I know you can create a project.json
file to add NuGet packages to your functions, but how can I specify what feed I want them pulled from?
Azure functions supports the standard nuget.config approach to setup custom sources. You can place a nuget.config file with your custom sources either in your function folder or in the Function App root (where it will be used for all functions)
You can find more information about the file format and specifying custom sources here: https://docs.nuget.org/consume/nuget-config-file#package-sources