Azure Function v2 - how to load configuration as singelton?

Question

I'm migrating an Azure Function from v1 (.NET 4.7) to v2 (.NET Standard 2). In the v1 version I was using some static variables which I read from the config like this to get a singleton (of a Cosmos DB client)

private static string cosmosDbUri = ConfigurationManager.AppSettings["CosmosDb.Uri"];
//...
private static MyCosmosDbClient cosmosDbClient = new MyCosmosDbClient(cosmosDbUri, ...);

For v2 I would switch to ConfigurationBuilder for my config:

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

Now there is the problem that this needs the ExecutionContext, which I only get (or know how to get), when the function is executed.

So my question is, how to tackle this best? Build an Init(ExecutionContext context) method that I would call only if the config was not yet loaded or are there better ways to do this?

Answer 1

You can replace context.FunctionAppDirectory with Environment.CurrentDirectory.

At least, that works locally and that's exactly where you need local.settings.json to work, so this change should be safe.