ps
docker exec -it h0 docker logs pg-h0

Let's check dns records for master

docker exec -it h0 docker exec -it pg-h0 ping master.patroni-class.service.consul

and deploy slave

ansible-playbook -i dynamic_inventory.py patroni.yml --tags=patroni-init --limit=172.18.0.3

check if it registred

docker exec -it h0 docker exec -it pg-h0 ping replica.patroni-class.service.consul

and check logs of first slave

docker exec -it h1 docker logs --tail 100 pg-h1

Let's check if it data replication is working

Create table on master

docker exec -it h0 docker exec -it pg-h0 gosu postgres psql -c "CREATE TABLE bins  AS SELECT * FROM GENERATE_SERIES(1, 10000) AS id;"

Read data from slave

docker exec -it h1 docker exec -it pg-h1 gosu postgres psql -c "SELECT max(id) from bins;"

Let's perform switchover

docker exec -it h1 docker exec -it pg-h1 bash
patronictl --help

Check existing state

patronictl -c /var/lib/postgresql/patroni.yml list

Let's do the trick

patronictl -c /var/lib/postgresql/patroni.yml switchover

Check existing state

patronictl -c /var/lib/postgresql/patroni.yml list
ping master.patroni-class.service.consul
exit

Let's disconnect current master

docker network disconnect bridge h1

Failover works

docker exec -it h0 docker exec -it pg-h0 patronictl -c /var/lib/postgresql/patroni.yml list

Turn on again and see fencing

docker network connect bridge h1
docker exec -it h0 docker exec -it pg-h0 patronictl -c /var/lib/postgresql/patroni.yml list

Let's init cluster from s3

we changed scope from patroni-class to patroni-class-walg

ansible-playbook -i dynamic_inventory.py patroni.yml --tags=patroni-init-walg --limit=172.18.0.4

and check logs

docker exec -it h2 docker logs --tail 100 pg-h2

Read data from walg master

docker exec -it h2 docker exec -it pg-h2 gosu postgres psql -c "SELECT max(id) from walg;"

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