Using ConfigMaps as environment variables in Kubernetes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a ConfigMap named app-config with a key APP_MODE set to production.

Kubernetes

kubectl create configmap app-config --from-literal=[1]

Drag options to blanks, or click blank then click option'

AAPP_MODE=production

BAPP_MODE production

CAPP_MODE: production

DAPP_MODE=>production

Attempts:

3 left

💡 Hint

Common Mistakes

Using spaces instead of '=' between key and value.

Using ':' or '=>' which are invalid here.

The correct syntax to create a ConfigMap from a literal key-value pair is --from-literal=KEY=VALUE.

2fill in blank

medium

Complete the Pod YAML snippet to use the ConfigMap app-config as environment variables.

Kubernetes

envFrom:
  - configMapRef:
      name: [1]

Drag options to blanks, or click blank then click option'

Aapp-config

Bappconfig

Cconfig-app

Dapp_config

Attempts:

3 left

💡 Hint

Common Mistakes

Using underscores instead of hyphens.

Changing the order of words in the name.

The ConfigMap name must exactly match the created ConfigMap, which is app-config.

3fill in blank

hard

Fix the error in this environment variable definition to correctly reference the ConfigMap key APP_MODE.

Kubernetes

- name: APP_MODE
  valueFrom:
    configMapKeyRef:
      name: app-config
      key: [1]

Drag options to blanks, or click blank then click option'

AappMode

Bapp_mode

CAppMode

DAPP_MODE

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or camelCase instead of uppercase with underscores.

Misspelling the key name.

The key name is case-sensitive and must match exactly as defined in the ConfigMap, which is APP_MODE.

4fill in blank

hard

Fill both blanks to complete the Pod spec that uses the ConfigMap app-config and sets the environment variable APP_MODE from the key APP_MODE.

Kubernetes

env:
  - name: [1]
    valueFrom:
      configMapKeyRef:
        name: [2]
        key: APP_MODE

Drag options to blanks, or click blank then click option'

AAPP_MODE

Bapp-config

Capp_mode

Dconfigmap

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect env var names that don't match the key.

Using wrong ConfigMap names.

The environment variable name should be APP_MODE and the ConfigMap name is app-config.

5fill in blank

hard

Fill all three blanks to complete the Pod spec that uses envFrom to load all keys from the ConfigMap app-config as environment variables.

Kubernetes

spec:
  containers:
  - name: myapp
    image: myapp:latest
    envFrom:
    - [1]:
        name: [2]
        optional: [3]

Drag options to blanks, or click blank then click option'

AconfigMapRef

Bapp-config

Cfalse

DsecretRef

Attempts:

3 left

💡 Hint

Common Mistakes

Using secretRef instead of configMapRef.

Setting optional to true when the ConfigMap is required.

Use configMapRef to reference the ConfigMap named app-config. The optional field is usually set to false to require the ConfigMap.

Practice

1. What is the main purpose of using a ConfigMap in Kubernetes when setting environment variables for a pod?

easy

A. To separate configuration data from application code for easier updates

B. To store container images for pods

C. To manage network policies between pods

D. To define resource limits for containers

Solution

1. Step 1: Understand ConfigMap role

   ConfigMaps hold configuration data separately from app code, allowing updates without rebuilding images.

2. Step 2: Identify correct purpose

   Among options, only separating config data matches ConfigMap's main use for environment variables.

3. Final Answer:

   To separate configuration data from application code for easier updates -> Option A

4. Quick Check:

   ConfigMap purpose = separate config data [OK]

Hint: ConfigMaps separate config from code for flexible env vars [OK]

Common Mistakes:

• Confusing ConfigMaps with container images
• Thinking ConfigMaps manage network or resources
• Using ConfigMaps to store secrets (use Secrets instead)

2. Which of the following is the correct syntax to load all keys from a ConfigMap named app-config as environment variables in a pod spec?

easy

A. envFrom:
- configMapRef:
name: app-config

B. env:
- name: app-config
valueFrom:
configMapKeyRef:
name: app-config

C. configMap:
name: app-config

D. envFrom:
- secretRef:
name: app-config

Solution

1. Step 1: Identify correct envFrom usage

   To load all keys as env vars, use envFrom with configMapRef and the ConfigMap name.

2. Step 2: Check options for syntax correctness

   envFrom: - configMapRef: name: app-config correctly uses envFrom with configMapRef. Others misuse keys or use secretRef incorrectly.

3. Final Answer:

   envFrom: - configMapRef: name: app-config -> Option A

4. Quick Check:

   Use envFrom + configMapRef for all keys [OK]

Hint: Use envFrom with configMapRef to load all keys [OK]

Common Mistakes:

• Using env instead of envFrom for all keys
• Confusing configMapRef with secretRef
• Missing indentation or wrong key names

3. Given this pod spec snippet, what environment variables will be available inside the container?

envFrom:
  - configMapRef:
      name: my-config

And the ConfigMap my-config contains keys: API_URL=https://api.example.com and TIMEOUT=30.

medium

A. Only API_URL=https://api.example.com

B. API_URL=https://api.example.com and TIMEOUT=30

C. Only TIMEOUT=30

D. No environment variables will be set

Solution

1. Step 1: Understand envFrom with configMapRef

   Using envFrom with configMapRef loads all keys from the ConfigMap as environment variables.

2. Step 2: Check ConfigMap keys

   The ConfigMap has two keys: API_URL and TIMEOUT, so both become env vars.

3. Final Answer:

   API_URL=https://api.example.com and TIMEOUT=30 -> Option B

4. Quick Check:

   envFrom loads all keys as env vars [OK]

Hint: envFrom loads all ConfigMap keys as env vars [OK]

Common Mistakes:

• Assuming only one key loads at a time
• Confusing envFrom with env and missing keys
• Thinking ConfigMap keys are not environment variables

4. You applied this pod spec to use a ConfigMap as environment variables, but the container does not see the variables. What is wrong?

envFrom:
  - configMapRef:
      name: wrong-config-name

The ConfigMap you created is named app-config.

medium

A. The pod spec must use secretRef instead of configMapRef

B. envFrom cannot be used to load ConfigMaps

C. ConfigMaps cannot be used as environment variables

D. The ConfigMap name in the pod spec does not match the actual ConfigMap name

Solution

1. Step 1: Compare ConfigMap names

   The pod spec references wrong-config-name, but the actual ConfigMap is app-config.

2. Step 2: Understand impact of name mismatch

   If names don't match, Kubernetes cannot find the ConfigMap, so env vars won't be set.

3. Final Answer:

   The ConfigMap name in the pod spec does not match the actual ConfigMap name -> Option D

4. Quick Check:

   ConfigMap name must match exactly [OK]

Hint: Check ConfigMap name spelling matches pod spec [OK]

Common Mistakes:

• Using secretRef instead of configMapRef incorrectly
• Assuming envFrom can't load ConfigMaps
• Ignoring case sensitivity in names

5. You want to update environment variables in a running pod without rebuilding the container image. Which approach using ConfigMaps is correct?

hard

A. Use a Secret instead of ConfigMap for environment variables

B. Modify the container image to include new environment variables

C. Create or update a ConfigMap and reference it with envFrom in the pod spec, then restart the pod

D. Edit the pod spec to add environment variables directly and redeploy the image

Solution

1. Step 1: Understand ConfigMap update workflow

   ConfigMaps allow updating config data separately; updating the ConfigMap and restarting the pod applies new env vars without rebuilding images.

2. Step 2: Evaluate options for best practice

   Create or update a ConfigMap and reference it with envFrom in the pod spec, then restart the pod correctly uses ConfigMap with envFrom and pod restart. Others require image rebuild or confuse Secrets with ConfigMaps.

3. Final Answer:

   Create or update a ConfigMap and reference it with envFrom in the pod spec, then restart the pod -> Option C

4. Quick Check:

   Update ConfigMap + restart pod for new env vars [OK]

Hint: Update ConfigMap and restart pod, no image rebuild needed [OK]

Common Mistakes:

• Rebuilding container image unnecessarily
• Confusing Secrets with ConfigMaps for non-sensitive data
• Editing pod spec without restarting pod