Overview

Application settings provide configuration values to your containerized app at runtime. App Service injects them as environment variables when the container starts. Using app settings instead of hardcoded values lets you deploy the same image across environments with environment-specific config.

Short notes (exam revision)

App settings = name/value pairs → injected as env vars
CLI: az webapp config appsettings set --settings KEY=value
All app settings are encrypted at rest; decrypted only when injected
Names: letters, numbers, underscores only
Linux + .NET nested keys: use double underscores (ConnectionStrings__DefaultConnection), not colons

Create or update app settings

Azure CLI

az webapp config appsettings set \
  --resource-group myResourceGroup \
  --name myDocumentProcessor \
  --settings \
    STORAGE_ACCOUNT_NAME=mystorageaccount \
    LOG_LEVEL=INFO \
    MAX_DOCUMENT_SIZE_MB=50

Read in Python

Python

import os

storage_account = os.environ.get("STORAGE_ACCOUNT_NAME")
log_level = os.environ.get("LOG_LEVEL", "WARNING")
max_size = int(os.environ.get("MAX_DOCUMENT_SIZE_MB", 10))

Naming rules

Allowed characters: letters, numbers, underscores
.NET nested config on Linux: ConnectionStrings:DefaultConnection → ConnectionStrings__DefaultConnection

Encryption

App Service stores settings encrypted and decrypts them only when injecting into the container. This applies to all settings, whether sensitive or not.

Use cases

Same AI document-processor image for dev/stage/prod with different storage accounts and log levels
Change MAX_DOCUMENT_SIZE_MB without rebuilding the container
Avoid baking secrets or environment names into the Dockerfile

Exam tips

App settings ≠ rebuild — same image, different env
Know double-underscore rule for .NET on Linux containers
Remember encryption-at-rest for all settings

App settings