K
Q

Why are my Kubernetes pods sharing environment variables?

11/11/2018

I've got 3, completely distinct, pods:

kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'
kubernetes-bootcamp-5c69669756-5rh9t
queenly-seahorse-mysql-6dc964999c-h4w54
wordpress-mysql-bcc89f687-hs677

but they seem to share the same env vars. E.g.

kubectl exec "kubernetes-bootcamp-5c69669756-5rh9t" env | grep MYSQL
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP=tcp://10.98.170.14:3306
QUEENLY_SEAHORSE_MYSQL_SERVICE_PORT_MYSQL=3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_ADDR=10.98.170.14
QUEENLY_SEAHORSE_MYSQL_SERVICE_HOST=10.98.170.14
QUEENLY_SEAHORSE_MYSQL_SERVICE_PORT=3306
QUEENLY_SEAHORSE_MYSQL_PORT=tcp://10.98.170.14:3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_PORT=3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_PROTO=tcp

and then on a completely different, unrelated pod (but on the same node):

kubectl exec "queenly-seahorse-mysql-6dc964999c-h4w54" env | grep MYSQL
MYSQL_ROOT_PASSWORD=<redact>
MYSQL_PASSWORD=<redact>
MYSQL_USER=
MYSQL_DATABASE=
QUEENLY_SEAHORSE_MYSQL_PORT=tcp://10.98.170.14:3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP=tcp://10.98.170.14:3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_PORT=3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_ADDR=10.98.170.14
QUEENLY_SEAHORSE_MYSQL_SERVICE_PORT=3306
QUEENLY_SEAHORSE_MYSQL_SERVICE_HOST=10.98.170.14
QUEENLY_SEAHORSE_MYSQL_SERVICE_PORT_MYSQL=3306
QUEENLY_SEAHORSE_MYSQL_PORT_3306_TCP_PROTO=tcp
MYSQL_MAJOR=5.7
MYSQL_VERSION=5.7.14-1debian8

Any explanation why?

FWIW, I'm clearly exec'ing into 2 different pods. E.g.

kubectl exec "queenly-seahorse-mysql-6dc964999c-h4w54" env | grep HOSTNAME
HOSTNAME=queenly-seahorse-mysql-6dc964999c-h4w54

kubectl exec "kubernetes-bootcamp-5c69669756-5rh9t" env | grep HOSTNAME
HOSTNAME=kubernetes-bootcamp-5c69669756-5rh9t
-- Snowcrash
kubectl
kubernetes
kubernetes-pod

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2 Answers

11/11/2018

I deleted my comment and am adding this as an answer. I realized that the "QUEENLY_SEAHORSE_MYSQL_xxxx" env vars have been added by Kubernetes for a service named "queenly-seahorse-mysql" - see https://kubernetes.io/docs/concepts/services-networking/service/#environment-variables

-- apisim
Source: StackOverflow
11/11/2018

All the Kubernetes Services environment variables are shared across a namespace. This is by design so that pods can find a specific service if they need to.

There have been discussions about how to disable them, but I believe no fixes have been added upstream yet.

-- Rico
Source: StackOverflow