Compatible with .net Core 2.0 and Linux?

[dsyno]

Is metadata-extractor-dotnet compatible with .net Core 2.0 running on Linux?

I am publishing .net Core 2.0 code to AWS Lambda, which runs on Linux. If I add MetadataExtractor 2.0.0 to my Visual Studio project, the publish to AWS fails.

I publish to AWS using the AWSSDK for Visual Studio 2017. It doesn't give any details on why the publish fails. It simply says "Error uploading function" and "Upload failed."

If I uninstall MetadataExtractor, then the project publishes fine.

Any idea what's going on, and how to resolve it?

[kwhopper]

It sounds like a local issue. You might check this and see if it helps:

https://forums.aws.amazon.com/thread.jspa?messageID=826759&tstart=0

[dsyno]

I don't believe that's related, since I can publish just fine without MetadataExtractor. (And also publish just fine with several other external packages; e.g. SkiaSharp, ImageSharp, LibTiff.net).

Has anyone successfully uploaded MetadataExtractor 2.0.0 to AWS Lambda, running .net Core 2.0?

[dsyno]

I may have discovered the issue. The following are the errors that Visual Studio is complaining about, when it attempts to publish MetadataExtractor.

And it seems "there's no other option than the package owner to upgrade their references": https://stackoverflow.com/questions/47712035/

... error NU1605: Detected package downgrade: System.Diagnostics.Debug from 4.3.0 to 4.0.11. Reference the package directly from the project to select a different version. 
... error NU1605:  ProcessUpload -> Amazon.Lambda.Serialization.Json 1.2.0 -> Newtonsoft.Json 9.0.1 -> System.Xml.ReaderWriter 4.0.11 -> System.IO.FileSystem 4.0.1 -> runtime.unix.System.IO.FileSystem 4.3.0 -> System.Diagnostics.Debug (>= 4.3.0) 
... error NU1605:  ProcessUpload -> Amazon.Lambda.Serialization.Json 1.2.0 -> Newtonsoft.Json 9.0.1 -> System.Diagnostics.Debug (>= 4.0.11)
... error NU1605: Detected package downgrade: System.Diagnostics.Tracing from 4.3.0 to 4.1.0. Reference the package directly from the project to select a different version. 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Net.Primitives 4.0.11 -> runtime.unix.System.Net.Primitives 4.3.0 -> System.Diagnostics.Tracing (>= 4.3.0) 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Diagnostics.Tracing (>= 4.1.0)
... error NU1605: Detected package downgrade: System.Diagnostics.Debug from 4.3.0 to 4.0.11. Reference the package directly from the project to select a different version. 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Net.Http 4.1.0 -> System.IO.FileSystem 4.0.1 -> runtime.unix.System.IO.FileSystem 4.3.0 -> System.Diagnostics.Debug (>= 4.3.0) 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Diagnostics.Debug (>= 4.0.11)
... error NU1605: Detected package downgrade: System.Diagnostics.Tracing from 4.3.0 to 4.1.0. Reference the package directly from the project to select a different version. 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Net.Http 4.1.0 -> System.IO.FileSystem 4.0.1 -> runtime.unix.System.IO.FileSystem 4.3.0 -> System.Buffers 4.3.0 -> System.Diagnostics.Tracing (>= 4.3.0) 
... error NU1605:  ProcessUpload -> AWSSDK.S3 3.3.18.2 -> AWSSDK.Core 3.3.22.1 -> System.Net.Requests 4.0.11 -> System.Diagnostics.Tracing (>= 4.1.0)

So, is this something that MetadataExtractor has to fix?

[drewnoakes]

I've seen these errors in other situations before and IIRC got it working via assembly redirects in my consuming package. There may be better upstream solutions, as you say, but I'm not an expert.

You may find that this workaround gets things working for you:

dotnet/core#907 (comment)

If you need the library to change in some way, could you make a PR?

[dsyno]

This error occurs when 'dotnet publish' is called, so yes, you should definitely fix it. I imagine it does/will effect a lot of people.

Replicate the issue by creating a .net Core 2.0 project that includes MetadataExtractor, then try to publish that project.

"If you need the library to change in some way, could you make a PR?"
I do not understand. I assume PR=pull request, which I've never done.

Is this a problem you can fix or not?

[drewnoakes]

Yes a PR is a pull request. No better time than the present to make your first.

Is this a problem you can fix or not?

I like to think I can fix any problem given enough time and focus. Unfortunately in this case I am focussed elsewhere, which is why I asked for your help. You know more about the issue than me. It seems that updating the packages to their latest versions is not a long term solution, as your other dependencies may update which then leads back to this situation again in future. The fix should address the root of the problem, not the symptom.

[dsyno]

Well I appreciate the vote of confidence, but you're giving me too much credit. I have no idea where to even begin to fix the problem.

All I know is, include MetadataExtractor in your .net Core 2.0 project, and it will no longer publish to AWS.

So until someone is able to fix MetadataExtractor, it appears it will not work for any Amazon projects, yes?

[dsyno]

FYI, I was able to resolve this by installing Microsoft.NETCore.Targets via NuGet in Visual Studio.