Create a Linux-based Docker file for .NET Framework project

Question

I have an ASP.Net Framework 4.8 project. I want to create a Linux-based Docker file for this project, but I can't find a Linux-based image to use as a base image in my Docker file for .NET Framework. How can I create a Docker file for this?

Answer 1

Finally, after a week of trying, I was able to get an answer.

We have to base the image on Nginx and install the mono on it.

1. Create a folder that contains the following:

2. Publish your asp project in the dist folder.
3. In the Nginx folder create a folder with the sites-available name.
4. In the sites-available folder create a file with the default name and the following codes:

    server {
             listen   80;
             access_log   /var/log/nginx/mono-fastcgi.log;
             root /var/www/;
             server_tokens off;
             more_clear_headers Server X-AspNet-Version;
    
             location / {
                     index index.html index.htm default.aspx Default.aspx;
                     fastcgi_index /;
                     fastcgi_pass unix:/var/run/mono-fastcgi.sock;
                     include /etc/nginx/fastcgi_params;
             }
     }

5. In the Nginx folder create a file with the fastcgi_params name and the following codes:

fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;

fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  REQUEST_SCHEME     $scheme;
fastcgi_param  HTTPS              $https if_not_empty;

fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;

fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;

fastcgi_param  PATH_INFO          "";
fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;

6. In the pools folder create a file with the sample.webapp name and the following codes:

<?xml version="1.0" encoding="UTF-8"?>
<apps>
    <web-application>
        <name>root</name>
        <vhost>*</vhost>
        <vport>-1</vport>
        <vpath>/</vpath>
        <path>/var/www/sample-app/</path>
    </web-application>
</apps>

7. supervisord.conf file:

[supervisord]
logfile=/var/log/supervisor/supervisord.log
logfile_maxbytes = 50MB
nodaemon=true
user=root

[program:mono]
command=fastcgi-mono-server4 --appconfigdir=/etc/mono/pools --socket=unix --filename=/var/run/mono-fastcgi.sock --printlog --name=mono
user=root
stdout_logfile=/dev/stdout
stdout_logfile_maxbytes=0
stderr_logfile=/dev/stderr
stderr_logfile_maxbytes=0

[program:nginx]
command=nginx
user=root
stdout_logfile=/dev/stdout
stdout_logfile_maxbytes=0
stderr_logfile=/dev/stderr
stderr_logfile_maxbytes=0

8. Finally Dickerfile:

FROM mono:latest

RUN apt-get update \
  && apt-get install -y \
  iproute2 supervisor ca-certificates-mono fsharp mono-vbnc nuget \
  referenceassemblies-pcl mono-fastcgi-server4 nginx nginx-extras \
  && rm -rf /var/lib/apt/lists/* /tmp/* \
  && echo "daemon off;" | cat - /etc/nginx/nginx.conf > temp && mv temp /etc/nginx/nginx.conf \
  && sed -i -e 's/www-data/root/g' /etc/nginx/nginx.conf

COPY nginx/ /etc/nginx/
COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
COPY pools /etc/mono/pools
COPY dist /var/www/sample-app


EXPOSE 80

ENTRYPOINT [ "/usr/bin/supervisord", "-c", "/etc/supervisor/conf.d/supervisord.conf" ]

Answer 2

.NET Framework is not cross-platform. Neither is ASP.NET itself. They do not work on Linux. So there are no Linux-based container images that would let you run .NET Framework or ASP.NET Framework.

And you can not make a custom one; .NET Framework will simply not run on Linux.

That's why Microsoft created .NET Core (and now just called .NET) and ASP.NET Core, so they would be cross-platform and you could use those on Linux, including Linux-based container images.

---

As suggested in some comments, you might be able to use mono. Mono is a (not really supported) implementation of .NET Framework that aims to work on Linux. It's not 100% bug for bug compatible with .NET Framework, so your application may or may not work with it.

---

A better, but more difficult option, would be to port your application to ASP.NET Core 6, which is supported on Linux-based containers.