python-os.md

title
Python / OS

Python / OS

Hostname

• 取 hostname 最通用的方法是 socket.gethostname()，雖然 os.uname().nodename 也可以取到一樣的結果，但只適用於 Unix-lie。

• 在 Docker 取用 hostname 時，預設會拿到 container ID：

  $ docker run python:2.7 python -c 'import os, socket; print os.uname(), socket.gethostname()'
  ('Linux', '5744e91eadf5', '4.9.125-linuxkit', '#1 SMP Fri Sep 7 08:20:28 UTC 2018', 'x86_64') 5744e91eadf5
  
  $ docker ps -a | head -2
  CONTAINER ID        IMAGE                                                     COMMAND                  CREATED             STATUS                      PORTS                     NAMES
  5744e91eadf5        python:2.7                                                "python -c 'import o…"   13 seconds ago      Exited (0) 12 seconds ago                             hardcore_panini
  

  但啟動 container 時若有給定 hostname，就可以拿到辦識度比較高的 hostname：

  $ docker run --hostname python-playground python:2.7 python -c 'import os, socket; print os.uname(), socket.gethostname()'
  ('Linux', 'python-playground', '4.9.125-linuxkit', '#1 SMP Fri Sep 7 08:20:28 UTC 2018', 'x86_64') python-playground
  

---

參考資料：

• os.uname() - os — Miscellaneous operating system interfaces — Python 3.7.4rc1 documentation

  • Returns information identifying the current operating system. The return value is an object with five attributes:

    • sysname - operating system name
    • nodename - name of machine on network (IMPLEMENTATION-DEFINED)
    • release - operating system release
    • version - operating system version
    • machine - hardware identifier

    For backwards compatibility, this object is also iterable, behaving like a five-tuple containing sysname, nodename, release, version, and machine in that order.

  • Some systems truncate nodename to 8 characters or to the leading component; a better way to get the hostname is socket.gethostname() or even socket.gethostbyaddr(socket.gethostname()).

    Availability: recent flavors of Unix.

    呼應上面 implementation-defined 的不確定性，加上只有 Unix-like 支援，socket.gethostname() 相較通用。

  • Changed in version 3.3: Return type changed from a tuple to a tuple-like object with named attributes.

• socket.gethostname() - socket — Low-level networking interface — Python 3.7.4rc1 documentation

  • Return a string containing the hostname of the machine where the Python interpreter is currently executing.
  • Note: gethostname() doesn’t always return the fully qualified domain name; use getfqdn() for that.