Azure Functions Settings

This document provides a comprehensive guide to configuring and managing settings for Azure Functions.

Configuration Sources

Azure Functions supports multiple configuration sources, allowing you to manage settings effectively across different environments.

Application Settings

Application settings are key-value pairs that are accessible by your function code. These are ideal for configuration data specific to your application, such as connection strings, API keys, or feature flags.

Settings can be managed through:

• The Azure portal.
• The Azure CLI.
• ARM templates or Bicep.
• Environment variables (for local development and containerized deployments).

Connection Strings

Connection strings are a special type of application setting used to store connection information for external services like databases or storage accounts. Azure Functions provides specific environment variables for accessing these:

• AzureWebJobsStorage: Used by the Functions runtime for managing triggers and logging.
• WEBSITE_CONTENTAZUREFILECONNECTIONSTRING: Used for remote debugging and accessing function content in Azure Files.

Managing Settings

Azure Portal

Navigate to your Azure Function App in the Azure portal. In the left-hand navigation menu, under "Settings," select "Configuration." Here you can add, edit, and delete application settings and connection strings.

Azure CLI

You can manage settings using the Azure CLI commands:

# Get all settings
az functionapp config appsettings list --name <function_app_name> --resource-group <resource_group_name>

# Add or update a setting
az functionapp config appsettings set --name <function_app_name> --resource-group <resource_group_name> --settings MySetting=MyValue

# Delete a setting
az functionapp config appsettings delete --name <function_app_name> --resource-group <resource_group_name> --setting-names MySetting

Accessing Settings in Code

Settings are injected as environment variables into your function's execution context. The method for accessing them varies slightly by language:

C#

var settingValue = Environment.GetEnvironmentVariable("MySetting");
var connectionString = Environment.GetEnvironmentVariable("MyConnectionString");

JavaScript

const settingValue = process.env.MySetting;
const connectionString = process.env.MyConnectionString;

Python

import os
setting_value = os.environ.get("MySetting")
connection_string = os.environ.get("MyConnectionString")

Special Settings

Host Settings

Some settings control the behavior of the Functions host itself. These are typically managed in the host.json file.

Example host.json snippet for controlling HTTP request timeouts:

{
  "version": "2.0",
  "http": {
    "routePrefix": "api"
  },
  "extensions": {
    "http": {
      "maxOutstandingRequests": 100,
      "batchSize": 20,
      "maxConcurrentRequests": 50
    }
  },
  "logging": {
    "logLevel": {
      "default": "Information"
    }
  }
}

Deployment Slots

When using deployment slots, settings can be marked as "sticky" to remain with a specific slot during swaps, or they can be swapped along with the code. This allows for careful management of environment-specific configurations.

Common Settings