Building Custom GitHub Action with .NET Core

action.yml

name: <Name of Custom GitHub Action>
description: <Short description of Action>
inputs:
  input_parameter:
    description: <Short description of input parameter>
    required: <true|false>
    default: <default value>
runs:
  using: docker
  image: Dockerfile
  env:
    INPUT_PARAMETER: {{ inputs.input_parameter }}

dockerfile.txt

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /app

COPY *.sln .
COPY src/ ./src/

ADD entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

ENTRYPOINT ["/entrypoint.sh"]

entrypoint.sh

#!/bin/sh -l

cd /app

dotnet restore
dotnet build
dotnet run --project src/GitHubActions.Teams.ConsoleApp -- \
    --input-parameter "$INPUT_PARAMETER"

program.cs

public static class Program
{
    public static void Main(string[] args)
    {
        var card = new MessageCard()
        {
            Title = args[1],
            Summary = args[2],
            Text = args[3],
            ThemeColor = args[4],
            Sections = ParseCollection<Section>(args[5]),
            Actions = ParseCollection<BaseAction>(args[6])
        };

        var converted = JsonConvert.SerializeObject(card);

        var message = (string)null;
        var requestUri = args[0];

        using (var client = new HttpClient())
        using (var content = new StringContent(converted, Encoding.UTF8, "application/json"))
        using (var response = await client.PostAsync(requestUri, content).ConfigureAwait(false))
        {
            response.EnsureSuccessStatusCode();
        }
    }

    private static List<T> ParseCollection<T>(string value)
    {
        var parsed = string.IsNullOrWhiteSpace(value)
                     ? null
                     : JsonConvert.DeserializeObject<List<T>>(value, settings);

        return parsed;
    }
}

workflow.yaml

name: Build and Test GitHub actions
on: push

jobs:
  build_and_test:
    name: Build and test the GitHub Action
    runs-on: ubuntu-latest

    steps:
    - name: Checkout the repository
      uses: actions/checkout@v1

    - name: Run the private action
      uses: ./
      with:
        input_parameter: <Input parameter value>