Escaping '.' in helms chart yaml file - kubernetes

Question

I need to define an env var with name contains '.' characters, and Kubenetes does not seem to like it.
spec:
containers:
env:
- name: "com.my.app.dir"
value: "/myapp/subdir/"
I tried single quotes, double quotes, backslashes, double backslashes, and many other ways. Still cannot make it work. I wonder if anyone knows a way to escape the '.' characters. Thanks in advance.

Answer 1

Kubernetes doesn't have a problem setting an environment variable with a .
Here's a simple spec that logs the environment by directly running the node executable
apiVersion: v1
kind: Pod
metadata:
name: env-node
spec:
containers:
- image: 'node:12-slim'
name: env-node
command:
- node
- '-pe'
- process.env
env:
- name: OTHER
value: here
- name: 'ONE_two-Three.four'
value: 'diditwork'
And the environment output (with some kubernetes default vars removed for brevity)
{
PATH: '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin',
HOSTNAME: 'env-node',
NODE_VERSION: '12.16.1',
OTHER: 'here',
'ONE_two-Three.four': 'diditwork',
HOME: '/root'
}
Most shells (sh, bash, zsh) won't accept environment variables with a . in them. POSIX defines [a-zA-Z_][a-zA-Z0-9_]* as the allowed characters in the name of an environment variable.
So running the same node process via a shell:
spec:
containers:
- image: 'node:12-slim'
name: nodeenvtest-simple-shell
command:
- sh
- '-c'
- 'node -e "console.log(process.env)"'
env:
- name: 'ONE_two-Three.four'
value: 'diditwork'
- name: 'OTHER'
value: 'here'
Results in a missing environment variable:
{
NODE_VERSION: '12.16.1',
HOSTNAME: 'env-shell',
HOME: '/root',
OTHER: 'here',
PATH: '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin',
PWD: '/'
}
If there is no shell between the container and the app running, a . after the first character in the environment variable should be fine.