Postpone OH startup until your external DB is online

[stfn82 (Stefan)]

In my setup I use a MariaDB server, running in another VM. When I restart my VM server OH sometimes loads faster then my DB and I get persistence errors. Only solution is to restart OH after my DB has fully started.

This simple solution let’s OH wait until my DB is available.

Create a file, for example ismysqlonline.sh:

#!/bin/bash
while ! echo 2>/dev/null > /dev/tcp/YOUR_DB_IP/YOUR_DB_PORT; do
  echo "waiting for MySQL/MariaDB to come online..."
  sleep 5s
done
  echo "MySQL/MariaDB is running."
exit 0

Edit /lib/systemd/system/openhab.service and add the following line before ExecStart:

ExecStartPre=/home/openhab3/ismysqlonline.sh (Modify to suit your location and filename)

Reload systemd: sudo systemctl daemon-reload

Resulting in:

Mar 12 17:26:40 openhab3 systemd[1]: Starting openHAB - empowering the smart home...
Mar 12 17:26:40 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:26:45 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:26:50 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:26:55 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:27:00 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:27:05 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:27:10 openhab3 ismysqlonline.sh[8666]: waiting for MySQL/MariaDB to come online...
Mar 12 17:27:15 openhab3 ismysqlonline.sh[8666]: MySQL/MariaDB is running.
Mar 12 17:27:15 openhab3 systemd[1]: Started openHAB - empowering the smart home.

[chrismast (chris)]

Thanks!

Maybe just to add, depending on your hypervisor you can also define a start up order.
I run PSQL as my db on Proxmox and it always starts earlier than OH due to the start up order index.

[stfn82 (Stefan)]

I’m using LXC with these parameters:

boot.autostart: “true”
boot.autostart.delay: “10”
boot.autostart.priority: “10”

Of course different values for each container. Most of the time it works, sometimes not. That’s now fixed with above script.