How do I tell if my container is running inside a Kubernetes cluster?

Question

How can I tell whether or not I am running inside a kubernetes cluster? With docker I can check if /.dockerinit exist. Is there an equivalent?

Answer 1

With the default configuration, Kubernetes will mount the serviceaccount secrets into pods. Simply check for the existence of this folder: /var/run/secrets/kubernetes.io. No need to set environment variables. In ruby I would do the following:

if File.exists?('/.dockerenv')
  puts "I'm running in a docker container"
end

if File.exists?('/var/run/secrets/kubernetes.io')
  puts "I'm also running in a Kubernetes pod"
end