Is it possible to read File from same folder where Azure function exists

Question

In my Azure C# function I need to read a .txt file. I make the .txt file in Visual studio and set it to "copy Always".

Now I am using this code to read the file

var dir = System.IO.Path.GetDirectoryName(
    System.Reflection.Assembly.GetEntryAssembly().Location);

var path = System.IO.Path.Combine(dir, "twinkle.txt");

this code doesn't work. When I open the folder which is the value of dir. It lead me to this directory ""C:\Users{username}\AppData\Local\Azure.Functions.Cli\1.0.9""

How I can store a simple txt file in Azure function. Or I need Azure Storage for this.

Anything else I can do to get this done.

Update for showing file copied

Embed that file as a resource into assembly. – tchelidze Apr 01 '18 at 11:56 — tchelidze, Apr 01 '18 at 11:56
@tchelidze I am checking that way, thanks for idea. – Anirudha Gupta Apr 01 '18 at 11:57 — Anirudha Gupta, Apr 01 '18 at 11:57
@tchelidze yes, it's working. thanks – Anirudha Gupta Apr 01 '18 at 12:03 — Anirudha Gupta, Apr 01 '18 at 12:03

score 68 · Accepted Answer · edited May 17 '23 at 19:44

68

Here is how to get to the correct folder:

public static HttpResponseMessage Run(HttpRequestMessage req, ExecutionContext context)
{
    var path = System.IO.Path.Combine(context.FunctionDirectory, "twinkle.txt");
    // ...
}

This gets you to the folder with function.json file. If you need to get to bin folder, you probably need to go 1 level up, and then append bin:

// One level up
Path.GetFullPath(Path.Combine(context.FunctionDirectory, $"..{Path.DirectorySeparatorChar}twinkle.txt"))

// Bin folder
Path.GetFullPath(Path.Combine(context.FunctionDirectory, $"..{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}twinkle.txt"))

edited May 17 '23 at 19:44

Community

1
1

answered Apr 01 '18 at 12:03

Mikhail Shilkov

34,128
3
68
107

5

I don't believe I have access to `ExecutionContext` at startup. Any other way to do that? – Bill Noel Nov 14 '19 at 17:32
1

I had the same problem @BillNoel, I've posted an answer below that address the issue. – Louie Almeda Feb 19 '20 at 14:37
You can just add `ExecutionContext context` as a parameter to the Run method of your function. – David Conlisk Nov 14 '20 at 15:30
4

`context.FunctionAppDirectory` gives you access to anything in the applications root folder `context.FunctionDirectory` only gives you access to the function specific directory – Gavin Williams Nov 21 '20 at 19:15
This will only work on Windows (if it works) – Mukus May 06 '21 at 00:13
context.FunctionAppDirectory is the right answer now. Adding this in the event somebody else lands here and gets confused. – user77232 Jul 02 '22 at 06:31

score 34 · Answer 2 · answered Feb 19 '20 at 14:35

34

For those like me who doesn't have access to ExecutionContext since we have to read a file in Startup.

var binDirectory = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
var rootDirectory = Path.GetFullPath(Path.Combine(binDirectory, ".."));

///then you can read the file as you would expect yew!
File.ReadAllText(rootDirectory + "/path/to/file.ext");

Also worth noting that Environment.CurrentDirectory might work on a local environment, but will not work when deployed to Azure.

Works inside functions too.

Reference

answered Feb 19 '20 at 14:35

Louie Almeda

5,366
30
38

2

Super useful for including Google.json files that are necessary for FirebaseAdmin functions! Thanks, louie! – Bill Noel Feb 19 '20 at 18:31
Wondering how this has worked for everyone. The executing assembly directory that I see is a temporary ASP.NET location and the config file of course does not exists there. "D:\local\Temporary ASP.NET Files\root\80e1a0b8\1c033853\assembly\dl3\dc0956b6\". – Prasad Korhale Oct 12 '20 at 22:42
Hmmm, that is strange indeed, it's maybe worth checking out the reference I included in the answer @PrasadKorhale – Louie Almeda Oct 14 '20 at 12:39
If I have the file in folder it doesn't work, it had to be directly places under root folder – lolelo Mar 22 '21 at 13:24
@PrasadKorhale, because I think you are deploying the source code (as opposed to a built assembly) and your project is being compiled on the hosting of Functions App. – Reza Mar 01 '22 at 17:33
@lolelo then you have to navigate to the folder after getting the root directory similar to what I have in the answer `rootDirectory + "/your/sub/folders/file.ext"` – Louie Almeda Mar 23 '22 at 16:59
Needed to add "wwwroot" to the end for working. var rootDirectory = Path.Combine(Path.GetFullPath(Path.Combine(binDirectory, ".."),"wwwroot")); – Ivan Valadares Jun 29 '23 at 02:07

score -1 · Answer 3 · answered Feb 20 '20 at 13:49

-1

Here is a useful link: https://github.com/Azure/azure-functions-host/wiki/Retrieving-information-about-the-currently-running-function

There is the possibility of a hard coded way:

File.ReadAllText("d:\home\site\wwwroot\NameOfYourFunction" + "/path/to/file.ext");

answered Feb 20 '20 at 13:49

Graf S.

9

4

This sound cool but hard coded code are bad. What if Azure suddenly storing Function somewhere else ? – Anirudha Gupta Feb 20 '20 at 15:01

score -1 · Answer 4 · answered Jan 30 '23 at 03:35

To use a file called pub_key.pem in an Azure Function. I'd rather do this in the .csproj file:

<ItemGroup>
    <EmbeddedResource Include="pub_key.pem">
      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
    </EmbeddedResource>
</ItemGroup>

and then read the file using a Stream

var assy = Assembly.GetAssembly(typeof(AnyClassInFunction)); 
Stream fileStream = assy.GetManifestResourceStream(typeof(AnyClassInFunction),"pub_key.pem");

Is it possible to read File from same folder where Azure function exists

4 Answers4

Linked