Precompiled Azure Function Behaving Unexpectedly - azure

Question

MyLibrary.dll
public class Person
{
[JsonProperty("name")]
public string Name { get; set; }
public static async Task Save(Person person)
{
DocumentClient client = CreateDocumentClient();
await client.OpenAsync();
await client.CreateDocumentAsync(CreateDocumentCollectionUri(), person);
}
}
MyFunctionApp.dll
public class SimpleHttpTrigger
{
public static async Task Run(HttpRequestMessage req)
{
Person bob = new Person() { Name = "Bob" };
await Person.Save(bob);
}
}
MyLibrary depends on:
Newtonsoft.Json 10.0.2
Microsoft.Azure.Documents.Client 1.13.1
And MyFunctionApp depends on MyLibrary.
The issue observed in this example is that the JsonProperty attribute is ignored when SimpleHttpTrigger.Run is called by the Azure Function CLI. SimpleHttpTrigger behaves as expected when called directly from a console app.
The issue can be resolved by changing MyLibrary's dependencies to match the versions currently used by the Azure Functions CLI:
Newtonsoft.Json 9.0.1
Microsoft.Azure.Documents.Client 1.11.4
It appears that Azure Function CLI ignores libraries in MyFunctionApp/bin when it has its own version of the library (found in node_modules/azure-functions-cli/bin). In this small example it's fine to match the dependencies but it isn't feasible when MyFunctionApp has a much larger dependency.
Is my understanding of this behaviour correct?
Is there any way to specify which version of these libraries to use in precompiled functions? I believe that one could get this behaviour in scripted functions by putting the dependencies inside the function's bin folder.
Update
My assumptions about the cause of this behaviour appear to be incorrect.
The newer versions of the Newtonsoft.Json and Microsoft.Azure.Documents.Client assemblies are in fact loaded alongside the Azure Function CLI's automatically loaded assemblies.
Which makes me even more confused as SimpleHttpTrigger.Run still behaves differently when called directly from a console app than it does when called by the Azure function host.
Any ideas what's going on? Possibly something stupid on my part.
Update 2
It looks like two different versions of the Newtonsoft.Json are used, whichever way the assemblies are loaded:
MyLibrary uses Newtonsoft.Json 10.0.2 as intended, but its dependency, Microsoft.Azure.Documents.Client 1.13.1, uses Newtonsoft.Json 9.0.1
Which might explain the incompatibility of the JsonProperty attribute.
Possibly? Please help, I'm very confused!

Answer 1

Basically, you are correct about the diagnosis of the problem.
This is an open issue with Azure Functions.
I stumbled on this myself and sympathize with your frustration.
Until the issue is solved, you must use the same major version of all the dependencies you happen to share with the implementation of Azure Functions.
Here is the list of Azure Functions dependencies : https://github.com/Azure/azure-webjobs-sdk-script/blob/dev/src/WebJobs.Script/packages.config
Open issues to track:
https://github.com/Azure/azure-webjobs-sdk-script/issues/573
https://github.com/Azure/azure-webjobs-sdk-script/issues/1311