Env var not available in scipt/command in a kind Job (Kubernetes) - bash

Question

I run this Job:
kubectl apply -f - <<EOF
apiVersion: batch/v1
kind: Job
metadata:
name: sample
spec:
template:
spec:
containers:
- command:
- /bin/bash
- -c
- |
env
echo "MY_VAR : ${MY_VAR}"
sleep 800000
env:
- name: MY_VAR
value: MY_VALUE
image: mcr.microsoft.com/azure-cli:2.0.80
imagePullPolicy: IfNotPresent
name: sample
restartPolicy: Never
backoffLimit: 4
EOF
But when I look at the log the value MY_VALUE its empty even though env prints it:
$ kubectl logs -f sample-7p6bp
...
MY_VAR=MY_VALUE
...
MY_VAR :
Why does this line contain an empty value for ${MY_VAR}:
echo "MY_VAR : ${MY_VAR}"
?
UPDATE: Tried the same with a simple pod:
kubectl -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
name: sample
spec:
containers:
- name: sample
imagePullPolicy: Always
command: ["/bin/sh", "-c", "echo BEGIN ${MY_VAR} END"]
image: radial/busyboxplus:curl
env:
- name: MY_VAR
value: MY_VALUE
EOF
Same/empty result:
$ kubectl logs -f sample
BEGIN END

Answer 1

The reason this happens is because your shell expands the variable ${MY_VAR} before it's ever sent to the kubernetes. You can disable parameter expansion inside of a heredoc by quoting the terminator:
kubectl apply -f - <<'EOF'
Adding these quotes should resolve your issue.