如何透過Crontab執行Python腳本監控伺服器狀態並建立新實例？

透過Crontab 執行Python 腳本

問題：使用者在嘗試使用Linux crontab 執行Python 腳本時可能會遇到困難，特別是當旨在每10 分鐘運行一次。各種解決方案（例如修改 anacron 檔案或使用 crontab -e）可能無效，讓使用者質疑是否需要重新啟動特定服務或應編輯設定檔。

答案：

要解決此問題，請參閱以下指南：

1. 編輯crontab> 在 在
在>終端機中輸入crontab -e 以存取crontab .
2. 新增腳本：
將所需的命令追加到crontab 檔案中，如下所示，每10 分鐘執行一次腳本：

*/10 * * * * /usr/bin/python /home/souza/Documents/Listener/listener.py

3. 儲存crontab 檔案：
按Ctrl X 退出，然後按Y 儲存變更。

文件配置：

需要編輯的文件是 crontab 文件，可以使用 crontab -e 命令存取和修改該文件。

腳本：

您的 Python 腳本必須正確配置執行所需的操作。作為參考，這裡是提供的腳本，適合每 10 分鐘執行一次：

<code class="python">#!/usr/bin/python
# -*- coding: iso-8859-15 -*-

import json
import os
import pycurl
import sys
import cStringIO

if __name__ == "__main__":

    name_server_standart = "Server created by script %d"
    json_file_standart = """{ "server" : {  "name" : "%s", "imageRef" : "%s", "flavorRef" : "%s" } }"""

    curl_auth_token = pycurl.Curl()

    gettoken = cStringIO.StringIO()

    curl_auth_token.setopt(pycurl.URL, "http://192.168.100.241:8774/v1.1")
    curl_auth_token.setopt(pycurl.POST, 1)
    curl_auth_token.setopt(
        pycurl.HTTPHEADER,
        ["X-Auth-User: cpca", "X-Auth-Key: 438ac2d9-689f-4c50-9d00-c2883cfd38d0"],
    )

    curl_auth_token.setopt(pycurl.HEADERFUNCTION, gettoken.write)
    curl_auth_token.perform()
    chg = gettoken.getvalue()

    auth_token = chg[
        chg.find("X-Auth-Token: ") + len("X-Auth-Token: ") : chg.find("X-Server-Management-Url:") - 1
    ]

    token = "X-Auth-Token: {0}".format(auth_token)
    curl_auth_token.close()

    # ----------------------------

    getter = cStringIO.StringIO()
    curl_hab_image = pycurl.Curl()
    curl_hab_image.setopt(pycurl.URL, "http://192.168.100.241:8774/v1.1/nuvemcpca/images/7")
    curl_hab_image.setopt(pycurl.HTTPGET, 1)  # Removing this line allows the script to run.
    curl_hab_image.setopt(pycurl.HTTPHEADER, [token])

    curl_hab_image.setopt(pycurl.WRITEFUNCTION, getter.write)
    # curl_list.setopt(pycurl.VERBOSE, 1)
    curl_hab_image.perform()
    curl_hab_image.close()

    getter = cStringIO.StringIO()

    curl_list = pycurl.Curl()
    curl_list.setopt(pycurl.URL, "http://192.168.100.241:8774/v1.1/nuvemcpca/servers/detail")
    curl_list.setopt(pycurl.HTTPGET, 1)  # Removing this line allows the script to run.
    curl_list.setopt(pycurl.HTTPHEADER, [token])

    curl_list.setopt(pycurl.WRITEFUNCTION, getter.write)
    # curl_list.setopt(pycurl.VERBOSE, 1)
    curl_list.perform()
    curl_list.close()

    # ----------------------------

    resp = getter.getvalue()

    con = int(resp.count("status"))

    s = json.loads(resp)

    lst = []

    for i in range(con):
        lst.append(s["servers"][i]["status"])

    for j in range(len(lst)):
        actual = lst.pop()
        print actual

        if actual != "ACTIVE" and actual != "BUILD" and actual != "REBOOT" and actual != "RESIZE":

            print "Enters the if block."

            f = file("counter", "r+w")

            num = 0
            for line in f:
                num = line

            content = int(num) + 1

            ins = str(content)

            f.seek(0)
            f.write(ins)
            f.truncate()
            f.close()

            print "Increments the counter."

            json_file = file("json_file_create_server.json", "r+w")

            name_server_final = name_server_standart % content
            path_to_image = "http://192.168.100.241:8774/v1.1/nuvemcpca/images/7"
            path_to_flavor = "http://192.168.100.241:8774/v1.1/nuvemcpca/flavors/1"

            new_json_file_content = json_file_standart % (
                name_server_final,
                path_to_image,
                path_to_flavor,
            )

            json_file.seek(0)
            json_file.write(new_json_file_content)
            json_file.truncate()
            json_file.close()

            print "Updates the JSON file."

            fil = file("json_file_create_server.json")
            siz = os.path.getsize("json_file_create_server.json")

            cont_size = "Content-Length: %d" % siz
            cont_type = "Content-Type: application/json"
            accept = "Accept: application/json"

            c_create_servers = pycurl.Curl()

            logger = cStringIO.StringIO()

            c_create_servers.setopt(pycurl.URL, "http://192.168.100.241:8774/v1.1/nuvemcpca/servers")

            c_create_servers.setopt(pycurl.HTTPHEADER, [token, cont_type, accept, cont_size])

            c_create_servers.setopt(pycurl.POST, 1)

            c_create_servers.setopt(pycurl.INFILE, fil)

            c_create_servers.setopt(pycurl.INFILESIZE, siz)

            c_create_servers.setopt(pycurl.WRITEFUNCTION, logger.write)

            print "Executes the curl command."

            c_create_servers.perform()

            print logger.getvalue()

            c_create_servers.close()</code>

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