Recommanded practice how to include more sophisticated configuration JSON data in Azure Function local.settings.json file?

Question

I am using Azure Functions 2

I am going through Azure Function Local settings file documentation here:

https://learn.microsoft.com/en-us/azure/azure-functions/functions-run-local#local-settings-file

Per documentation, here is an example of local.settings.json file:

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "<language worker>",
    "AzureWebJobsStorage": "<connection-string>",
    "AzureWebJobsDashboard": "<connection-string>",
    "MyBindingConnection": "<binding-connection-string>"
  },
  "Host": {
    "LocalHttpPort": 7071,
    "CORS": "*"
  },
  "ConnectionStrings": {
    "SQLConnectionString": "<sqlclient-connection-string>"
  }
}

I understand that the items in “Values” will be available through environment variables like Environment.GetEnvironmentVariable

I need to include more sophisticated settings ( nested JSON data with arrays in them) in my Function’s settings.

What would be the best practice or recommended practice to do that?

Answer 1

Values collection is expected to be a Dictionary<string, string>, therefore we can't put nested JSON data with arrays inside. Try to create a new section for your Json data and read Json file as usual. We can't use Environment.GetEnvironmentVariable because the custom settings are not imported into environment variables.

{
  "Values": {},
  "CustomSettings":{}
}

Add ExecutionContext context to function method signature to locate settings file.

var reader = new StreamReader(context.FunctionAppDirectory+"/local.settings.json");
var myJson = reader.ReadToEnd();

For v2 function, we can use ConfigurationBuilder.

var config = new ConfigurationBuilder()
    .SetBasePath(context.FunctionAppDirectory)
    .AddJsonFile("local.settings.json", optional: false, reloadOnChange: true)
    .AddEnvironmentVariables()
    .Build();

local.settings.json is designed to provide local dev with an equivalent of Application settings in Azure portal, it's not published to Azure by default. To publish it, right click on project> Edit <functionappname>.csproj and remove <CopyToPublishDirectory>Never</CopyToPublishDirectory>.