You are talking to a gVisor sandbox

This page is served by a pod running under the gVisor runtime (runtimeClassName: gvisor) on an F5 Distributed Cloud Customer Edge, reached through a CE-advertised load balancer.

What kernel is this app running on?

uname -a inside this container:
Linux gvisor-echo-6c4b54f4d8-pp6jc 4.19.0-gvisor #1 SMP Sun Jan 10 15:06:54 PST 2016 x86_64 GNU/Linux
The CE host actually runs Linux 5.14 (RHEL 9). This container sees 4.19.0-gvisor - a different kernel, because gVisor gave it one of its own.

Why that matters

A normal container (runc) shares the host Linux kernel directly. Run uname -r in a runc container on this same CE and you would see the host 5.14 kernel - the app is one kernel CVE or container escape away from the host.

Under gVisor the container gets its own kernel, implemented in userspace - the gVisor Sentry. Every system call this app makes is intercepted and re-interpreted by the Sentry; the host kernel is never directly exposed. A kernel exploit, a fork bomb, a namespace escape - it stays inside the sandbox. That is the point of gVisor: a real isolation boundary for untrusted workloads, such as AI agents running generated code.

Proof you are inside gVisor

/proc/version:
Linux version 4.19.0-gvisor #1 SMP Sun Jan 10 15:06:54 PST 2016
/proc/sentry-meminfo: present - a proc entry that exists only inside a gVisor Sentry.
/proc/cpuinfo model name: unknown - gVisor synthesizes CPU info; the real host CPU model is not passed through.

gVisor boot log (dmesg)

The gVisor Sentry boots a kernel in userspace. Its dmesg is unmistakable:

[   0.000000] Starting gVisor...
[   0.386030] Politicking the oom killer...
[   0.493801] Searching for socket adapter...
[   0.506404] Adversarially training Redcode AI...
[   0.794459] Recruiting cron-ies...
[   1.257314] Checking naughty and nice process list...
[   1.578987] Waiting for children...
[   1.635189] Verifying that no non-zero bytes made their way into /dev/zero...
[   1.646236] Daemonizing children...
[   1.910864] Creating cloned children...
[   2.305204] Creating process schedule...
[   2.568321] Ready!

busybox httpd in a gVisor sandbox - F5 ADSP edge AI gateway PoC.