How to bootstrap a Patroni cluster using vagrant

This Vagrantfile is bootstrapping a fresh cluster based on CentOS7 with:

• servers e1, e2 and e3 hosting a etcd cluster
• servers p1 and p2 hosting a Patroni/PostgreSQL cluster
• watchdog enabled

Note that NTP is enabled by default (using chrony) in the vagrant box used (centos/7). No need to set it up ourselves.

Prerequisites:

You need vagrant and vagrant-libvirt. Everything is tested with versions 2.0.2 and 0.0.40. Please, report your versions if it works with inferior ones.

apt install make vagrant vagrant-libvirt libvirt-clients # for Debian-like
yum install make vagrant vagrant-libvirt libvirt-client # for RH-like
dnf install make vagrant vagrant-libvirt libvirt-client # for recent RH-like
systemctl enable --now libvirtd

Creating the cluster

To create the cluster, run:

cd vagrant-patroni
make all

After some minutes and tons of log messages, you can connect to your servers using eg.:

vagrant ssh p1

Setup patronictl:

/usr/local/bin/patronictl configure \
  --config-file "${HOME:?}/.config/patroni/patronictl.yaml" \
  --dcs "etcd://10.20.30.55:2379" \
  --namespace "/service"

Play with the cluster!

/usr/local/bin/patronictl list patroni-demo
/usr/local/bin/patronictl switchover --help
/usr/local/bin/patronictl switchover patroni-demo --master p2 --candidate p1 --force

NOTE: We are using patroni's ability to use etcd api v3. Depending on your etcd version, you might need to use the following to see patroni's keys with etcdctl.

export ETCDCTL_API=3

Destroying the cluster

To destroy your cluster, run:

vagrant destroy -f

Adding vip-manager to the mix

vip-manager is designed to manage a VIP for your PostgreSQL cluster, it will automatically start it on the node where PostgreSQL is the leader.

Follow the "Creating the cluster" procedure but use the following command instead of make all:

make vipmanager

With the default configuration, the VIP will be 10.20.30.50.

Tips

Find all existing VM created by vagrant on your system:

vagrant global-status