How to reference multiple external assemblies in an Azure function?

Question

Till now my Azure function was relying on only one external assembly (Assembly1), and it was working fine.

However, recently we had to do some changes due to which there are now two external assemblies where Assembly1 is referencing Assembly2.

I have deployed the Assembly2 the same was as Assembly1 (I mean, copied .dll to the "bin" folder of Azure function, and imported it in the Azure function using "#r Assembly2" statement.

This gives me following compilation error -

Exception while executing function: Functions.ProcessCsvRows. Assembly1: Could not load file or assembly 'Assembly2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified. Function started (Id=dc837832-9303-4ae4-a8ae-133ab531250c) Unable to find assembly 'Assembly2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. Are you missing a private assembly file?

Please find below the code for more details on this -

#r "Assembly1"
#r "Assembly2"

using System;
using System.Net;
using Newtonsoft.Json;
using System.IO;
using System.Collections.Generic;
using System.Configuration;
using Assembly1.Entities;

public static async Task<object> Run(HttpRequestMessage req, TraceWriter log){
    var jsonContent = await req.Content.ReadAsStringAsync();
    dynamic data = JsonConvert.DeserializeObject(jsonContent.ToString());
    ProcessCsvFileContents_Result _processResponse = await DataProcessor.ProcessCsvFileContents(data.FileContent.ToString(), connectionString, clientId, redirectUrl); // DataProcessor exists in Assembly1 only
    -- response processing code -- 
}

Much appreciated for any help on this.

yes, I already referred that, and I am performing all the steps outlined there, except the place of DLL file which I am uploading in bin folder of the relevant Azure Function, as mine is a private assembly (and not shared). As I said, this all was working fine till I had to use "Assembly1" only. Once I introduced "Assembly2", I started facing this issue. — Nirman
So you have a bin folder within your function folder that contains your dlls? That should work then as per the documentation here. Try adding ".dll" to the end of your assembly names as per doc and see if that helps. — mathewc

Fabio Cavalcante Fabio Cavalcante · Accepted Answer · 2016-11-14T17:52:02

Nirman,

Private assemblies should be referenced with their extension (e.g. .dll). Looks like you're running into an execution failure (compilation succeeds)

Can you please check the following:

Make sure both, assembly1.dll and assembly2.dll are located in the bin folder, in that function's folder
If you had updated your function reference before the file was deployed, binding could have failed. Can you please restart your Function App (restart the site)

Hope this helps!

How to reference multiple external assemblies in an Azure function?

1 Answers