In #15537 we implemented a kubernetes detector based on an env var pattern. But 99.99% of the time KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT will be defined, and they can be looked up quickly without looping around the enumerable property source. The negative case, unfortunately, remains inefficient.
Comment From: dsyer
https://stackoverflow.com/a/54130803/1368236
I like this one:
if File.exists?('/var/run/secrets/kubernetes.io')
puts "I'm also running in a Kubernetes pod"
end
That's cheap and efficient.
Probably. I guess if /var/run/secrets exists and is network attached it might be slow.
Comment From: philwebb
Thomas Risberg also suggested /var/run/secrets/kubernetes.io/serviceaccount/namespace that even gives you the namespace
https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#accessing-the-api-from-a-pod
Comment From: dsyer
The namespace is handy if you are going to use the k8s API, but for the purpose of this issue (the @Condition which for sure has no business making API calls) it’s not relevant, I would say. IMO we should check the specific env var, then the file, and then maybe (or maybe not - I really think it should be optional), check all the env vars for a pattern match. Possibly some measurements should be made to confirm, but in systems with large numbers of env vars, the fallback to looking at all of them for a pattern match seems like a bad idea.
Comment From: mbhave
Closing in favor of PR #19002.