Develop Reference

Cannot start lambda with Mock Lambda Test Tool

I've been working with AWS lambdas for a few months. I was working with a lambda and it was fine at the end of the day. I came back to work on it the next day, and I can't get Visual Studio to even start the application using the Mock Lambda Test Tool.
I ended up creating an empty lambda that just returns the input (the standard project code that AWS gives you as a template) and that won't even run. I hit the play button to star the Mock Lambda Test Tool, it looks like it will run for a couple seconds, then it closes down. The command window does not even pop up.
This is the code from the template project.
public string FunctionHandler(string input, ILambdaContext context)
{
return input?.ToUpper();
}
This is all I get in the output window of VS:
The target process exited without raising a CoreCLR started event.
Ensure that the target process is configured to use .NET Core. This
may be expected if the target process did not run on .NET Core. The
program '[16700] dotnet-lambda-test-tool-2.1.exe: Program Trace' has
exited with code 0 (0x0). The program '[16700]
dotnet-lambda-test-tool-2.1.exe' has exited with code -2147450726
(0x8000809a).
I have tried re-installing the AWS toolkit, and also tried re-installing Visual Studio. This is an issue with VS 2017 and VS 2019. I just installed 2019 to see if that would fix the issue. Any help would be appreciated.

I came to this question having the very same issue. After installing AWS Toolkit I found that the lambda test tool was not installed and therefore I got the same error just as the OP. The only difference is that I was targeting .Net Core 3.1 and therefore I needed amazon.lambda.testool-3.1. However this answer should work for both scenarios.
Unfortunately I did not have the same luck as the OP of having a nice co-worker that could give me the files I needed. So, if this is also your case please continue reading.
In the official project site, which can be found here, there are the instructions to install the tools. It also says that installing the latest version of AWS Toolkit should be enough to have the tools installed (it was not in my case and probably in yours).
It says that in order to install the tools you should run the following commands:
dotnet tool install -g Amazon.Lambda.TestTool-3.1
or
dotnet tool install -g Amazon.Lambda.TestTool-2.1
depending on which tool you need.
However, running these commands fails with the following message:
The tool package could not be restored.
Tool 'amazon.lambda.testtool-2.1' failed to install. This failure may have been caused by:
* You are attempting to install a preview release and did not use the --version option to specify the version.
* A package by this name was found, but it was not a .NET Core tool.
* The required NuGet feed cannot be accessed, perhaps because of an Internet connection problem.
* You mistyped the name of the tool.
For more reasons, including package naming enforcement, visit https://aka.ms/failure-installing-tool
And since the project is still in preview I just had to find the latest stable version in order to specify it in the command. For .net core 3.1 here is the nuget site, there I found version 0.10 to be the latest, so the command should look like:
dotnet tool install -g --version 0.10 Amazon.Lambda.TestTool-3.1

I have faced the same issue and when i tried to install dotnet-lambda-test-tool-3.1.exe using command prompt I got this issue:
Failed to create shell shim for tool 'amazon.lambda.testtool-3.1': Command 'dotnet-lambda-test-tool-3.1' conflicts with an existing command from another tool.
Tool 'amazon.lambda.testtool-3.1' failed to install.
And I did the following to fix issue
Deleted the dotnet-lamda-test-tool-3.1.exe from the installed folder (C:\Users%USERNAME%.dotnet\tools\dotnet-lambda-test-tool-3.1.exe)
Run dotnet tool install -g --version 0.10 Amazon.Lambda.TestTool-3.1 on cmd.

I have faced the same issue and got errors like "dotnet-lamda-test-tool-2.1.exe has exited with code.."
I did the following to fix the issue
Removed the dotnet-lamda-test-tool-2.1.exe from the installed folder
(C:\Users%USERNAME%.dotnet\tools\dotnet-lambda-test-tool-2.1.exe)
Removed the [amazon.lambda.testtool-2.1] folder as well
(C:\Users%USERNAME%.dotnet\tools\tools.store\amazon.lambda.testtool-2.1)
Installed dotnet tool from Developer command prompt using the command
[install -g Amazon.Lambda.TestTool-2.1]
Run the project. It is working

I have seen this issue many time on my system with dotnet-lambda-test-tool-6.0. Only one fix work for me
Remove dotnet-lambda-test-tool-6.0.exe from C:\Users\username.dotnet\tools
Open Command prompt from C:\Users\username.dotnet\tools
run command dotnet tool install -g Amazon.Lambda.TestTool-6.0

For anyone else that hits this same issue, it had to do with the the AWS toolkit install. I did not modify it, but somehow it was no longer working. I tried un-installing and re-installing, but it was still having issues running it. A co-worker sent me the exe and subdirectory that was setup on his machine under C:\Users\%user%.dotnet\tools. The exe is located in this directory, and there is another folder under .store for amazon.lambda.testtool-2.1. That directory had different folders and files than what I was able to install. So I copied in what he had and it worked. There might be a profile file associated to the tools install that points to these folders and files that might need to be modified. Since I was able to fix it with this, I didnt look any further into that.

I had the same issue with my .NET 6.0 lambda project. I installed the tool by executing dotnet tool install --global Amazon.Lambda.TestTool-6.0 --version 0.12.6 as suggested on https://www.nuget.org/packages/Amazon.Lambda.TestTool-6.0
Just ensure it is installed at %USERPROFILE%\.dotnet\tools\dotnet-lambda-test-tool-6.0.exe

I got the same issue with VS2019 with lambda design in 3.1 version and in Output window getting error
The target process exited without raising a CoreCLR started event. Ensure that the target process is configured to use .NET Core. This may be expected if the target process did not run on .NET Core.
Then checked the folder having multiple version of lambda-test-tool in path
C:\Users{username}.dotnet\tools
I removed all the lambda-test-tool and installed the required tool only with version 3.1 by command in developer command prompt:
dotnet tool install -g --version 0.10 Amazon.Lambda.TestTool-3.1
Then I can able to debug the lambda

How can I install and run MDbg on macOS from the dotnet command line?

I'm trying to install and run the Managed debugger (MDbg) from dotnet core.
https://www.nuget.org/packages/MDbg/0.1.0
says I can run dotnet add package MDbg --version 0.1.0.
This adds a dependency to a CS project but does not give me access to an MDbg executable.
What do I need to do to access a command line debugger for C#?
I don't want to use VSCode or Visual Studio to access a debugger, I want to debug from the command line.

MDbg can only be used to debug full .NET Framework applications (and only on windows). There is an open issue to port it to .NET Core, but as of now it's not done yet. Here is documentation link describing different available options to debug .NET Core applications (including on OSX).

Can Visual Studio Code work with mixed-language, .NET Core solutions?

Is there a simple fix for the following? Or is this a bug in VSCode and/or the language-specific extensions?
I created two projects and a solution like this:
dotnet new library -lang F# -o .\ClassLibrary
dotnet new console -lang C# -o .\MainProgram
dotnet new sln
dotnet sln add .\ClassLibrary\ClassLibrary.fsproj
dotnet sln add .\MainProgram\MainProgram.csproj
I added a project reference to the ClassLibrary from within the MainProgram.
dotnet add reference ..\ClassLibrary\ClassLibrary.fsproj
I updated the Program.cs to call the ClassLibrary.
static void Main(string[] args)
{
ClassLibrary.Say.hello("world.");
}
I can restore, build, and run the program successfully.
dotnet restore
dotnet run -p .\MainProgram\MainProgram.csproj
The problem is when I open the solution folder in Visual Studio Code.
When I open Program.cs, the editor red-underlines the F# library types as being missing.
When I open Library.fs, the editor red-underlines pretty much everything. Interestingly, the errors are from a C# compiler, not an F# compiler.
Ctrl-Shift-B builds the projects with 0 Warning(s) and 0 Error(s).
VSCode's Problems windows displays 12 compiler errors.
I have also tried opening the project folders separately.
If I open VS Code in the F# library project, Intellisense works.
If I open VS Code in the C# console project, the editor still does not recognize the types from F# library.
Update
I have VS Code version 1.15.1, with five extensions installed.
C#, 1.12.1
Ionide-fsharp, 2.33.0
Language PL/SQL, 1.0.4
Mono Debug, 0.15.7
XML Tools, 1.9.2

Looks like we just need to wait for this fix.
And, if you have Visual Studio Build Tools 2017 installed, update to the latest version and F# compiler workload.

How to compile mono projects from command line on mac

I'm required to compile a C# project from the command line (not from within the IDE). It works just fine under linux (to be exact under Fedora and Ubuntu). I just install the mono-xbuild package and the build script is capable of executing the xbuild command. The problem is that there's no xbuild or mdtool inside the home-brew repositories and installing xamarin studio while building isn't the solution because it places the binary in different places depending on a whole range of conditions.
How do I get my build/install script to work out of the box under MacOSX?

You need to install .NET for macOS, then use a dotnet command to run compile and execute a .NET project.
Here are the commands to run a Hello World's app:
dotnet new console -o myApp
cd myApp
dotnet run
For Mono apps, you need to install Mono framework (available as a Mac .pkg file)
Consider also installing MSBuild (The Microsoft Build Engine). It requires OpenSSL (install via: brew install openssl). See: Building Testing and Debugging on .Net Core MSBuild.

Building a .NET Core app via command line, so that it works on a machine without .NET Core installed

My end goal is to create a cross-platform (non-web) console application, so I'm exploring .NET Core right now.
In my previous .NET projects, I did all the development inside Visual Studio, but I also created a batch/MSBuild file so I could build the whole project (including setups, NuGet packages, zip files with binaries etc.) with one single click. Here's an example from a previous project.
In the end, I want to do something similar with my .NET Core test project.
But right now I'm failing at the first step: I'm unable to build it outside Visual Studio, so that the result works on another Windows machine without .NET Core installed.
(in the first step, I'm ignoring the cross-platform part - I'll be happy to get it to work on Windows)
What I have
I managed to get it to work inside Visual Studio 2015 Community Edition as follows:
create new project in Visual Studio: "New Project" ⇒ "Web" ⇒ "Console Application (Package)"
create new publish profile inside Visual Studio ("Build" ⇒ "Publish" in the menu).
This will create a PowerShell script (and an XML file with settings)
Here's my test project on GitHub.
When I do "Build" ⇒ "Publish" in the menu again, Visual Studio apparently executes the previously created PowerShell script again.
The result is slightly over 90 MB, consists of 825 files in 598 folders, and looks like this:
When I copy it on another machine (Win 7 / .NET 4 installed / .NET Core not installed), it works.
What I tried to get the same result outside Visual Studio
1. dotnet publish
This answer and this answer sound like I can use dnu publish to achieve the same result via the command line.
I understand that parts of .NET Core are still moving targets right now, so apparently dnu is now dotnet instead.
So I tried to execute dotnet publish (and created a batch file) for it:
dotnet publish "%~dp0\src\CoreTestVisualStudio" -c Release -r win7-x64 -o "%~dp0\release\cli"
The result consists of an .exe file and a bunch of DLLs, only 25 files and 1.5 MB, all in one single folder:
Obviously the .NET Core runtime is missing here, and as expected, this app crashes when I try to execute it on a machine without .NET Core installed (the same one as mentioned above).
2. The PowerShell script from the publish profile
I tried to execute the PowerShell script (which was created when I created the publish profile) outside Visual Studio, but it failed because the script expects some parameters and I don't know what to pass:
param($publishProperties, $packOutput, $nugetUrl)
There's also this line in the script:
# to learn more about this file visit http://go.microsoft.com/fwlink/?LinkId=524327
...but the link just points to the landing page of the .NET Web Development and Tools Blog.
TL;DR
What am I doing wrong?
I know that the first release of .NET Core mainly focuses on ASP.NET, but as I understood it, ASP.NET Core apps are just console apps as well, so I thought a basic console app would work now.
On the other hand, most of the console app "getting started" docs are still missing, so maybe it's just too early and dotnet publish for console apps is not finished yet?
Edit after a few days: I'm suspecting that I'm doing nothing wrong and that it's an issue in the.NET Core command line tools, so I posted it to the command line tools' issue tracker.

Problem solved!
I posted it on the issue tracker of the .NET Core command line tools, and it turned out that it was a bug in dotnet publish - it didn't bundle the C++ runtime, which is needed to execute the compiled app on a machine without .NET Core installed.
The temporary solution was to install the C++ runtime.
The "real" solution was made in a pull request three days ago, which is included in the latest installer now.
With this version, dotnet publish does bundle the C++ runtime, so the result will work on a machine without .NET Core.

For dnu:
There's an option for dnu publish called --runtime that specifies the runtime to include when publishing. You would use the full runtime name with the command, e.g.:
dnu publish --runtime dnx-clr-win-x86.1.0.0-rc1
For dotnet:
You don't need to specify the runtime or framework versions -- by default, dotnet publish will use the framework from project.json and the current runtime flavor. However, the documentation states that:
dotnet-publish command also requires certain dependencies in the project.json to work. Namely the Microsoft.NETCore.Runtime package must be referenced as a dependency in order for the command to copy the runtime files as well as the application's files to the published location.