MySQL: Service is down || Zabbix Agent ubuntu - mysql

Question

I have configured Mysql for Zabbix Server as mentioned in the link below.
https://sbcode.net/zabbix/setup_mysql_database_monitoring/
It's Works fine. I was able to monitor Mysql parameters.
I then configured and added Zabbix Agent successfully.
But when I do the same Mysql Configuration on the Zabbix Agent server Mysql service was showing down.
https://sbcode.net/zabbix/setup_mysql_database_monitoring/
On Zabbix Agent Ubuntu server, I checked Mysql service is showing an Active state and In mysql DB I have create a new user called zbx_monitor and grant it the required permissions for the database server too.
I search some configurations from internet but it did't resolve the issue.
If anyone know how to configured Mysql for Zabbix Agent Server Ubuntu will be appriciated.
Thanks!

Answer 1

I had same problem and i resolved it by adding "HOME=/var/lib/zabbix" in each line at the template file (/etc/zabbix/zabbix_agentd.d/template_db_mysql.conf)
For example "UserParameter=mysql.ping[*], HOME=/var/lib/zabbix mysqladmin -h"$1" -P"$2" ping"
Agent service restart is required. have fun!

Answer 2

Problem: Docker Automatically Inserting iptables Rules
I monitor on local RFC 1918 addresses, so there is absolutely no need to NAT or Masquerade any of the traffic.
But that is exactly what Docker does.
Docker, "helpfully" inserts rules into iptables which masquerades & NAT's traffic, busting connectivity between the Agent and Zabbix Server.
Solution:
On the HOST RUNNING THE AGENT, identify and delete the offending rules as below
IPtables ** NAT ** Table:
Identify the rules in the ** NAT ** table which are masquerading & NAT'ing traffic. You can determine which rules have effect because their packet counters will be incremented:
sudo iptables -t nat -nvx -L --line-numbers
Delete each bad rule in ** NAT ** table by RULE NUMBER:
sudo iptables -t nat -D POSTROUTING <Rule Number>
sudo iptables -t nat -D DOCKER <Rule Number>
Obviously don't use the angle brackets in your command, only specify the rule number
IPtables ** FORWARD ** Chain:
Identify the bad rules in the ** FORWARD ** chain. Note that we just remove the - nat switch in the command this time:
sudo iptables -nvx -L --line-numbers
Below are some specimen FORWARD rules:
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
num pkts bytes target prot opt in out source destination
1 145702 279577023 DOCKER-ISOLATION-STAGE-2 all -- br-33d625bd029c !br-33d625bd029c 0.0.0.0/0 0.0.0.0/0
2 40104066 107106936701 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Chain DOCKER-ISOLATION-STAGE-2 (1 references)
num pkts bytes target prot opt in out source destination
1 0 0 DROP all -- * br-33d625bd029c 0.0.0.0/0 0.0.0.0/0
2 29910 1794560 DROP all -- * docker0 0.0.0.0/0 0.0.0.0/0
3 116324 283419930 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Look at rule #1 in chain "Chain DOCKER-ISOLATION-STAGE-1": the target is "Chain DOCKER-ISOLATION-STAGE-2". We can see it has effect and is dropping traffic because the packet counter is incrementing.
Now look at chain "Chain DOCKER-ISOLATION-STAGE-2" which drops the traffic in rule #2. Again, we can see the rule has effect and is actually DROPPING traffic.
Delete each bad rule in the ** FORWARD ** chain by RULE NUMBER:
sudo iptables -D DOCKER-ISOLATION-STAGE-1 <Rule Number>
sudo iptables -D DOCKER-ISOLATION-STAGE-2 <Rule Number>
Using the specimen iptables data above, we'd execute:
sudo iptables -D DOCKER-ISOLATION-STAGE-1 1
sudo iptables -D DOCKER-ISOLATION-STAGE-2 2
If you check your Zabbix monitoring, you should see the warning has cleared.
Rebuilding Containers
Please note that when you rebuild your Docker containers, the bad rules will be restored and you'll have to delete them again.
However, merely restarting a container does NOT restore the duff iptables rules.