How to determine the OS version using pvymomi? - python-3.x

Question

Using pvymomi, I can determine the OS. How does one determine the OS version?
#!/usr/bin/python3
import sys
import atexit
from pyVmomi import vim
from pyVim.connect import SmartConnectNoSSL, Disconnect
si = SmartConnectNoSSL(host = 'xxx', user = 'xxx', pwd = 'xxx', port = 443)
atexit.register(Disconnect, si)
content = si.RetrieveContent()
vm = si.content.searchIndex.FindByIp(None, sys.argv[1], True)
print(vm.summary.config.guestFullName)
print(vm.summary.config.guestId)
The above code produces the following:
$ ./example.py 10.120.73.45
CentOS 7 (64-bit)
centos7_64Guest
I can see the VM is running CentOS 7, but is it 7.6 or 7.9? I'm not seeing what property or even what data object gives that information.

Answer 1

After doing some research into this question, I have found that the vSphere Web Services API, which the Python package pyvmomi uses does not have an easy way to collect the exact version operating system version with a basic API call.
If you look at the vSphere Web Services API information for
guestFamily, which is in GuestInfo you will not see any API call for precise versioning information.
Additionally, to obtain the exact operating system version information for CentOS you would normally have to query the kernel, which contains this information.
You can obtain the version of CentOS using this command:
cat /etc/centos-release
# output
CentOS Linux release 7.9.2009 (Core)
You can query this information GuestProgramSpec
Here is some pseudocode for doing this.
ps = vim.vm.guest.ProcessManager.ProgramSpec(programPath="/usr/bin/cat", arguments=" /etc/centos-release > /tmp/os_version_info.txt")
res = pm.StartProgramInGuest(vm, creds, ps)
You can also obtain this information using the uname tool, which is commonly used to obtain information about the processor architecture, which as the system hostname and the version of the kernel running on the system.
Here is the command - uname -s -r
-s, (--kernel-name) - Prints the kernel name
-r, (--kernel-release) - Prints the kernel release.
Here is a website that provides some information on mapping the kernel releases information to a specific operating system. Here is another website. Using the latter website I can see that kernel-3.10.0-1160.el7.x86_64 maps to CentOS 7.9.2009 for x86_64.
Here is some pseudocode for doing this.
ps = vim.vm.guest.ProcessManager.ProgramSpec(programPath="/usr/bin/uname", arguments=" -s -r > /tmp/os_kernel_info.txt")
res = pm.StartProgramInGuest(vm, creds, ps)
Based on my research getting this information back to the console is more complex. Here is a Stack Overflow question in how to do this.
UPDATE
I discovered this sample pyvmomi script, which can execute a command and retrieve the content back to the console.
Execute program in a virtual machine