Actively Sending Monitoring Data to Zabbix Server Using zabbix_sender

>>> zabbix_sender -z 10.0.0.1 -p 10051 -s "rs_solrmaster" -k "get_number_of_solr_index_update" -o 4
Note that get_number_of_solr_index_update is a key that must be created in advance on the host rs_solrmaster, and it must be of type zabbix trapper.
#usage: zabbix_sender [-Vhv] {[-zpsI] -ko | [-zpI] -T -i  -r} [-c ]
#Options:
#  -c --config                    Absolute path to the configuration file
#  -z --zabbix-server             IP address of the Zabbix server or Zabbix proxy
#  -p --port                      Port of the Zabbix server or Zabbix proxy, default is 10051
#  -s --host                      Host name, referring to the host name configured in Zabbix
#  -I --source-address            Source IP address
#  -k --key                       Name of the Zabbix trapper key
#  -o --value                     Value of the item to be sent
#  -i --input-file <input type="text" />   Batch send data via a file, with one record per line in the format hostname,key,value separated by spaces. If the hostname contains spaces, use double quotes.
>>> cat trapper_key.txt
"zabbix server" key1 10
"zabbix proxy" key2 20
10.0.0.2 key3 30
>>> zabbix_sender -z 10.0.0.1 -i trapper_key.txt

Thus, we can send monitoring data to Zabbix anytime and anywhere. Since Zabbix only provides the `zabbix_sender` binary for sending data, calling a binary executable directly within a program is considered poor practice. Is there a more elegant solution? (Note that the Zabbix API documentation does not cover trapper keys). Yes, pay attention to what comes next.
The communication between `zabbix_sender` and `zabbix_server` uses the TCP protocol. This means `zabbix_sender` sends a TCP packet with a fixed-format DATA segment to `zabbix_server`, which then parses and processes the request. Therefore, if we can determine the data format of this DATA segment, we can simulate `zabbix_sender` using a program.
Let’s look at two articles first:
Research on Zabbix Sender Protocol | itnihao
Zabbix Sender 2.0 Protocol Documentation
From these, we can derive the complete format of a `zabbix_sender` request packet as follows:

As seen, the basic Zabbix sender data protocol consists of ‘Z”B”X”D’ + 1-byte protocol version number + 8-byte data length + JSON data. According to the documentation, the JSON data format for the request is:

{
        "request":"sender data",
        "data":[
                {
                        "host":"Host name 1",
                        "key":"item_key",
                        "value":"33"},
                {
                        "host":"Host name 2",
                        "key":"item_key",
                        "value":"55"
                }
        ]
}

This gives us the basic program logic, which is:
♠ Construct a data packet conforming to the Zabbix sender protocol, with the format ‘4sBqns’ (where n is the length of the JSON string)
♠ Send the data packet to the Zabbix server port
♠ Process the response
Below is an example implementation in Python:

#!/usr/bin/env python

import struct
import json
import socket


class ZabbixSender:
        def __init__(self,zbx_server_host,zbx_server_port):
                self.zbx_server_host=zbx_server_host
                self.zbx_server_port=zbx_server_port
                self.zbx_header='ZBXD'
                self.zbx_protocols_version=1
                self.zbx_send_value={'request':'sender data','data':[]}
        def add_data(self,host,key,value):
                add_data={'host':host,'key':key,'value':value}
                self.zbx_send_value['data'].append(add_data)
        # Encapsulate data packet according to protocol
        def make_send_data(self):
                zbx_send_json=json.dumps(self.zbx_send_value)
                zbx_send_json_len=len(zbx_send_json)
                self.zbx_send_data=struct.pack("<4sBq"+str(zbx_send_json_len)+"s",'ZBXD',1,zbx_send_json_len,zbx_send_json)
        def send(self):
                self.make_send_data()
                zbx_server_socket=socket.socket()
                zbx_server_socket.connect((self.zbx_server_host,self.zbx_server_port))
                zbx_server_write_df=zbx_server_socket.makefile('wb')
                zbx_server_write_df.write(self.zbx_send_data)
                zbx_server_write_df.close()
                zbx_server_read_df=zbx_server_socket.makefile('rb')
                zbx_response_package=zbx_server_read_df.read()
                zbx_server_read_df.close()
                # Decode data packet according to protocol
                zbx_response_data=struct.unpack("<4sBq"+str(len(zbx_response_package) - struct.calcsize("<4sBq"))+"s",zbx_response_package)
                return zbx_response_data[3]

if __name__ == '__main__':
        zabbix_sender=ZabbixSender('10.0.0.1',10051)
        zabbix_sender.add_data('solrmaster','get_number_of_solr_index_update',60)
        response=zabbix_sender.send()
        print response