Having duplicate environment variable names for a container can lead to unexpected behavior, as the last declared variable will overwrite any previous ones with the same name. This rule aims to detect and prevent such situations, thereby enhancing the clarity and predictability of Kubernetes configurations.

Why is this an issue?

If an environment variable of a container is declared multiple times with different values, it can become unclear which value will be used by the application and can lead to unpredictable behavior. Also, if an issue arises related to the environment variable, debugging can be challenging. The problem could be due to the overwritten variable, but this might take time to be noticeable.

How to fix it

Identify the duplicate environment variables for a container and remove the duplicates manually. If the same variable is needed with different values, consider using a different name for each variable.

Code examples

Noncompliant code example

apiVersion: v1
kind: Pod
metadata:
  name: env-example
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    env:
    - name: VAR1 # Noncompliant
      value: "value1"
    - name: VAR1 # Noncompliant
      value: "value2"

Compliant solution

apiVersion: v1
kind: Pod
metadata:
  name: env-example
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    env:
    - name: VAR1
      value: "value1"
    - name: VAR2
      value: "value2"

Resources

Documentation

• Kubernetes - Environment Variables for a Container