使用Python指令碼自動運行Catalyst 9000交換機
簡介
本文說明如何使用Python指令碼擴展EEM，以在Catalyst 9000交換機上自動執行配置和資料收集。
必要條件
需求
思科建議您瞭解並熟悉以下主題：
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Cisco IOS®和Cisco IOS® XE EEM
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應用託管和訪客外殼
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Python指令碼
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Linux命令
採用元件
本文中的資訊係根據以下軟體和硬體版本：
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Catalyst 9200
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Catalyst 9300
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Catalyst 9400
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Catalyst 9500
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Catalyst 9600
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Cisco IOS XE 17.9.1及更高版本
附註：請參閱適當的組態設定指南來瞭解使用的命令，以便在其他思科平台上啟用這些功能。
附註：Catalyst 9200L交換器不支援訪客Shell。
附註：Cisco TAC不支援這些指令碼，這些指令碼按原樣提供，用於教學目的。
本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除（預設）的組態來啟動。如果您的網路運作中，請確保您瞭解任何指令可能造成的影響。
慣例
如需檔案慣例的相關資訊，請參閱思科技術提示慣例。
背景資訊
Guest Shell和Python指令碼
在Cisco Catalyst 9000系列交換機上託管應用可為合作夥伴和開發人員帶來創新機會，因為網路裝置可以與應用運行時環境合併。
它支援容器化應用，提供與主作業系統和Cisco IOS XE核心的完全隔離。這種分離可確保託管應用的資源分配與核心路由和交換功能不同。
適用於Cisco IOS XE裝置的應用託管基礎設施稱為IOx(Cisco IOS + Linux)，它有助於將思科、合作夥伴和第三方開發人員開發的應用和服務託管到網路裝置上，確保跨各種硬體平台無縫整合。
Guest Shell是一種專用容器部署，它舉例說明了有利於系統部署的應用程式。
Guest Shell提供基於Linux的虛擬化環境，旨在運行自定義Linux應用程式（包括Python），以實現對思科裝置的自動控制和管理。Guest Shell容器允許使用者在系統中運行指令碼和應用。具體來說，在Intel x86平台上，Guest Shell容器是一個Linux容器(LXC)，其中包含CentOS 8.0最小根檔案系統。在Cisco IOS XE Amsterdam 17.3.1及更高版本中，僅支援Python V3.6。在運行時可使用CentOS 8.0中的Yum實用程式安裝其他Python庫。也可以使用Pip安裝包(PIP)安裝或更新Python包。
Guest Shell包括Python應用程式程式設計介面(API)，允許使用Python CLI模組運行Cisco IOS XE命令。通過這種方式，Python指令碼增強了自動化功能，為網路工程師提供了一種多功能工具，用於開發用於自動執行配置和資料收集任務的指令碼。雖然這些指令碼可以通過CLI手動運行，但是也可以與EEM指令碼一起用於響應特定事件，如系統日誌消息、介面事件或命令運行。實際上，任何可能觸發EEM指令碼的事件也可用於觸發Python指令碼，從而擴大Cisco Catalyst 9000交換機內部的自動化潛力。
安裝Guest Shell後，將在快閃記憶體檔案系統中自動建立來賓共用目錄。這是可以通過Python指令碼和訪客Shell訪問的檔案系統。為確保使用堆疊時正確同步，請將此資料夾保持在50 MB以下。
將Python與EEM指令碼配合使用的優點
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Python允許在Python指令碼中處理複雜的邏輯（如正規表示式、循環和匹配），從而擴展了EEM指令碼的自動化功能。此功能提供了建立更強大的EEM指令碼的機會。
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作為一種著名的程式語言，Python降低了希望自動化Cisco IOS XE裝置的網路工程師的進入障礙。此外，它還提供了可維護性和可讀性。
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Python還提供錯誤處理功能以及強大的標準庫。
對EEM指令碼使用Python的注意事項
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Guest Shell在預設情況下未啟用，因此需要先啟用它，然後才能運行Python指令碼。
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無法直接在CLI中建立Python指令碼；它們需要首先在開發環境中開發，然後複製到交換機的快閃記憶體中。
Cisco IOS XE中的SELinux
從Cisco IOS XE 17.8.1開始，引入了對安全增強型Linux(SELinux)的支援，以通過管理進程、使用者和檔案相互互動方式的策略來實施安全。SELinux策略定義允許進程或使用者訪問哪些操作和資源。當使用者或進程嘗試執行策略不允許的操作（例如訪問資源或運行命令）時，可能會發生衝突。SELinux可以在兩種不同模式下運行：
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允許模式：SELinux不會實施任何策略。但是，它仍會記錄任何違規行為，好像這些行為被拒絕一樣。
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實施：SELinux會在系統上主動實施安全策略。如果操作違反了SELinux策略，則拒絕並記錄該操作。
附註：在Cisco IOS XE 17.8.1中引入預設模式時，該模式被設定為允許模式。但是，從版本17.14.1開始，SELinux在執行模式下啟用。
使用Guest Shell時，在使用強制模式時可能會拒絕訪問某些資源。如果嘗試使用Guest Shell或Python指令碼執行操作時導致許可權被拒絕錯誤，則與此日誌類似：
*Jan 21 13:22:01: %SELINUX-1-VIOLATION: Chassis 1 R0/0: audispd: type=AVC msg=audit(1738074795.448:198): avc: denied { read } for pid=22604 comm="python3" name="cat9k_python_script.py" dev="sda3" ino=178569 scontext=system_u:system_r:polaris_iox_container_t:s0:c165,c174 tcontext=system_u:object_r:polaris_disk_bootflash_t:s0 tclass=file permissive=0
要驗證SELinux是否拒絕指令碼，請使用命令show platform software audit summary檢查「拒絕計數」是否增加。此外show platform software audit all，還會顯示被SELinux阻止的操作的日誌。訪問向量快取(AVC)是用於記錄SELinux中的訪問控制決策的機制，因此，使用此命令時，請查詢以type=AVC開頭的日誌。
如果指令碼被拒絕和阻止，則可以使用命令將SELinux設定為允許模式set platform software selinux permissive。此變更不會儲存在執行或啟動組態中，因此重新載入後，模式會回覆為強制執行。因此，每次重新載入交換機時，都需要重新應用此更改。可以使用驗證更改show platform software selinux。
設定
要使用EEM和Python指令碼自動執行交換機上的任務，請執行以下步驟：
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啟用Guest Shell。
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將Python指令碼複製到/flash/guest-share/目錄。您可以使用Cisco IOS XE中可用的任何複製機制，例如SCP、FTP或WebUI中的File Manager。Python指令碼在快閃記憶體中後，可以使用命令
guestshell run python3 /flash/guest-share/cat9k_script.py運行該指令碼。 -
配置運行Python腳本的EEM指令碼。此設定允許使用EEM指令碼提供的任意多個事件檢測器（如系統日誌消息、CLI模式和Cron排程程式）觸發Python指令碼。
本節將介紹步驟1。下一部分提供了演示如何實施步驟2和步驟3的示例。
使用靜態IP地址啟用來賓外殼
按照以下過程啟用訪客外殼：
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啟用IOx。
Switch#conf t Switch(config)#iox Switch(config)# *Feb 17 18:13:24.440: %UICFGEXP-6-SERVER_NOTIFIED_START: Switch 1 R0/0: psd: Server iox has been notified to start *Feb 17 18:13:28.797: %IOX-3-IOX_RESTARTABITLITY: Switch 1 R0/0: run_ioxn_caf: Stack is in N+1 mode, disabling sync for IOx restartabilityapp- *Feb 17 18:13:36.069: %IM-6-IOX_ENABLEMENT: Switch 1 R0/0: ioxman: IOX is ready.
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為訪客Shell配置應用宿主網路。此示例使用AppGigabitEthernet介面提供網路訪問；但是，也可以使用管理介面(Gi0/0)。
Switch(config)#int appgig1/0/1 Switch(config-if)#switchport mode trunk Switch(config-if)#switchport trunk allowed vlan 20 Switch(config)#app-hosting appid guestshell Switch(config-app-hosting)#app-vnic appGigabitEthernet trunk Switch(config-config-app-hosting-trunk)#vlan 20 guest-interface 0 Switch(config-config-app-hosting-vlan-access-ip)#guest-ipaddress 10.20.1.2 netmask 255.255.255.0 Switch(config-config-app-hosting-vlan-access-ip)#exit Switch(config-config-app-hosting-trunk)#exit Switch(config-app-hosting)#app-default-gateway 10.20.1.1 guest-interface 0 Switch(config-app-hosting)#name-server0 10.31.104.74
Switch(config-app-hosting)#end -
啟用Guest Shell。
Switch#guestshell enable Interface will be selected if configured in app-hosting Please wait for completion guestshell installed successfully Current state is: DEPLOYED guestshell activated successfully Current state is: ACTIVATED guestshell started successfully Current state is: RUNNING Guestshell enabled successfully
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驗證Guest Shell。此範例驗證預設閘道與cisco.com是否可連線。此外，驗證Python 3是否可從訪客外殼運行。
! Validate that the Guest Shell is running.
Switch#show app-hosting list App id State --------------------------------------------------------- guestshell RUNNING Switch#guestshell run bash [guestshell@guestshell ~]$
! Validate that the IP address of the Guest Shell is configured correctly. [guestshell@guestshell ~]$ sudo ifconfig eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.20.1.2 netmask 255.255.255.0 broadcast 10.20.1.255 inet6 fe80::5054:ddff:fe61:24c7 prefixlen 64 scopeid 0x20 ether 52:54:dd:61:24:c7 txqueuelen 1000 (Ethernet) RX packets 23 bytes 1524 (1.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 9 bytes 726 (726.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 177 bytes 34754 (33.9 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 177 bytes 34754 (33.9 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ! Validate reachability to the default gateway and ensure that DNS is resolving correctly. [guestshell@guestshell ~]$ ping 10.20.1.1 PING 10.20.1.1 (10.20.1.1) 56(84) bytes of data. 64 bytes from 10.20.1.1: icmp_seq=2 ttl=254 time=0.537 ms 64 bytes from 10.20.1.1: icmp_seq=3 ttl=254 time=0.537 ms 64 bytes from 10.20.1.1: icmp_seq=4 ttl=254 time=0.532 ms 64 bytes from 10.20.1.1: icmp_seq=5 ttl=254 time=0.574 ms 64 bytes from 10.20.1.1: icmp_seq=6 ttl=254 time=0.590 ms ^C --- 10.20.1.1 ping statistics --- 6 packets transmitted, 5 received, 16.6667% packet loss, time 5129ms rtt min/avg/max/mdev = 0.532/0.554/0.590/0.023 ms [guestshell@guestshell ~]$ ping cisco.com PING cisco.com (X.X.X.X) 56(84) bytes of data. 64 bytes from www1.cisco.com (X.X.X.X): icmp_seq=1 ttl=237 time=125 ms 64 bytes from www1.cisco.com (X.X.X.X): icmp_seq=2 ttl=237 time=125 ms ^C --- cisco.com ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1002ms rtt min/avg/max/mdev = 124.937/125.141/125.345/0.204 ms ! Validate the Python version. [guestshell@guestshell ~]$ python3 --version Python 3.6.8
! Run Python commands within the Guest Shell. [guestshell@guestshell ~]$ python3 Python 3.6.8 (default, Dec 22 2020, 19:04:08) [GCC 8.4.1 20200928 (Red Hat 8.4.1-1)] on linux Type "help", "copyright", "credits" or "license" for more information. >>> print("Cisco") Cisco >>> exit() [guestshell@guestshell ~]$ [guestshell@guestshell ~]$ exit exit Switch#
使用DHCP IP地址啟用來賓外殼
通常，訪客Shell配置有靜態IP地址，因為預設情況下Guest Shell容器沒有DHCP客戶端服務。如果訪客外殼需要動態請求IP地址，則需要安裝DHCP客戶端服務。請遵循以下流程：
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按照以下步驟啟用具有靜態IP地址的來賓外殼。但是，這一次，請勿在步驟2中分配應用託管配置中的IP地址。請改用以下配置：
Switch(config)#int appgig1/0/1 Switch(config-if)#switchport mode trunk Switch(config-if)#switchport trunk allowed vlan 20 Switch(config)#app-hosting appid guestshell Switch(config-app-hosting)#app-vnic appGigabitEthernet trunk Switch(config-config-app-hosting-trunk)#vlan 20 guest-interface 0 Switch(config-app-hosting)#end
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可以使用命令
sudo yum install dhcp-client的Yum實用程式安裝DHCP客戶端。然而，CentOS Stream 8的儲存庫已經停用。為了解決此問題，可以手動下載和安裝DHCP客戶端軟體包。在PC上，從CentOS Stream 8 vault下載這些軟體包並將其打包為tar檔案。- bind-export-libs-9.11.36-13.el8.x86_64.rpm
- dhcp-client-4.3.6-50.el8.x86_64.rpm
- dhcp-common-4.3.6-50.el8.noarch.rpm
- dhcp-libs-4.3.6-50.el8.x86_64.rpm
[cisco@CISCO-PC guestshell-packages] % tar -cf dhcp-client.tar bind-export-libs-9.11.36-13.el8.x86_64.rpm dhcp-client-4.3.6-50.el8.x86_64.rpm dhcp-common-4.3.6-50.el8.noarch.rpm dhcp-libs-4.3.6-50.el8.x86_64.rpm
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將檔案
dhcp-client.tar，複製到交換器中的/flash/guest-share/目錄。 -
輸入Guest Shell bash session，然後運行Linux命令以安裝DHCP客戶端並請求IP地址。
513E.D.02-C9300X-12Y-A-17#guestshell run bash [guestshell@guestshell ~]$ sudo ifconfig lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 <--- no eth0 interface inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 149 bytes 32462 (31.7 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 149 bytes 32462 (31.7 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
! Unpack the packages needed for the DHCP client service. [guestshell@guestshell ~]$ tar -xf /flash/guest-share/dhcp-client.tar tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.quarantine' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.metadata:kMDItemWhereFroms' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.macl' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.quarantine' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.metadata:kMDItemWhereFroms' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.macl' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.quarantine' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.metadata:kMDItemWhereFroms' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.macl' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.quarantine' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.metadata:kMDItemWhereFroms' tar: Ignoring unknown extended header keyword 'LIBARCHIVE.xattr.com.apple.macl' [guestshell@guestshell ~]$ ls bind-export-libs-9.11.36-13.el8.x86_64.rpm dhcp-common-4.3.6-50.el8.noarch.rpm dhcp-client-4.3.6-50.el8.x86_64.rpm dhcp-libs-4.3.6-50.el8.x86_64.rpm
! Install the packages using DNF. [guestshell@guestshell ~]$ sudo dnf -y --disablerepo=* localinstall *.rpm Warning: failed loading '/etc/yum.repos.d/CentOS-Base.repo', skipping. Dependencies resolved. ==================================================================================================== Package Architecture Version Repository Size ==================================================================================================== Installing: bind-export-libs x86_64 32:9.11.36-13.el8 @commandline 1.1 M dhcp-client x86_64 12:4.3.6-50.el8 @commandline 319 k dhcp-common noarch 12:4.3.6-50.el8 @commandline 208 k dhcp-libs x86_64 12:4.3.6-50.el8 @commandline 148 k Transaction Summary ==================================================================================================== Install 4 Packages Total size: 1.8 M Installed size: 3.9 M Downloading Packages: Running transaction check Transaction check succeeded. Running transaction test Transaction test succeeded. Running transaction Preparing : 1/1 Installing : dhcp-libs-12:4.3.6-50.el8.x86_64 1/4 Installing : dhcp-common-12:4.3.6-50.el8.noarch 2/4 Installing : bind-export-libs-32:9.11.36-13.el8.x86_64 3/4 Running scriptlet: bind-export-libs-32:9.11.36-13.el8.x86_64 3/4 Installing : dhcp-client-12:4.3.6-50.el8.x86_64 4/4 Running scriptlet: dhcp-client-12:4.3.6-50.el8.x86_64 4/4 Verifying : bind-export-libs-32:9.11.36-13.el8.x86_64 1/4 Verifying : dhcp-client-12:4.3.6-50.el8.x86_64 2/4 Verifying : dhcp-common-12:4.3.6-50.el8.noarch 3/4 Verifying : dhcp-libs-12:4.3.6-50.el8.x86_64 4/4 Installed: bind-export-libs-32:9.11.36-13.el8.x86_64 dhcp-client-12:4.3.6-50.el8.x86_64 dhcp-common-12:4.3.6-50.el8.noarch dhcp-libs-12:4.3.6-50.el8.x86_64 Complete!
! Request a DHCP IP address for eth0. [guestshell@guestshell ~]$ sudo dhclient eth0
! Validate the leased IP address. [guestshell@guestshell ~]$ sudo ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.1.1.12 netmask 255.255.255.0 broadcast 10.1.1.255 inet6 fe80::5054:ddff:fe85:a0d5 prefixlen 64 scopeid 0x20 ether 52:54:dd:85:a0:d5 txqueuelen 1000 (Ethernet) RX packets 7 bytes 1000 (1000.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 11 bytes 1354 (1.3 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [guestshell@guestshell ~]$ exit exit
! You can validate the leased IP address from Cisco IOS XE too. 513E.D.02-C9300X-12Y-A-17#guestshell run sudo ifconfig eth0 eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.1.1.12 netmask 255.255.255.0 broadcast 10.1.1.255 inet6 fe80::5054:ddff:fe85:a0d5 prefixlen 64 scopeid 0x20 ether 52:54:dd:85:a0:d5 txqueuelen 1000 (Ethernet) RX packets 28 bytes 2344 (2.2 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 13 bytes 1494 (1.4 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
使用案例
使用案例1:在SCP伺服器上自動儲存配置更改
write memory 在某些情況下，每次使用命令時自動將交換機配置儲存到服務器是有益的。這種做法有助於維護更改記錄，並在必要時允許配置回滾。選擇伺服器時，可以使用TFTP和SCP，但SCP伺服器可提供額外的安全層。
Cisco IOS存檔功能提供此功能。但是，一個重大缺點是配置中不能隱藏SCP憑證；伺服器路徑在運行配置和啟動配置中均以純文字檔案顯示。
Switch#show running-config | section archive
archive
path scp://cisco:Cisco!123@10.31.121.224/
write-memory
通過使用Guest Shell和Python，可以在保持憑證隱藏的同時實現相同的功能。這是通過利用訪客Shell中的環境變數儲存實際SCP憑據來實現的。因此，SCP伺服器憑據在運行配置中不可見。
在此方法中，運行配置僅顯示EEM指令碼，而Python指令碼使用憑證構建命令copy running-config scp:，並將其傳遞給要運行的EEM指令碼。
請依照以下步驟操作本範例：
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將Python指令碼複製到/flash/guest-share目錄。此指令碼讀取環境變數SCP_USER和SCP_PASSWORD，並返回
copy startup-config scp:命令，以便EEM指令碼可以運行它。指令碼需要SCP伺服器IP地址作為引數。此外，指令碼會維護每次在位於/flash/guest-share/TAC-write-memory-log.txt的永久文件中運行命令時的日誌write memory。以下是Python指令碼：import sys import os import cli from datetime import datetime # Get SCP server from the command-line argument (first argument passed) scp_server = sys.argv[1] # Expects the SCP server address as the first argument # Configure CLI to suppress file prompts (quiet mode) cli.configure("file prompt quiet") # Get the current date and time current_time = datetime.now() # Format the current time for human-readable output and to use in filenames formatted_time = current_time.strftime("%Y-%m-%d %H:%M:%S %Z") # e.g., 2025-03-13 14:30:00 UTC file_name_time = current_time.strftime("%Y-%m-%d_%H_%M_%S") # e.g., 2025-03-13_14_30_00 # Retrieve SCP user and password from environment variables securely scp_user = os.getenv('SCP_USER') # SCP username from environment scp_password = os.getenv('SCP_PASSWORD') # SCP password from environment # Ensure the credentials are set in the environment, raise error if missing if not scp_user or not scp_password: raise ValueError("SCP user or password not found in environment variables!") # Construct the SCP command to copy the file, avoiding exposure of sensitive data in print # WARNING: The password should not be shared openly in logs or outputs. print(f"copy startup-config scp://{scp_user}:{scp_password}@{scp_server}/config-backup-{file_name_time}.txt") # Save the event in flash memory (log the write operation) directory = '/flash/guest-share' # Directory path where log will be saved file_name = os.path.join(directory, 'TAC-write-memory-log.txt') # Full path to log file # Prepare the log entry with the formatted timestamp line = f'{formatted_time}: Write memory operation.\n' # Open the log file in append mode to add the new log entry with open(file_name, 'a') as file: file.write(line) # Append the log entry to the file在以下範例中，使用TFTP伺服器將Python指令碼複製到交換器：
Switch#copy tftp://10.207.204.10/cat9k_scp_command.py flash:/guest-share/cat9k_scp_command.py
Accessing tftp://10.207.204.10/cat9k_scp_command.py...
Loading cat9k_scp_command.py from 10.207.204.10 (via GigabitEthernet0/0): !
[OK - 917 bytes]
917 bytes copied in 0.017 secs (53941 bytes/sec) -
安裝EEM指令碼。此指令碼呼叫Python指令碼。返回在SCP伺服器上儲存配置所需的命令
copy startup-config scp:。然後，EEM指令碼運行Python指令碼返回的命令。event manager applet Python-config-backup authorization bypass event cli pattern "^write|write memory|copy running-config startup-config" sync no skip no maxrun 60 action 0000 syslog msg "Config save detected, TAC EEM-python started." action 0005 cli command "enable" action 0015 cli command "guestshell run python3 /bootflash/guest-share/cat9k_scp_command.py 10.31.121.224" action 0020 regexp "(^.*)\n" "$_cli_result" match command action 0025 cli command "$command" action 0030 syslog msg "TAC EEM-python script finished with result: $_cli_result"
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將Guest Shell環境變數插入到檔案中來設定這些
~/.bashrc變數。這可確保每次開啟訪客Shell時環境變數都是持久的，即使在重新載入交換機後也是如此。新增以下兩行：export SCP_USER="cisco" export SCP_PASSWORD="Cisco!123"
注意：本示例中使用的憑據僅用於教育目的。它們不能用於生產環境。使用者需要用他們自己的安全、特定於環境的憑據替換這些憑據。
這是將這些變數新增到檔案的過程
~/.bashrc:! 1. Enter a Guest Shell bash session.
Switch#guestshell run bash
! 2. Locate the ~/.bashrc file. [guestshell@guestshell ~]$ ls ~/.bashrc /home/guestshell/.bashrc
! 3. Add the SCP_USER and SCP_PASSWORD environment variables at the end of the ~/.bashrc file. [guestshell@guestshell ~]$ echo 'export SCP_USER="cisco"' >> ~/.bashrc
[guestshell@guestshell ~]$ echo 'export SCP_PASSWORD="Cisco!123"' >> ~/.bashrc
! 4. To validate these 2 new lines were added correctly, display the content of the ~/.bashrc file. [guestshell@guestshell ~]$ cat ~/.bashrc # .bashrc # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi # User specific environment if ! [[ "$PATH" =~ "$HOME/.local/bin:$HOME/bin:" ]] then PATH="$HOME/.local/bin:$HOME/bin:$PATH" fi export PATH # Uncomment the following line if you don't like systemctl's auto-paging feature: # export SYSTEMD_PAGER= # User specific aliases and functions [guestshell@guestshell ~]$ echo 'export SCP_USER="cisco"' >> ~/.bashrc [guestshell@guestshell ~]$ echo 'export SCP_PASSWORD="Cisco!123"' >> ~/.bashrc [guestshell@guestshell ~]$ cat ~/.bashrc # .bashrc # Source global definitions if [ -f /etc/bashrc ]; then . /etc/bashrc fi # User specific environment if ! [[ "$PATH" =~ "$HOME/.local/bin:$HOME/bin:" ]] then PATH="$HOME/.local/bin:$HOME/bin:$PATH" fi export PATH # Uncomment the following line if you don't like systemctl's auto-paging feature: # export SYSTEMD_PAGER= # User specific aliases and functions export SCP_USER="cisco" export SCP_PASSWORD="Cisco!123" ! 5. Reload the ~/.bashrc file in the current session. [guestshell@guestshell ~]$ source ~/.bashrc
! 6. Validate that the environment variables are added, then exit the Guest Shell session. [guestshell@guestshell ~]$ printenv | grep SCP SCP_USER=cisco SCP_PASSWORD=Cisco!123 [guestshell@guestshell ~]$ exit Switch# -
手動運行Python指令碼，以驗證它是否返回正確的命令
copy，並將操作記錄在持久檔案TAC-write-memory-log.txt中。Switch#guestshell run python3 /flash/guest-share/cat9k_scp_command.py 10.31.121.224 copy startup-config scp://cisco:Cisco!123@10.31.121.224/config-backup-2025-01-25_18_35_18.txt Switch#dir flash:guest-share/ Directory of flash:guest-share/ 286725 -rw- 368 Jan 25 2025 18:35:18 +00:00 TAC-write-memory-log.txt 286726 -rw- 903 Jan 25 2025 18:34:45 +00:00 cat9k_scp_command.py 286723 -rw- 144 Jan 25 2025 15:07:07 +00:00 TAC-shutdown-log.txt 286722 -rw- 977 Jan 25 2025 14:50:56 +00:00 cat9k_noshut.py 11353194496 bytes total (3751542784 bytes free) Switch#more flash:/guest-share/TAC-write-memory-log.txt 2025-01-25 18:35:18 : Write memory operation.
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測試EEM指令碼。此EEM指令碼還會傳送包含複製操作結果的系統日誌，無論複製操作成功還是失敗。以下是成功執行的範例：
Switch#write memory Building configuration... [OK] Switch# *Jan 25 19:23:22.189: %HA_EM-6-LOG: Python-config-backup: Config save detected, TAC EEM-python started. *Jan 25 19:23:42.885: %HA_EM-6-LOG: Python-config-backup: TAC EEM-python script finished with result: Writing config-backup-2025-01-25_19_23_26.txt ! 8746 bytes copied in 15.175 secs (576 bytes/sec) Switch# Switch#more flash:guest-share/TAC-write-memory-log.txt 2025-01-25 19:23:26 : Write memory operation.
要測試失敗的傳輸，SCP伺服器將關閉。這是此失敗運行的結果：
Switch#write Building configuration... [OK] Switch# *Jan 25 19:25:31.439: %HA_EM-6-LOG: Python-config-backup: Config save detected, TAC EEM-python started. *Jan 25 19:26:06.934: %HA_EM-6-LOG: Python-config-backup: TAC EEM-python script finished with result: Writing config-backup-2025-01-25_19_25_36.txt % Connection timed out; remote host not responding %Error writing scp://*:*@10.31.121.224/config-backup-2025-01-25_19_25_36.txt (Undefined error) Switch# Switch# Switch# Switch#more flash:guest-share/TAC-write-memory-log.txt 2025-01-25 19:23:26 : Write memory operation. 2025-01-25 19:25:36 : Write memory operation.
使用案例2:監控STP拓撲更改的增量
此示例對於監控與生成樹不穩定相關的問題，以及確定哪個介面正在接收拓撲更改通知(TCN)非常有用。 EEM指令碼以指定的時間間隔定期運行，並呼叫運行show命令並檢查TCN是否增加的Python指令碼。
僅使用EEM命令建立此指令碼需要用於循環和多個正規表示式匹配，這將非常麻煩。因此，此示例展示EEM指令碼如何將此複雜邏輯委託給Python。
請依照以下步驟操作本範例：
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將Python指令碼複製到/flash/guest-share/目錄。此指令碼執行以下任務：
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它會運行
show spanning-tree detail命令並解析輸出，以便將每個VLAN的TCN資訊儲存在字典中。 -
它將分析的TCN資訊與上次運行指令碼的JSON檔案中的資料進行比較。如果每個VLAN的TCN都增加了，系統就會傳送包含類似以下示例的資訊的syslog消息：
*Jan 31 18:57:37.852: %GUESTSHELL-5-PYTHON_SCRIPT: Message from tty73(user id: shxUnknownTTY): TCNs increased in VLAN 0010 from 57 to 58. Last TCN seen on FiveGigabitEthernet1/0/48.
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它將當前TCN資訊儲存在JSON檔案中，以便在下次運行期間進行比較。以下是Python指令碼：
import os import json import cli import re from datetime import datetime def main(): # Get TCNs by running the CLI command to show spanning tree details tcns = cli.cli("show spanning-tree detail") # Parse the output into a dictionary of VLAN details parsed_tcns = parse_stp_detail(tcns) # Path to the JSON file where VLAN TCN data will be stored file_path = '/flash/guest-share/tcns.json' # Initialize an empty dictionary to hold stored TCN data stored_tcn = {} # Check if the file exists and process it if it does if os.path.exists(file_path): try: # Open the JSON file and parse its contents into stored_tcn with open(file_path, 'r') as f: stored_tcn = json.load(f) result = compare_tcn_sets(stored_tcn, parsed_tcns) # Check each VLAN in the result and log changes if TCN increased for vlan_id, vlan_data in result.items(): if vlan_data['tcn_increased']: log_message = ( f"TCNs increased in VLAN {vlan_id} " f"from {vlan_data['old_tcn']} to {vlan_data['new_tcn']}. " f"Last TCN seen on {vlan_data['source_interface']}." ) # Send log message using CLI cli.cli(f"send log facility GUESTSHELL severity 5 mnemonics PYTHON_SCRIPT {log_message}") except json.JSONDecodeError: print("Error: The file contains invalid JSON.") except Exception as e: print(f"An error occurred: {e}") # Write the current TCN data to the JSON file for future comparison with open(file_path, 'w') as f: json.dump(parsed_tcns, f, indent=4) def parse_stp_detail(cli_output: str): """ Parses the output of "show spanning-tree detail" into a dictionary of VLANs and their TCN info. Args: cli_output (str): The raw output from the "show spanning-tree detail" command. Returns: dict: A dictionary where the keys are VLAN IDs and the values contain TCN details. """ vlan_info = {} # Regular expressions to match various parts of the "show spanning-tree detail" output vlan_pattern = re.compile(r'^\s*(VLAN|MST)(\d+)\s*', re.MULTILINE) tcn_pattern = re.compile(r'^\s*Number of topology changes (\d+)\s*', re.MULTILINE) last_tcn_pattern = re.compile(r'last change occurred (\d+:\d+:\d+) ago\s*', re.MULTILINE) last_tcn_days_pattern = re.compile(r'last change occurred (\d+d\d+h) ago\s*', re.MULTILINE) tcn_interface_pattern = re.compile(r'from ([a-zA-Z]+[\d+\/]+\d+)\s*', re.MULTILINE) # Find all VLAN blocks in the output vlan_blocks = vlan_pattern.split(cli_output)[1:] vlan_blocks = [item for item in vlan_blocks if item not in ["VLAN", "MST"]] for i in range(0, len(vlan_blocks), 2): vlan_id = vlan_blocks[i].strip() # Match the relevant patterns for TCN and related details tcn_match = tcn_pattern.search(vlan_blocks[i + 1]) last_tcn_match = last_tcn_pattern.search(vlan_blocks[i + 1]) last_tcn_days_match = last_tcn_days_pattern.search(vlan_blocks[i + 1]) tcn_interface_match = tcn_interface_pattern.search(vlan_blocks[i + 1]) # Parse the TCN details and add to the dictionary if last_tcn_match: tcn = int(tcn_match.group(1)) last_tcn = last_tcn_match.group(1) source_interface = tcn_interface_match.group(1) if tcn_interface_match else None vlan_info[vlan_id] = { "id_int": int(vlan_id), "tcn": tcn, "last_tcn": last_tcn, "source_interface": source_interface, "tcn_in_last_day": True } elif last_tcn_days_match: tcn = int(tcn_match.group(1)) last_tcn = last_tcn_days_match.group(1) source_interface = tcn_interface_match.group(1) if tcn_interface_match else None vlan_info[vlan_id] = { "id_int": int(vlan_id), "tcn": tcn, "last_tcn": last_tcn, "source_interface": source_interface, "tcn_in_last_day": False } return vlan_info def compare_tcn_sets(set1, set2): """ Compares two sets of VLAN TCN data to determine if TCN values have increased. Args: set1 (dict): The first set of VLAN TCN data. set2 (dict): The second set of VLAN TCN data. Returns: dict: A dictionary indicating whether the TCN has increased for each VLAN. """ tcn_changes = {} # Compare TCN values for VLANs that exist in both sets for vlan_id, vlan_data_1 in set1.items(): if vlan_id in set2: vlan_data_2 = set2[vlan_id] tcn_increased = vlan_data_2['tcn'] > vlan_data_1['tcn'] tcn_changes[vlan_id] = { 'tcn_increased': tcn_increased, 'old_tcn': vlan_data_1['tcn'], 'new_tcn': vlan_data_2['tcn'], 'source_interface': vlan_data_2['source_interface'] } else: tcn_changes[vlan_id] = { 'tcn_increased': None, # No comparison if VLAN is not in set2 'old_tcn': vlan_data_1['tcn'], 'new_tcn': None } # Check for VLANs in set2 that are not in set1 for vlan_id, vlan_data_2 in set2.items(): if vlan_id not in set1: tcn_changes[vlan_id] = { 'tcn_increased': None, # No comparison if VLAN is not in set1 'old_tcn': None, 'new_tcn': vlan_data_2['tcn'] } return tcn_changes if __name__ == "__main__": main()在以下範例中，使用TFTP伺服器將Python指令碼複製到交換器：
Switch#copy tftp://10.207.204.10/cat9k_tcn.py flash:/guest-share/cat9k_tcn.py Accessing tftp://10.207.204.10/cat9k_tcn.py... Loading cat9k_tcn.py from 10.207.204.10 (via GigabitEthernet0/0): ! [OK - 5739 bytes] 5739 bytes copied in 0.023 secs (249522 bytes/sec)
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安裝EEM指令碼。在此示例中，EEM指令碼的唯一任務是運行Python指令碼，該指令碼在檢測到TCN增量時傳送日誌消息。在此示例中，EEM指令碼每5分鐘運行一次。
event manager applet tcn_monitor authorization bypass event timer watchdog time 300 action 0000 syslog msg "TAC EEM-python script started." action 0005 cli command "enable" action 0015 cli command "guestshell run python3 /bootflash/guest-share/cat9k_tcn.py" action 0020 syslog msg "TAC EEM-python script finished."
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要驗證指令碼的功能，您可以手動運行Python指令碼，或者等待5分鐘以讓EEM指令碼呼叫該指令碼。在這兩種情況下，系統日誌僅在某個VLAN的TCN增加時才傳送。
Switch#more flash:/guest-share/tcns.json
{
"0001": {
"id_int": 1,
"tcn": 20,
"last_tcn": "00:01:18",
"source_interface": "TwentyFiveGigE1/0/5",
"tcn_in_last_day": true
},
"0010": {
"id_int": 10,
"tcn": 2,
"last_tcn": "00:00:22",
"source_interface": "TwentyFiveGigE1/0/1",
"tcn_in_last_day": true
},
"0020": {
"id_int": 20,
"tcn": 2,
"last_tcn": "00:01:07",
"source_interface": "TwentyFiveGigE1/0/2",
"tcn_in_last_day": true
},
"0030": {
"id_int": 30,
"tcn": 1,
"last_tcn": "00:01:18",
"source_interface": "TwentyFiveGigE1/0/3",
"tcn_in_last_day": true
}
}
Switch#guestshell run python3 /flash/guest-share/cat9k_tcn.py Switch# *Feb 17 21:34:45.846: %GUESTSHELL-5-PYTHON_SCRIPT: Message from tty73(user id: shxUnknownTTY): TCNs increased in VLAN 0030 from 1 to 3. Last TCN seen on TwentyFiveGigE1/0/3. Switch# -
通過等待EEM指令碼每五分鐘運行一次來測試該指令碼。如果任何VLAN的TCN都增加了，則會傳送系統日誌消息。在此特定範例中，請注意VLAN 30上的TCN不斷增加，而接收這些固定TCN的介面是Twe1/0/3。
*Feb 17 21:56:23.563: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script started. *Feb 17 21:56:26.039: %GUESTSHELL-5-PYTHON_SCRIPT: Message from tty73(user id: shxUnknownTTY): TCNs increased in VLAN 0030 from 3 to 5. Last TCN seen on TwentyFiveGigE1/0/3. *Feb 17 21:56:26.585: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script finished. *Feb 17 22:01:23.563: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script started. *Feb 17 22:01:26.687: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script finished. *Feb 17 22:06:23.564: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script started. *Feb 17 22:06:26.200: %GUESTSHELL-5-PYTHON_SCRIPT: Message from tty73(user id: shxUnknownTTY): TCNs increased in VLAN 0030 from 5 to 9. Last TCN seen on TwentyFiveGigE1/0/3. *Feb 17 22:06:26.787: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script finished. *Feb 17 22:11:23.564: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script started. *Feb 17 22:11:26.079: %GUESTSHELL-5-PYTHON_SCRIPT: Message from tty73(user id: shxUnknownTTY): TCNs increased in VLAN 0030 from 9 to 12. Last TCN seen on TwentyFiveGigE1/0/3. *Feb 17 22:11:26.686: %HA_EM-6-LOG: tcn_monitor: TAC EEM-python script finished.
相關資訊
修訂記錄
| 修訂 | 發佈日期 | 意見 |
|---|---|---|
1.0 |
17-Mar-2025
|
初始版本 |
意見