100-Days-Of-DevOps-Challenge-KodeKloud

Print Environment Variables

The Nautilus DevOps team is working on to setup some pre-requisites for an application that will send the greetings to different users. There is a sample deployment, that needs to be tested. Below is a scenario which needs to be configured on Kubernetes cluster. Please find below more details about it.

• Create a pod named print-envars-greeting.

• Configure spec as, the container name should be print-env-container and use bash image.

• Create three environment variables:

  • GREETING and its value should be Welcome to

  • COMPANY and its value should be xFusionCorp

  • GROUP and its value should be Group

• Use command [“/bin/sh”, “-c”, ‘echo “$(GREETING) $(COMPANY) $(GROUP)”’] (please use this exact command), also set its restartPolicy policy to Never to avoid crash loop back.

• You can check the output using kubectl logs -f print-envars-greeting command.

Note: The kubectl utility on jump_host has been configured to work with the kubernetes cluster.

Steps

1. Create a k3s-pod.yml using this YAML file

2. Let’s run the following command to create the pod:

    kubectl apply -f k3s-pod.yml
   

3. Verify results

    kubectl logs -f print-env-greeting
   

   It should print the environment variables as per command we have used in the container

Good to Know?

Environment Variables

• Configuration: Pass configuration to containers
• Secrets: Store sensitive information securely
• Service Discovery: Kubernetes injects service information
• Runtime Configuration: Modify behavior without rebuilding images

Variable Sources

• Direct Values: Hardcoded values in pod spec
• ConfigMaps: Non-sensitive configuration data
• Secrets: Sensitive data like passwords and keys
• Field References: Pod/container metadata
• Resource References: CPU/memory limits and requests

Best Practices

• Externalize Config: Keep configuration outside images
• Use ConfigMaps: For non-sensitive configuration
• Use Secrets: For passwords, tokens, certificates
• Validation: Validate environment variables in application

Pod Lifecycle

• Init Containers: Run before main containers
• Restart Policy: Never, Always, OnFailure
• Completion: Pod completes when all containers exit
• Job Pattern: Use for batch processing tasks

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