[Celestica] Make 'sfputil show presence' 10x faster

[dal00]

Why I did it

The is_host function is used when enumerating SFPs which was very slow when detecting if it was running inside docker. The following call makes the detection 10x faster.

How I did it

Instead of executing docker check for /.dockerenv which is present when inside a container.

How to verify it

Before patch:

  $ time sudo sfputil show presence
  Port         Presence
  -----------  -----------
  Ethernet0    Present
  Ethernet1    Present
  Ethernet2    Present

  -- snip --

  real    0m13.521s
  user    0m10.239s
  sys     0m4.104s

After patch:

  $ time sudo sfputil show presence
  Port         Presence
  -----------  -----------
  Ethernet0    Present
  Ethernet1    Present
  Ethernet2    Present

  -- snip --

  real    0m2.133s
  user    0m1.461s
  sys     0m0.347s

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305

Tested branch (Please provide the tested image version)

• 202211

Description for the changelog

n/a

Link to config_db schema for YANG module changes

n/a

A picture of a cute animal (not mandatory but encouraged)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: dal00 / name: Tommy Nevtelen (721fa21)

[dal00]

@lguohan Is there still something needed before this can be reviewed?

[bluecmd]

Ping @lguohan - would be nice to get into the 202411 release if possible.

[bluecmd]

Ping @lguohan - one last attempt before the 202411 release fork happens!

[bradh352]

The only thing I can think of why they haven't merged this is maybe they don't like this change in how the check works for fear issues without Celestica's approval?

Technically the more proper thing to do is look at /proc/1/cgroup and if it's "/" then its the host, otherwise you're running in a container of some sort. But though more proper its probably not as easy to accept as keeping the check the same.

Perhaps more acceptable would be to cache the result instead inside of __init__, so you're actually still using the same container check. Probably rename is_host() to _is_host() to fetch the result and create a new is_host() that just returns the cached variable.