How we can change OS for Google App Engine flexible? Or can we do this at all?

The one I always ends with is:

Linux gae-default-1-c9cf 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u2 (2016-10-19) x86_64

but I need some another version with glibc 2.14.

The current’s one glibc is 2.13:

ldd (Debian EGLIBC 2.13-38+deb7u11) 2.13

And I can’t upgrade glibc on this OS, because after apt-get update and apt-get install libc6 I getting this:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
libc6 is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 5 not upgraded.

And I can’t modify sources.list because of:

-bash: /etc/apt/sources.list: Permission denied

So all I need is another OS for my GAE flexible app. Is that possible?

Answer

Yes, you can build a custom dockerfile either by referring one which fits your requirements or specifying it from scratch: Building Custom Runtimes