[root@localhost boot]# ll /boot/vmlinuz-*64
-rwxr-xr-x. 1 root root 14407720  7月  3 02:21 /boot/vmlinuz-5.14.0-474.el9.x86_64

systemctl [OPTIONS...] COMMAND [UNIT...]

# サービスの起動
[testuser@localhost ~]$ sudo systemctl start firewalld.service

# サービスの情報確認。現在はactive
[testuser@localhost ~]$ sudo systemctl status firewalld.service
● firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; preset: enabled)
     Active: active (running) since Thu 2024-08-08 21:56:06 JST; 8s ago
       Docs: man:firewalld(1)
   Main PID: 8066 (firewalld)
      Tasks: 2 (limit: 10948)
     Memory: 25.9M
        CPU: 309ms
     CGroup: /system.slice/firewalld.service
             mq8066 /usr/bin/python3 -s /usr/sbin/firewalld --nofork --nopid

 8月 08 21:56:06 localhost.localdomain systemd[1]: Starting firewalld - dynamic firewall daemon...
 8月 08 21:56:06 localhost.localdomain systemd[1]: Started firewalld - dynamic firewall daemon.

# サービスの停止
[testuser@localhost ~]$ sudo systemctl stop firewalld.service

# サービスの情報確認。現在はactive
[testuser@localhost ~]$ sudo systemctl status firewalld.service
○ firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; preset: enabled)
     Active: inactive (dead) since Thu 2024-08-08 21:56:56 JST; 1s ago
   Duration: 49.421s
       Docs: man:firewalld(1)
    Process: 8066 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUCCESS)
   Main PID: 8066 (code=exited, status=0/SUCCESS)
        CPU: 336ms

# システム起動時にfirewalld.serviceが起動しないように変更
[testuser@localhost ~]$ sudo systemctl disable firewalld.service
Removed "/etc/systemd/system/multi-user.target.wants/firewalld.service".
Removed "/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service".

# 状態がdisabledになったことを確認
[testuser@localhost ~]$ sudo systemctl status firewalld.service
○ firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; preset: enabled)
     Active: inactive (dead)
       Docs: man:firewalld(1)

# システム再起動起動
[testuser@localhost ~]$ sudo systemctl reboot
[sudo] testuser のパスワード:

# システム再起動後、firewalld.serviceが起動していないことを確認
[testuser@localhost ~]$ systemctl status  firewalld.service
○ firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; prese>
     Active: inactive (dead)
       Docs: man:firewalld(1)

journalctl [オプション]

[Journal]
SystemMaxUse=1G`

vim /etc/systemd/system/example.socket

[Unit]
Description=Example Socket

[Socket]
ListenStream=/run/example.sock

# 対応するサービスユニットを指定
Service=example.service

[Install]
WantedBy=sockets.target

vim /etc/systemd/system/example.service

[Unit]
Description=Example Service

[Service]
ExecStart=/usr/bin/python3 /root/server.py
WorkingDirectory=/root

[Install]
WantedBy=multi-user.target

vim /root/socket_access.py

#!/usr/bin/env python3

import socket
import time

# ソケットファイルのパス
SOCKET_FILE = '/run/example.sock'

# ソケットにアクセスする関数
def access_socket():
    try:
        client_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        client_socket.connect(SOCKET_FILE)
        print("Connected to socket")

    except socket.error as e:
        print(f"Connection failed: {e}, retrying in 1 second...")
        time.sleep(1)
    finally:
        client_socket.close()
        print("Socket closed")

if __name__ == '__main__':
    access_socket()

#!/usr/bin/env python3

import socket
import os

# ソケットファイルのパス
SOCKET_FILE = '/run/example.sock'

# 既存のソケットファイルを削除（存在する場合）
if os.path.exists(SOCKET_FILE):
    os.remove(SOCKET_FILE)


def main():

    print("Creating socket...")

    try:
        # ソケットの作成
        server = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        server.bind(SOCKET_FILE)
        server.listen()

        print(f"Server is listening on {SOCKET_FILE}")

    
        while True:
            server_connection, _ = server.accept()
            print("Connection established")
            
            try:
                while True:
                    data = server_connection.recv(1024)
                    if not data:
                        break
                    
                    request = data.decode()
                    print(f"Received request: {request}")
                    
                    # HTTPリクエストがGETであることを前提とする
                    if request.startswith("GET"):
                        # リクエストされたファイル名を取得する（簡易的な実装）
                        filename = request.split()[1].lstrip('/')
                        if filename == '':
                            filename = 'index.html'
                        
                        # ファイルが存在する場合はその内容を返す
                        if os.path.exists(filename):
                            with open(filename, 'rb') as file:
                                response_body = file.read()
                            response_headers = "HTTP/1.0 200 OK\r\n"
                            response_headers += f"Content-Length: {len(response_body)}\r\n"
                            response_headers += "Content-Type: text/html\r\n\r\n"
                            server_connection.sendall(response_headers.encode('ASCII') + response_body)
                        else:
                            response_body = b"<html><body><h1>404 Not Found</h1></body></html>"
                            response_headers = "HTTP/1.0 404 Not Found\r\n"
                            response_headers += f"Content-Length: {len(response_body)}\r\n"
                            response_headers += "Content-Type: text/html\r\n\r\n"
                            server_connection.sendall(response_headers.encode('ASCII') + response_body)
                    
                    # リクエスト処理の後、接続を閉じる
                    break

            finally:
                server_connection.close()
                print("Connection closed")

    finally:
        server.close()
        print("Socket closed.")

if __name__ == '__main__':
    main()

vim /root/client.py

#!/usr/bin/env python3

import socket
import time
import subprocess
from socket_access import access_socket  # ファイル名の相対パスでインポート

# ソケットファイルのパス
SOCKET_FILE = '/run/example.sock'

# ソケットに指定したバイト数を書き込む関数
def send_msg(sock, msg):
    total_sent_len = 0
    total_msg_len = len(msg)
    while total_sent_len < total_msg_len:
        sent_len = sock.send(msg[total_sent_len:])
        if sent_len == 0:
            raise RuntimeError('Socket connection broken')
        total_sent_len += sent_len

# ソケットから接続が終わるまでバイト列を読み込むジェネレータ関数
def recv_msg(sock, chunk_len=1024):
    while True:
        received_chunk = sock.recv(chunk_len)
        if len(received_chunk) == 0:
            break
        yield received_chunk

def is_service_active(service_name):
    result = subprocess.run(['systemctl', 'is-active', service_name], capture_output=True, text=True)
    return result.stdout.strip() == 'active'

def wait_for_service_activation(service_name):
    while not is_service_active(service_name):
        print(f"{service_name} is not active. Waiting for 1 second...")
        time.sleep(1)
    
    print(f"{service_name} is now active.")


def main():
    client_socket = None
    try:
        # ソケットにアクセスする関数を呼び出す
        access_socket()
        time.sleep(1)

        # example.serviceがアクティブになるまで待機する
        wait_for_service_activation('example.service')
        time.sleep(1)
                

        while True:
            try:
                client_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
                print("Socket created.")
                client_socket.connect(SOCKET_FILE)
                break  # 接続成功でループを抜ける
            except socket.error as e:
                print(f"Connection failed: {e}, retrying in 1 second...")
                time.sleep(1)

        request_text = 'GET / HTTP/1.0\r\n\r\n'
        request_bytes = request_text.encode('ASCII')
        send_msg(client_socket, request_bytes)
        print("Request sent to server.")

        received_bytes = b"".join(recv_msg(client_socket))
        received_text = received_bytes.decode('ASCII')
        print("Response received from server:")
        print(received_text)

    except Exception as e:
        print(f"An error occurred: {e}")

    finally:
        if client_socket:
            client_socket.close()
            print("Socket closed.")


if __name__ == '__main__':
    main()

<!doctype html>
<html>
    <head>
        <title>Hello World</title>
    </head>
    <body>
        <h1>Hello World</h1>
    </body>
</html>

systemctl start example.socket

systemctl status example.socket ; systemctl status example.service

[root@localhost ~]# systemctl status example.socket ; systemctl status example.service
● example.socket - Example Socket
     Loaded: loaded (/etc/systemd/system/example.socket; disabled; preset: disabled)
     Active: active (listening) since Tue 2024-07-16 18:46:27 JST; 6s ago
      Until: Tue 2024-07-16 18:46:27 JST; 6s ago
   Triggers: ● example.service
     Listen: /run/example.sock (Stream)
     CGroup: /system.slice/example.socket

 7月 16 18:46:27 localhost.localdomain systemd[1]: Listening on Example Socket.
○ example.service - Example Service
     Loaded: loaded (/etc/systemd/system/example.service; disabled; preset: disabled)
     Active: inactive (dead)
TriggeredBy: ● example.socket

 7月 16 18:44:38 localhost.localdomain systemd[1]: Stopped Example Service.
 7月 16 18:45:13 localhost.localdomain systemd[1]: Started Example Service.
 7月 16 18:46:16 localhost.localdomain systemd[1]: Stopping Example Service...
 7月 16 18:46:16 localhost.localdomain systemd[1]: example.service: Deactivated successfully.
 7月 16 18:46:16 localhost.localdomain systemd[1]: Stopped Example Service.

python3 ./client.py

[root@localhost ~]# python3 ./client.py 
Socket created.
Request sent to server.
Response received from server:
HTTP/1.0 200 OK
Content-Length: 141
Content-Type: text/html

<!doctype html>
<html>
    <head>
        <title>Hello World</title>
    </head>
    <body>
        <h1>Hello World</h1>
    </body>
</html>

Socket closed.

systemctl stop example.socket ;  systemctl stop example.service ; systemctl daemon-reload