Execute C# Scripts in Kestra Workflows

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Run C# code directly in your flows using dotnet-script.

Write inline .csx scripts with NuGet package references, or run arbitrary dotnet CLI commands inside a .NET SDK container.

Scripts

Use io.kestra.plugin.scripts.dotnet.Script to write C# code inline in your flow. The script is written to a temporary .csx file and executed with dotnet-script, which is installed automatically before each run. The default container image is mcr.microsoft.com/dotnet/sdk:10.0; set containerImage to override it, for example to pin an older SDK version.

id: dotnet_script
namespace: company.team


tasks:
  - id: hello_csharp
    type: io.kestra.plugin.scripts.dotnet.Script
    script: |
      Console.WriteLine("Hello from Kestra and C#");

NuGet package references

Reference NuGet packages inline with #r "nuget:PackageName,Version" directives at the top of your script. The first run with a new package triggers a NuGet restore that may take 30–60 seconds; subsequent runs use the cached result.

id: dotnet_script_nuget
namespace: company.team


tasks:
  - id: parse_json
    type: io.kestra.plugin.scripts.dotnet.Script
    script: |
      #r "nuget:Newtonsoft.Json,13.0.3"
      using Newtonsoft.Json;


      var data = new { message = "Hello from Kestra", timestamp = DateTime.UtcNow };
      Console.WriteLine(JsonConvert.SerializeObject(data));

For the full property list, see the Script plugin documentation.

Commands

Use io.kestra.plugin.scripts.dotnet.Commands when your C# code lives in namespace files or when you need direct dotnet CLI access.

dotnet-script is not pre-installed in the default image. Add it to beforeCommands when running .csx files:

id: dotnet_commands
namespace: company.team


tasks:
  - id: run_script_file
    type: io.kestra.plugin.scripts.dotnet.Commands
    namespaceFiles:
      enabled: true
    beforeCommands:
      - dotnet tool install -g dotnet-script --ignore-failed-sources || true
      - export PATH="$PATH:$HOME/.dotnet/tools"
    commands:
      - dotnet-script main.csx

Add main.csx to your namespace using the Editor or by syncing from Git. The file can contain:

Console.WriteLine("Hello from Kestra");

You can also pass a script inline using inputFiles:

id: dotnet_commands_inline
namespace: company.team


tasks:
  - id: run_inline
    type: io.kestra.plugin.scripts.dotnet.Commands
    inputFiles:
      main.csx: |
        Console.WriteLine("Hello from Kestra");
    beforeCommands:
      - dotnet tool install -g dotnet-script --ignore-failed-sources || true
      - export PATH="$PATH:$HOME/.dotnet/tools"
    commands:
      - dotnet-script main.csx

For the full property list, see the Commands plugin documentation.

Handling outputs

Variable output

Emit key-value outputs from your script using the ::{}:: pattern. Kestra captures any line matching this format and makes the values available to downstream tasks.

id: dotnet_outputs
namespace: company.team


tasks:
  - id: emit_output
    type: io.kestra.plugin.scripts.dotnet.Script
    script: |
      Console.WriteLine("::{\"outputs\":{\"test\":\"value\",\"int\":2,\"bool\":true,\"float\":3.65}}::");


  - id: use_output
    type: io.kestra.plugin.core.debug.Return
    format: "{{ outputs.emit_output.vars.test }}"

All output variables are visible in the Outputs tab of the execution.

File output

Write a file inside your script and declare it in outputFiles. Kestra captures the file into internal storage and makes it available for download or use in downstream tasks.

id: dotnet_output_file
namespace: company.team


tasks:
  - id: write_file
    type: io.kestra.plugin.scripts.dotnet.Script
    outputFiles:
      - output.txt
    script: |
      File.WriteAllText("output.txt", "Hello from C#");


  - id: log_file
    type: io.kestra.plugin.core.log.Log
    message: "{{ read(outputs.write_file.outputFiles['output.txt']) }}"

Handling metrics

Emit metrics using the same ::{}:: pattern as outputs. Kestra supports counter and timer metric types.

id: dotnet_metrics
namespace: company.team


tasks:
  - id: emit_metrics
    type: io.kestra.plugin.scripts.dotnet.Script
    script: |
      Console.WriteLine("::{\"metrics\":[{\"name\":\"recordCount\",\"type\":\"counter\",\"value\":100}]}::");
      Console.WriteLine("::{\"metrics\":[{\"name\":\"processingTime\",\"type\":\"timer\",\"value\":1.23}]}::");

Metrics appear under the Metrics tab of the execution after it completes.

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