In this post, let's have a look at how to run Azure Functions locally with Production app settings and why some explicit configuration is required compared to ASP.NET Core applications.
When developing Azure Functions, you might want to test your function app locally using Production configuration. This is a common requirement when you want to verify settings before deployment or troubleshoot production-specific issues.
This is usually how we add appsettings.*.json files to Configuration.
using Microsoft.Azure.Functions.Worker.Builder;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
FunctionsApplicationBuilder builder = FunctionsApplication.CreateBuilder(args);
builder.Configuration
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: false)
.AddJsonFile($"appsettings.{builder.Environment.EnvironmentName}.json", optional: true, reloadOnChange: false)
.AddEnvironmentVariables();
// Other configurations
IHost host = builder.Build();
host.Run();
In ASP.NET Core applications, you can simply set the ASPNETCORE_ENVIRONMENT or DOTNET_ENVIRONMENT environment variable, and the application will automatically load appsettings.<EnvironmentName>.json.
For Azure Functions, things work a bit differently.
First, Azure Functions uses AZURE_FUNCTIONS_ENVIRONMENT to determine the current environment. If not set, then it falls back to DOTNET_ENVIRONMENT.
You can set it on your launchSettings.json
{
"profiles": {
"MyProfile": {
"commandName": "Project",
"commandLineArgs": "--port 7052",
"environmentVariables": {
"AZURE_FUNCTIONS_ENVIRONMENT": "Production"
}
}
}
}Or in your local.settings.json:
{
"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
"AZURE_FUNCTIONS_ENVIRONMENT": "Production"
}
}You can also use DOTNET_ENVIRONMENT instead of AZURE_FUNCTIONS_ENVIRONMENT, both will work.
Even after setting the environment variable, you might notice that your appsettings.<EnvironmentName>.json settings are not being loaded. This is because the file is not being copied to the output directory.
Here's the important difference:
- Microsoft.NET.Sdk.Web (used by ASP.NET Core apps) automatically copies all appsettings.*.json files to the output directory.
- Microsoft.NET.Sdk (used by Azure Functions, Class Libraries, Console apps) does not.
Azure Functions projects use Microsoft.NET.Sdk by default, which means you need to explicitly configure the project file to copy your environment-specific settings files.
Something like below:
<ItemGroup>
<None Update="appsettings.Production.json">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</None>
</ItemGroup>
Hope this helps.
Happy Coding.
