# Docker Support

A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.

Using **Visual Studio Docker Tools**, Wisej.NET 3 applications can be packaged and run in these containers.

## Project

### Installing

When creating a **cross-platform** Wisej.NET 3 application, Visual Studio will prompt the user to add Docker support to the project.

<div align="left"><img src="/files/KOlUE5yqDLHuWq3egu1A" alt="Wisej.NET 3 Project Wizard"></div>

### Running

To run the Wisej.NET application in a Docker container, change the runtime target to **Docker**.

<div align="left"><img src="/files/FkodJWOgOL6aolKqDvFI" alt="Docker runtime target"></div>

{% hint style="danger" %}
When building and running a **Docker** project, the **first TargetFramework** is always used. If Docker can't run the first TargetFramework, it will target the **second** or **third** listed framework.
{% endhint %}

{% embed url="<https://docs.microsoft.com/en-us/dotnet/architecture/containerized-lifecycle/design-develop-containerized-apps/visual-studio-tools-for-docker>" %}
Visual Studio Docker Tools
{% endembed %}

## Dockerfile

Docker can build images automatically by reading the instructions from a `Dockerfile`. A `Dockerfile` is a text document that contains all the commands a user could call on the command line to assemble an image. Using `docker build` users can create an automated build that executes several command-line instructions in succession.

Below is a sample Dockerfile configured to run a **Wisej.NET 3** application that targets **.NET 5**.

<div align="left"><img src="/files/kFJuHMY6BRZQzAINf2QM" alt=""></div>

{% hint style="warning" %}
Be sure to update the Dockerfile if the **TargetFramework** is not .**NET5.0**.
{% endhint %}

{% embed url="<https://docs.docker.com/engine/reference/builder#from>" %}


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