Both AWS and GCP, probably Azure as well, offer the ability to query instance level metadata from within the guest (and container)
https://cloud.google.com/compute/docs/storing-retrieving-metadata#querying
curl "http://metadata.google.internal/computeMetadata/v1/instance"
root@5f9f3662a783:/# curl -vv "http://metadata.google.internal/computeMetadata/v1/instance"
* Trying 169.254.169.254:80...
* TCP_NODELAY set
* Connected to metadata.google.internal (169.254.169.254) port 80 (#0)
> GET /computeMetadata/v1/instance HTTP/1.1
> Host: metadata.google.internal
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Server: BaseHTTP/0.3 Python/2.7.13
< Date: Mon, 10 May 2021 15:55:56 GMT
< Content-Type: application/text
< Metadata-Flavor: Google
<
attributes/
cpu-platform
description
disks/
guest-attributes/
hostname
id
image
legacy-endpoint-access/
licenses/machine-typemaintenance-eventnamenetwork-interfaces/preemptedremaining-cpu-timescheduling/
service-accounts/
tags
virtual-clock/
zone
* Closing connection 0
on AWS, https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html
root@5f9f3662a783:/# curl -vv http://169.254.169.254/latest/meta-data/
* Trying 169.254.169.254:80...
* TCP_NODELAY set
* Connected to 169.254.169.254 (169.254.169.254) port 80 (#0)
> GET /latest/meta-data/ HTTP/1.1
> Host: 169.254.169.254
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
* HTTP 1.0, assume close after body
< HTTP/1.0 404 Not Found
< Server: BaseHTTP/0.3 Python/2.7.13
< Date: Mon, 10 May 2021 15:53:25 GMT
< Content-Type: text/html; charset=UTF-8
< Metadata-Flavor: Google
<
<!DOCTYPE html>
<html lang=en>
<meta charset=utf-8>
<meta name=viewport content="initial-scale=1, minimum-scale=1, width=device-width">
<title>Error 404 (Not Found)!!1</title>
<style>
*{margin:0;padding:0}html,code{font:15px/22px arial,sans-serif}html{background:#fff;color:#222;padding:15px}body{margin:7% auto 0;max-width:390px;min-height:180px;padding:30px 0 15px}* > body{background:url(//www.google.com/images/errors/robot.png) 100% 5px no-repeat;padding-right:205px}p{margin:11px 0 22px;overflow:hidden}ins{color:#777;text-decoration:none}a img{border:0}@media screen and (max-width:772px){body{background:none;margin-top:0;max-width:none;padding-right:0}}#logo{background:url(//www.google.com/images/branding/googlelogo/1x/googlelogo_color_150x54dp.png) no-repeat;margin-left:-5px}@media only screen and (min-resolution:192dpi){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat 0% 0%/100% 100%;-moz-border-image:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) 0}}@media only screen and (-webkit-min-device-pixel-ratio:2){#logo{background:url(//www.google.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png) no-repeat;-webkit-background-size:100% 100%}}#logo{display:inline-block;height:54px;width:150px}
</style>
<a href=//www.google.com/><span id=logo aria-label=Google></span></a>
<p><b>404.</b> <ins>That’s an error.</ins>
<p>The requested URL <code>/latest/meta-data/</code> was not found on this server. <ins>That’s all we know.</ins>
* Closing connection 0