Configure LogLevel of Azure Function using environment variables

Looking at the code (1, 2, 3) for azure functions runtime, this appears to be possible. You have to set it as

export AzureFunctionsJobHost__logging__logLevel__default=Error

This works for other host.json settings too

export AzureFunctionsJobHost__extensions__http__routePrefix=just-another-prefix

Extending the answer given by Pramod

In the portal, navigate to the Azure Function, goto the Configuration blade and press 'New application setting' :

• Name: AzureFunctionsJobHost__logging__logLevel__Default

• Value: Error

NB. Don't forget you need to press OK, then also press Save on the Configuration blade.