Aspin

A local server host for running apps as persistent background processes. Aspin itself runs as a Windows Service or a macOS launchd daemon, and lets you manage, monitor, and configure multiple apps through a web UI — without dealing with IIS.

It's designed for local development when you want services like DevMail always running in the background.

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What it is (and isn't)

Aspin is not a deployment platform or CI/CD tool. It does not run apps in a virtual environment - processes run directly on your machine. There is no authentication, and it is not meant to be exposed to the public internet.

Think of it as a lightweight alternative to IIS for local use.

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How it works

You create an app in Aspin by providing a working directory and a run command. Aspin generates a workflow file with a build step and a startup step - similar in structure to GitHub Actions workflows, but simpler and without any CI/CD automation. Builds must be triggered manually through the UI.

Example workflow (DevMail)

vars:
  output_location: ${{ aspin.apps_directory }}/DevMail
  executable_file_name: DevMail.dll

build:
  steps:
    - name: Restoring application
      working-directory: ${{ app.working_directory }}
      run: dotnet restore

    - name: Publishing application
      working-directory: ${{ app.working_directory }}
      env:
        ASPNETCORE_ENVIRONMENT: Production
        DOTNET_ENVIRONMENT: Production
      run: dotnet publish -o "${{ vars.output_location }}"

startup:
  env:
    DOTNET_SYSTEM_CONSOLE_ALLOW_ANSI_COLOR_REDIRECTION: true
    ASPNETCORE_URLS: ${{ app.urls }}
  working-directory: ${{ vars.output_location }}
  run: dotnet ${{ vars.executable_file_name }}

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Features

Monitoring

• CPU time and usage, virtual and physical memory, thread count
• OpenTelemetry metrics support - configure OTEL_EXPORTER_OTLP_ENDPOINT and OTEL_EXPORTER_OTLP_HEADERS on an app to have Aspin collect its metrics over gRPC or HTTP Protobuf

Logs

• Live app logs with ANSI color support
• Optional log file output

App management

• Custom environment variables per app
• Run-on-startup: automatically start selected apps when Aspin starts
• Retry logic with configurable retry timings

Static site server

• Built-in static file server for hosting static sites or SPA apps