Back to Blog

Overriding host.json Values in Azure Functions For Specific Environments

Have you ever ran into a situation where you’d like to modify host.json settings for only one environment? Maybe you’d like more detailed logs in your local environment or perhaps you’d like to add a custom handler. It turns out this is a possibility and I had to do some digging to find the solution. To override host.json values for a specific environment, you can add values formatted as AzureFunctionsJobHost__path__to__setting to application settings where the double underscore refers to the JSON hierarchy. For instance, if I wanted to change the default log level to “Debug”, I can reference the sample host.json file and determine that I need to set logging.logLevel.default to “Debug”. Remember that the key always starts with AzureFunctionsJobHost and we need to use underscores for the JSON hierarchy.

    "IsEncrypted": false,
    "Values": {
        "AzureWebJobsStorage": "",
        "AzureFunctionsJobHost__logging__logLevel__default": "Debug"

Now if I run my function, you’ll notice a much more detailed output:

Azure functions output after enabling debug log level

And there you have it! If you’d like more information on this, you can refer to the Microsoft docs on overriding host.json values.