Kubernetes typically uses ConfigMaps and Secrets to set environment variables, which introduces additional API calls and complexity, For example, you need to separately manage the Pods of your workloads and their configurations, while ensuring orderly updates for both the configurations and the workload Pods.
Alternatively, you might be using a vendor-supplied container that requires environment variables (such as a license key or a one-time token), but you don’t want to hard-code them or mount volumes just to get the job done.

Kubernetes is an open-source container orchestration platform for automating the deployment, scaling, and management of containerized applications. With Kubernetes, developers can deploy applications across clusters of machines, ensuring high availability, scalability, and resilience. Developers can learn about Kubernetes' architecture, core concepts, and deployment strategies, and gain hands-on experience with managing containerized workloads using Kubernetes.

Kubernetes

Kubernetes v1.34 introduces a new alpha feature that allows containers to load environment variables from files generated by init containers, eliminating the need for ConfigMaps and Secrets in certain scenarios. The EnvFiles feature gate enables loading environment variables from files in emptyDir volumes using the fileKeyRef field, simplifying configuration management for vendor-supplied containers and reducing API complexity. While the feature offers a cleaner approach to environment variable management, it requires careful security considerations since sensitive data stored in emptyDir volumes could be accessible to operators with node filesystem access.

Kubernetes v1.34: Use An Init Container To Define App Environment Variables