Environment variables and configuration in Azure - Step-by-Step Execution

Process Flow - Environment variables and configuration

Start Application

↓

Load Environment Variables

↓

Apply Configuration Settings

↓

Run Application with Config

↓

Use Config Values in Code

↓

End

The application starts by loading environment variables, applies configuration settings, then runs using those values.

Execution Sample

Azure

az webapp config appsettings set --name MyApp --resource-group MyGroup --settings API_KEY=12345

This command sets an environment variable named API_KEY with value 12345 for an Azure Web App.

Process Table

Step	Action	Environment Variable Loaded	Configuration Applied	Effect on Application
1	Start Application	None	None	Application starts without config
2	Load environment variables	API_KEY=12345	None	Variables ready to use
3	Apply configuration	API_KEY=12345	API_KEY=12345	App config updated
4	Run application	API_KEY=12345	API_KEY=12345	App uses API_KEY in code
5	End	API_KEY=12345	API_KEY=12345	Application runs with config

💡 Application runs using environment variables set in configuration

Status Tracker

Variable	Start	After Load	After Apply	Final
API_KEY	None	12345	12345	12345

Key Moments - 2 Insights

Why does the application not see the environment variable if it is set after the app starts?

Because environment variables are loaded at app start (see execution_table step 2). Setting variables after start requires app restart to load them.

Can environment variables be changed while the app is running?

No, changes require reloading or restarting the app to apply new environment variables (refer to variable_tracker showing values fixed after load).

Visual Quiz - 3 Questions

Look at the execution table, at which step are environment variables first available to the application?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Check the 'Environment Variable Loaded' column in execution_table rows

According to variable_tracker, what is the value of API_KEY after applying configuration?

A None

B Unset

C 12345

D Empty String

💡 Hint

Look at the 'After Apply' column for API_KEY in variable_tracker

If the environment variable API_KEY is changed after step 4 without restarting, what happens?

A Application uses new value immediately

B Application continues using old value

C Application crashes

D Application ignores environment variables

💡 Hint

Refer to key_moments about when environment variables are loaded and used

Concept Snapshot

Environment variables store config outside code.
Set them before app starts.
Azure CLI: az webapp config appsettings set.
App reads variables at start.
Changes need app restart to apply.
Use for secrets and settings.

Full Transcript

This visual execution shows how environment variables and configuration work in Azure. The app starts without config, then loads environment variables like API_KEY. These variables are applied as configuration settings. The app then runs using these values. Variables must be set before app start to be effective. Changing variables after start requires restarting the app. This ensures the app uses the correct configuration securely and reliably.

Practice

1. What is the main purpose of using environment variables in Azure web apps?

easy

A. To write application logic inside the environment

B. To separate configuration settings from the application code

C. To store large files for the application

D. To replace the need for a database

Solution

1. Step 1: Understand environment variables role

   Environment variables hold configuration data outside the code, making apps flexible and secure.

2. Step 2: Identify correct purpose in Azure context

   Azure web apps use environment variables to keep settings separate from code, allowing easy updates without code changes.

3. Final Answer:

   To separate configuration settings from the application code -> Option B

4. Quick Check:

   Environment variables separate config from code [OK]

Hint: Think: config outside code for easy updates [OK]

Common Mistakes:

• Confusing environment variables with code logic
• Using environment variables to store large files
• Assuming environment variables replace databases

2. Which Azure CLI command correctly sets an environment variable named API_KEY with value 12345 for a web app called myapp?

easy

A. az webapp config appsettings set --name myapp --resource-group mygroup --settings API_KEY=12345

B. az webapp set env --app myapp --key API_KEY --value 12345

C. az appservice env set --app myapp --name API_KEY --value 12345

D. az webapp config set --app myapp --env API_KEY=12345

Solution

1. Step 1: Recall Azure CLI syntax for setting app settings

   The correct command uses az webapp config appsettings set with --name, --resource-group, and --settings.

2. Step 2: Match command to given options

   az webapp config appsettings set --name myapp --resource-group mygroup --settings API_KEY=12345 matches the correct syntax exactly; others use incorrect commands or flags.

3. Final Answer:

   az webapp config appsettings set --name myapp --resource-group mygroup --settings API_KEY=12345 -> Option A

4. Quick Check:

   Use az webapp config appsettings set with correct flags [OK]

Hint: Remember: 'az webapp config appsettings set' sets env vars [OK]

Common Mistakes:

• Using wrong Azure CLI commands or flags
• Omitting resource group parameter
• Confusing appsettings with environment commands

3. Given this Azure web app environment variable setup:
API_URL=https://api.example.com
What will the following Python code print?

import os
print(os.getenv('API_URL'))

medium

A. os.getenv('API_URL')

B. API_URL

C. None

D. https://api.example.com

Solution

1. Step 1: Understand os.getenv behavior

   os.getenv('API_URL') fetches the value of environment variable 'API_URL' if set.

2. Step 2: Match environment variable value

   The environment variable 'API_URL' is set to 'https://api.example.com', so the print outputs this string.

3. Final Answer:

   https://api.example.com -> Option D

4. Quick Check:

   os.getenv returns env var value [OK]

Hint: os.getenv returns the variable's value, not the name [OK]

Common Mistakes:

• Expecting the variable name instead of its value
• Assuming None if variable is set
• Confusing function call with string output

4. You tried to update an environment variable in Azure CLI but the app still uses the old value. What is the most likely cause?

medium

A. Azure CLI does not support environment variable updates

B. You used the wrong variable name in the code

C. You forgot to restart the web app after updating the variable

D. Environment variables cannot be updated once set

Solution

1. Step 1: Understand environment variable update behavior

   After updating environment variables, Azure web apps often require a restart to apply changes.

2. Step 2: Identify common mistake

   Not restarting the app causes it to keep using old cached environment values.

3. Final Answer:

   You forgot to restart the web app after updating the variable -> Option C

4. Quick Check:

   Restart app to apply env var changes [OK]

Hint: Restart app after env var changes to apply them [OK]

Common Mistakes:

• Assuming variables update instantly without restart
• Confusing variable name errors with update issues
• Thinking Azure CLI cannot update variables

5. You want to securely store a database password as an environment variable in Azure App Service. Which approach is best practice?

hard

A. Use Azure Key Vault and reference the secret in the app settings

B. Store the password directly in the app settings as plain text

C. Hardcode the password inside your application code

D. Send the password as a query parameter in URLs

Solution

1. Step 1: Identify secure storage options

   Azure Key Vault is designed to securely store secrets like passwords and keys.

2. Step 2: Understand integration with app settings

   You can reference Key Vault secrets in Azure App Service app settings, avoiding plain text storage.

3. Step 3: Evaluate other options

   Storing passwords in plain text, code, or URLs exposes security risks and is not recommended.

4. Final Answer:

   Use Azure Key Vault and reference the secret in the app settings -> Option A

5. Quick Check:

   Use Key Vault for secure secret storage [OK]

Hint: Always use Key Vault for sensitive secrets [OK]

Common Mistakes:

• Storing passwords in plain text app settings
• Hardcoding secrets in code
• Exposing secrets in URLs