script

#!/bin/bash
rep_user="replica"
witnessIp=192.168.0.106
#primaryIp=192.168.0.105
#standbyIp=192.168.0.107
# Read IP address
read -p "Enter primary ip: " primaryIp
read -p "Enter standby ip: " standbyIp
ssh root@$primaryIp << EOT
echo "Connect to primary server"
systemctl enable postgresql
echo "Change postgresql.conf"
sed -i "s/#listen_addresses = 'localhost'/listen_addresses = '*'/; s/#wal_level = replica/wal_level = replica/; s/#synchronous_commit = on/synchronous_commit = on/; s/#max_wal_senders = 10/max_wal_senders = 10/; s/#wal_keep_segments = 0/wal_keep_segments = 10/; s/#synchronous_standby_names = ''/synchronous_standby_names = '*'/" /etc/postgresql/12/main/postgresql.conf
echo "Add rull to pg_sql.conf"
if grep -Fxq 'host replication $rep_user $standbyIp/32 trust' /etc/postgresql/12/main/pg_hba.conf
then echo 'Rule exist'
else echo 'host replication $rep_user $standbyIp/32 trust' >> /etc/postgresql/12/main/pg_hba.conf
fi
if grep -Fxq 'host all all 0.0.0.0/0 md5' /etc/postgresql/12/main/pg_hba.conf
then echo 'Rule exist'
else echo 'host all all 0.0.0.0/0 md5' >> /etc/postgresql/12/main/pg_hba.conf
fi
echo "Create $rep_user"
sudo -S -u postgres psql -c "CREATE USER $rep_user REPLICATION PASSWORD 'A';"
systemctl restart postgresql
EOT
echo "Primary server finished"

ssh root@$standbyIp << EOT
echo "Connect to standby server"
apt update
apt upgrade -y
apt install -y postgresql
systemctl enable postgresql
echo "Posstgresql installed"
systemctl stop postgresql
rm -rf /var/lib/postgresql/12/main/
sudo -S -u postgres pg_basebackup -R -h $primaryIp -U $rep_user -D /var/lib/postgresql/12/main -P -w
echo "Backup is succsessful"
sed -i "s/#listen_addresses = 'localhost'/listen_addresses = '*'/; s/#hot_standby = on/hot_standby = on/" /etc/postgresql/12/main/postgresql.conf
echo "Changed postgresql.conf"
if grep -Fxq 'host all all 0.0.0.0/0 md5' /etc/postgresql/12/main/pg_hba.conf
then echo 'Rule exist'
else echo 'host all all 0.0.0.0/0 md5' >> /etc/postgresql/12/main/pg_hba.conf
fi
systemctl start postgresql
echo "Create agent"
cat > /etc/init.d/script << AUF
#!/bin/bash
while true
do
	if pg_isready -h $primaryIp -q
	then
		echo "Primary is available"
	else
		if ping -c 1 -q $witnessIp
		then
			wall "Primary is not available. Promote StandbyIp"
			sudo -S -u postgres psql -c "SELECT pg_promote(false);"
			break;
		else
			wall "Primary and witness is not available"
		fi
	fi
	sleep 1
done
wall "final"
AUF
cat > /etc/systemd/system//script.service << AUF
[Unit]
Description=My service
After=network.target
[Service]
Type=oneshot
User=root
ExecStart=/etc/init.d/script
[Install]
WantedBy=multi-user.target
AUF
chmod +x /etc/init.d/script 
systemctl enable script.service
systemctl restart script.service
EOT
echo "StandBy server finished"