Windows Agent ls to start only the first time after installation

[StormScorpion]

Hi,
I created an Ansible role to install and configure the Zabbix Agent on Windows servers.
This works well beside the fact that the first start after the installation fails. Afterwards, I can start the Zabbix Agent service or reboot the system. It works everytime.

Based on the logs it fails to start a listener on port 10050 - but its supposed to run in ActiveMode.
The config file was written at 8:14:14, the service started at 8:14:28 - 14 seconds later. So the write config step was already done at the time the service was started.

Log:

First start after installation with default config

6140:20240731:081351.378 Starting Zabbix Agent [HOSTNAME]. Zabbix 6.4.17 (revision c12261f00b4).
6140:20240731:081351.379 **** Enabled features ****
6140:20240731:081351.381 IPv6 support: YES
6140:20240731:081351.382 TLS support: YES
6140:20240731:081351.383 **************************
6140:20240731:081351.384 using configuration file: C:\Program Files\Zabbix Agent\zabbix_agentd.conf
6140:20240731:081353.200 agent #0 started [main process]
10396:20240731:081353.202 agent #1 started [collector]
9308:20240731:081353.204 agent #2 started[listener #1]
10744:20240731:081353.206 agent #3 started[listener #2]
7592:20240731:081353.207 agent #4 started[listener #3]
7512:20240731:081427.669 Zabbix Agent received stop request.
7512:20240731:081428.661 Zabbix Agent stopped. Zabbix 6.4.17 (revision c12261f00b4).

First after deployed configuration - failed
8508:20240731:081428.712 Starting Zabbix Agent [hostname]. Zabbix 6.4.17 (revision c12261f00b4).
8508:20240731:081428.713 **** Enabled features ****
8508:20240731:081428.716 IPv6 support: YES
8508:20240731:081428.719 TLS support: YES
8508:20240731:081428.720 **************************
8508:20240731:081428.723 using configuration file: C:\Program Files\Zabbix Agent\zabbix_agentd.conf
8508:20240731:081428.729 listener failed: bind() for [[-]:10050] failed: [0x00002740] Only one usage of each socket address (protocol/network address/port) is normally permitted.
8508:20240731:081428.730 Zabbix Agent stopped. Zabbix 6.4.17 (revision c12261f00b4).

Second start - working
9292:20240731:082810.338 Starting Zabbix Agent [HOSTNAME]. Zabbix 6.4.17 (revision c12261f00b4).
9292:20240731:082810.340 **** Enabled features ****
9292:20240731:082810.341 IPv6 support: YES
9292:20240731:082810.342 TLS support: YES
9292:20240731:082810.342 **************************
9292:20240731:082810.343 using configuration file: C:\Program Files\Zabbix Agent\zabbix_agentd.conf
9292:20240731:082811.023 agent #0 started [main process]
2756:20240731:082811.024 agent #1 started [collector]
5480:20240731:082811.025 agent #2 started[listener #1]
7616:20240731:082811.026 agent #3 started[listener #2]
9312:20240731:082811.028 agent #4 started[listener #3]
1540:20240731:082811.029 agent #5 started [active checks #1]

Config

# This is a configuration file for Zabbix agent service (Windows)
# To get more information about Zabbix, visit http://www.zabbix.com

############ GENERAL PARAMETERS #################
# Logging
LogFile=C:\Program Files\Zabbix Agent\zabbix_agentd.log
LogFileSize=1024

ServerActive=zabbixserver.mycorp.local
Hostname=hostname
RefreshActiveChecks=60
Server=127.0.0.1

############ ADVANCED PARAMETERS #################
Include=C:\Program Files\Zabbix Agent\zabbix_agentd.d\

# PSK Settings:
TLSConnect=psk
TLSAccept=psk
TLSPSKFile=C:\Program Files\Zabbix Agent\psk.key
TLSPSKIdentity=hostname

[Markku]

Note the really fast start attempt just after the previous instance was stopped:

7512:20240731:081427.669 Zabbix Agent received stop request.
7512:20240731:081428.661 Zabbix Agent stopped. Zabbix 6.4.17 (revision c12261f00b4).
...
8508:20240731:081428.712 Starting Zabbix Agent [hostname]. Zabbix 6.4.17 (revision c12261f00b4).
...
8508:20240731:081428.729 listener failed: bind() for [[-]:10050] failed: [0x00002740] Only one usage of each socket address (protocol/network address/port) is normally permitted.

so maybe the socket listener was not really yet removed during those 50-70 ms?

Why does it first start the agent and then stop + start immediately again?

Markku

[Markku]

Note the really fast start attempt just after the previous instance was stopped:

7512:20240731:081427.669 Zabbix Agent received stop request.
7512:20240731:081428.661 Zabbix Agent stopped. Zabbix 6.4.17 (revision c12261f00b4).
...
8508:20240731:081428.712 Starting Zabbix Agent [hostname]. Zabbix 6.4.17 (revision c12261f00b4).
...
8508:20240731:081428.729 listener failed: bind() for [[-]:10050] failed: [0x00002740] Only one usage of each socket address (protocol/network address/port) is normally permitted.

so maybe the socket listener was not really yet removed during those 50-70 ms?

Why does it first start the agent and then stop + start immediately again?

Markku

[Markku]

Btw, if you are not using passive items, you can disable the listener:

https://www.zabbix.com/documentation/6.4/en/manual/appendix/config/zabbix_agentd_win#startagents

Set StartAgents to 0.

(If later using Agent 2, then "Server=" makes the same thing, IIRC.)

Markku

[StormScorpion]

Workaround: configured Windows service to restart 5s after failure, now the service stays running after installation

[StormScorpion]

Why does it first start the agent and then stop + start immediately again?

I install the Agent using chocolatey, it starts the service with default config right after installation. Then I write the config and restart the service.

But thanks, that was the right hint. I added an explicit stop after install, that solved the issue.