Develop Reference

Host ASP.NET Core in Linux with Apache Docker

I am referencing this article on Microsoft's documentation:
https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/linux-apache?view=aspnetcore-3.1
Has anyone tried to accomplish these steps in Docker container?
I have been at this for a couple of days and I can't get the kestrel-helloapp.service file to start my application automatically when I run the container.
After running the container I am able to manually go into it and start my application with dotnet WebApplication3.dll.
I am under the impression that this should happen automatically after enabling the service file.
The only way I am able to get it to work is by adding this to the Dockerfile:
ENTRYPOINT ["dotnet" ,"WebApplication3.dll"]
But when I do this it causes the Apache server to not start up automatically.
Here is my Dockerfile:
FROM centos:7
# install sudo and dotnet sdk
RUN yum install sudo -y
RUN sudo rpm -Uvh https://packages.microsoft.com/config/centos/7/packages-microsoft-prod.rpm
RUN yum install epel-release -y
RUN yum install dnf -y
RUN sudo dnf install dotnet-sdk-3.1 -y
# copy app files over
COPY ["./publish/", "/var/www/helloapp/publish/"]
# install apache and enable it
RUN sudo yum -y install httpd mod_ssl
RUN systemctl enable httpd.service
RUN yum install initscripts -y
RUN sudo service httpd configtest
# copy and enable service file
COPY ["./kestrel-helloapp.service", "/etc/systemd/system/"]
RUN sudo systemctl enable kestrel-helloapp.service
# start apache
CMD ["-D", "FOREGROUND"]
ENTRYPOINT ["/usr/sbin/httpd"]
EXPOSE 80
docker run command:
docker run -v "C:\Users\Nick\source\repos\docker-testing\version1\helloapp.conf:/etc/httpd/conf.d/helloapp.conf" -e "ASPNETCORE_URLS=http://+:8080" -p 80:80 -p 8080:8080 -t version1
helloapp.conf file:
<VirtualHost *:*>
RequestHeader set "X-Forwarded-Proto" expr="http"
</VirtualHost>
<VirtualHost *:8080>
ProxyPreserveHost On
ProxyPass / http://127.0.0.1:5000/
ProxyPassReverse / http://127.0.0.1:5000/
ServerName www.example.com
ServerAlias *.example.com
ErrorLog /var/log/httpd/helloapp-error.log
CustomLog /var/log/httpd/helloapp-access.log common
</VirtualHost>
kesterl-helloapp.service file:
[Unit]
Description=Example .NET Web MVC App running on CentOS 7
[Service]
WorkingDirectory=/var/www/helloapp/publish
ExecStart=/usr/local/bin/dotnet /var/www/helloapp/publish/WebApplication3.dll
Restart=always
# Restart service after 10 seconds if the dotnet service crashes:
RestartSec=10
KillSignal=SIGINT
SyslogIdentifier=dotnet-example
User=apache
Environment=ASPNETCORE_ENVIRONMENT=Production
[Install]
WantedBy=multi-user.target
I know the configuration is correct because everything works fine when I start the application manually. The service file just seems to be not starting the application on boot.
Any help would be greatly appreciated. Thanks!

I've run into a similar problem (just with an ubuntu base image). The problem that you are likely experiencing is related to the fact that there is one process launched from the docker container on entry point and that is not the system daemon (init, systemd, not sure which one centos is using). As a result, your services are actually not started as you described, because they would be launched on system run level change, by that exact same system daemon.
In my opinion, not launching the system daemon is a good thing as you want to minimize services running inside of your container.
On the other hand, you might actually want multiple services inside of the container. An actual solution to your problem is to write an entry point shell script and launch the services that you want to run in parallel of your main application. In my case, I wanted a customized Jenkins image, which has an entry point of /usr/local/bin/jenkins.sh. You can find this in the Dockerfile of the base image that you are using.
I've replaced the original entry point:
ENTRYPOINT ["/bin/tini", "--", "/usr/local/bin/jenkins.sh"]
with:
ENTRYPOINT ["/bin/tini", "--", "/docker-entrypoint.sh"]
Where the content of /docker-entrypoint.sh is:
#! /bin/bash
/usr/bin/cron & # This is the additional service I wanted in the background
/usr/local/bin/jenkins.sh

Docker with dotnet restore causes error: GSSAPI operation failed - An unsupported mechanism was requested

Having an ASP.NET Core 2.2 web application, I try to restore NuGet packages behind a coperate proxy
FROM mcr.microsoft.com/dotnet/core/sdk:2.2 AS sdk-image
WORKDIR /app/
ARG HTTP_PROXY
ENV HTTP_PROXY ${HTTP_PROXY}
ENV HTTPS_PROXY ${HTTP_PROXY}
COPY MyProject.csproj .
RUN dotnet restore
with the following docker-compose.yml:
version: '2'
services:
tool:
build:
context: .
args:
http_proxy: ${HTTP_PROXY}
networks:
default:
ipam:
driver: default
config:
- subnet: 192.168.239.0/21
The network got overriden because Dockers default network conflicts with internal company ranges. HTTP_PROXY is set on the host to a full url like http://user:password#proxy.internal:81.
When running docker-compose up --build it fails on restore:
Step 7/15 : RUN dotnet restore
---> Running in 62c8bb6f2f72
/usr/share/dotnet/sdk/2.2.402/NuGet.targets(123,5): error : Unable to load the service index for source https://api.nuget.org/v3/index.json. [/app/MyProject.csproj]
/usr/share/dotnet/sdk/2.2.402/NuGet.targets(123,5): error : GSSAPI operation failed with error - An unsupported mechanism was requested (Unknown error). [/app/MyProject.csproj]
ERROR: Service 'tool' failed to build: The command '/bin/sh -c dotnet restore' returned a non-zero code: 1
I could not find much information about this issue. A Github issue got this through their local TFS. But I don't have any self hosted repository, just the corporate proxy between me and NuGets server.

Seems like this is caused when the proxy requires NTLM, but the corresponding library is missing. I had this problem behind a corporate proxy and fixed it by installing the gss-ntlmssp package like this in Docker:
RUN apt-get install -y gss-ntlmssp
After installing those package, the authentication to the proxy for fetching NuGet packages works well.

Installing Matlab on a Windows Docker

Trying to install Matlab run time on a docker image along with the project I'm working on, the project is an engine that will run a variety of measurements based on what is given to it, many of these measurements use Matlab. When I run the docker though I get an error that the "MWArray assembly failed to be initialized" or that a matlab dll is missing.
I'm trying to run this in Docker for Windows due to a company requirement, and have been unable to successfully get the DockerFile to recognize the MCR. Below is the code that I've been playing with to get the MCR onto a docker.
FROM mcr.microsoft.com/dotnet/framework/runtime:4.7.2-windowsservercore-ltsc2019
ADD http://ssd.mathworks.com/supportfiles/downloads/R2017b/deployment_files/R2017b/installers/win64/MCR_R2017b_win64_installer.exe C:\\MCR_R2017b_win64_installer.zip
# Line 3: Use PowerShell
SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]
# Line 4: Unpack ZIP contents to installation folder
RUN Expand-Archive C:\\MCR_R2017b_win64_installer.zip -DestinationPath C:\\MCR_INSTALLER
# Line 5: Run the setup command for a non-interactive installation of MCR
RUN Start-Process C:\MCR_INSTALLER\bin\win64\setup.exe -ArgumentList '-mode silent', '-agreeToLicense yes' -Wait
# Line 6: Remove ZIP and installation folder after setup is complete
RUN Remove-Item -Force -Recurse C:\\MCR_INSTALLER, C:\\MCR_R2017b_win64_installer.zip
WORKDIR /app
COPY /Project/bin/Debug/*.dll ./
COPY /Project/bin/Debug/Project.exe .
ENTRYPOINT ["C:\\app\\Project.exe"]
Edit: I think I've found a working solution, following the idea from the other anwser about the ltsc2019 not working with Matlab 2017b. The below code has worked with 2017b inside a docker.
FROM mcr.microsoft.com/windows:1809

Windows Server 2019 is not supported by MATLAB R2017b, and support for it was not introduced until MATLAB R2019a.
For MATLAB R2017b you’ll need Windows Server 2016.
That’s not to say there may not be other issues as well.

Nuget Restore failure in Azure Functions on a docker container-

I am having problems with my docker build script for a basic Azure Function. I have been following this blog post:
https://medium.com/#adrianromanin/azure-functions-on-a-docker-container-7b00d2c36eb2
At the point of the nuget restore I get the following errors:
Restoring packages for
C:\src\dotnet-function-app\functionsanddockerdemo.csproj... C:\Program
Files\dotnet\sdk\2.1.403\NuGet.targets(114,5): error : Unable to load
the service index for source https://api.nuget.org/v3/index.json.
[C:\src\dotnet-function-app\functionsanddockerdemo.csproj] C:\Program
Files\dotnet\sdk\2.1.403\NuGet.targets(114,5): error : A connection
attempt failed because the connected party did not properly respond
after a period of time, or established connection failed because
connected host has failed to respond
[C:\src\dotnet-function-app\functionsanddockerdemo.csproj] The command
'cmd /S /C dotnet restore
src/dotnet-function-app/functionsanddockerdemo.csproj -s
https://api.nuget.org/v3/index.json' returned a non-zero code: 1
My docker build script:
FROM microsoft/dotnet:2.1-sdk AS installer-env
COPY . /src/dotnet-function-app
RUN mkdir "home/site/wwwroot/"
RUN dir "C:/src/dotnet-function-app"
RUN dotnet publish src/dotnet-function-app/functionsanddockerdemo.csproj --output /home/site/wwwroot
I've tried explicitly specifiying package restore via both of these commands:
RUN dotnet restore src/dotnet-function-app/functionsanddockerdemo.csproj -s https://api.nuget.org/v#3/index.json
RUN dotnet restore src/dotnet-function-app/functionsanddockerdemo.csproj --verbosity diag
However they both give the same result. I initially thought maybe my container didn't have any network connectivity, however I have connectivty confirming via:
RUN ping www.google.co.uk
My docker info:
Server Version: 18.06.1-ce
Storage Driver: windowsfilter
Windows:
Logging Driver: json-file
Plugins:
Volume: local
Network: ics l2bridge l2tunnel nat null overlay transparent
Log: awslogs etwlogs fluentd gelf json-file logentries splunk syslog
Swarm: inactive
Default Isolation: hyperv
Kernel Version: 10.0 17134 (17134.1.amd64fre.rs4_release.180410-1804)
Operating System: Windows 10 Pro Version 1803 (OS Build 17134.285)
I am sure I hav missed something basic here!

Cannot run asp.net 5 from docker

I have followed the following guide: Running ASP.NET 5 applications in Linux Containers with Docker and I cannot get this to work on my Windows PC or Linux server. My dockerfile looks like this:
FROM microsoft/aspnet
COPY . /app
WORKDIR /app
RUN ["dnu", "restore"]
EXPOSE 5000/tcp
ENTRYPOINT ["dnx", "-p", "project.json", "web"]
I then ran docker build -t myapp . and then docker run -d -p 80:5000 myapp it says it is running but I cannot open the website in the browser. I know on Windows you are supposed to find the ip address that the actual virtual machine is running against by using docker-machine ip default which ended up being 192.168.99.100 but when I navigated to http://192.168.99.100 I just get the generic "This webpage is not available" error message. I have also tried different variations of this docker run command, such as docker run -it -p 80:5000 myapp, docker run -p 80:5000 myapp, and I have also tried different ports, such as docker run -d -p 5000:5000 myapp but nothing seems to work.
I have tried this both on my windows machine and on my linux server, but they both do not work.
I am able to run dnx web without docker and everything works as expected.

Take a look at my answer here: ASP.NET 5.0 beta 8 in Docker doesn't start
Essentially, Docker is forwarding requests to your container on the 0.0.0.0 network interface, but Kestrel is only listening on localhost by default.
So yes, the requests are being passed off to your docker container, but they are not being accepted by the Kestrel webserver. For that reason, you need to override the server.urls property as others have posted:
ENTRYPOINT ["dnx", "web", "--server.urls", "http://0.0.0.0:5000"]
You should then see:
Now listening on: http://0.0.0.0:5000
when running your container. You can also do a quick docker ps command to verify that 0.0.0.0 is in fact the network interface that Docker is forwarding requests for.
I also wrote a bit about how to get ASP.NET 5 running on Docker on Windows - it's a bit more involved since not only does Docker have to forward requests to the container, but we have to get VirtualBox to pass off requests to the Docker virtual machine boot2docker (typically called default in Virtual Box) before Docker can hand them off to our container.
Post is here: http://dotnetliberty.com/index.php/2015/10/25/asp-net-5-running-in-docker-on-windows/

For a more complete understanding of your app environment, please post your project.json file and the beta version of ASP.net you are working with.
For now you can try cleaning up your Dockerfile by taking out "project.json" and "-p" arguments from the ENTRYPOINT instruction, remove tcp from the EXPOSE command, and finally, specify the "--server.urls" argument in the ENTRYPOINT instruction so that it uses 0.0.0.0 instead of the default localhost as follows:
FROM microsoft/aspnet
COPY . /project
WORKDIR /project
RUN ["dnu", "restore"]
EXPOSE 5000
ENTRYPOINT ["dnx", "web", "--server.urls"]
Alternatively, you can try dropping the EXPOSE command altogether and expose the docker port, 5000, in the ENTRYPOINT instruction as follows:
FROM microsoft/aspnet
COPY . /project
WORKDIR /project
RUN ["dnu", "restore"]
ENTRYPOINT ["dnx", "web", "--server.urls", "http://0.0.0.0:500"]
Either way you would then build your container and run it using something like the following:
$ docker run -it -p 80:5000 myapp

For anyone having this issue now in RC2, commands no longer exists. You have to update Program.cs by chaining in .UseUrls("http://0.0.0.0:5000"). You can also change from 5000 to whatever your desired port is here.
public class Program
{
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.UseUrls("http://0.0.0.0:5000")
.Build();
host.Run();
}
}

You can find a working, step-by-step tutorial for Docker and ASP.NET Core RC1 here:
https://www.sesispla.net/blog/language/en/2015/12/recipe-asp-net-5-net-core-to-the-docker-container/
The tricky part probably you are missing is to modify your projects.json command as follows:
"commands": {
"web": "Microsoft.AspNet.Server.Kestrel --server.urls http://0.0.0.0:5000"
},
By default, kestrel only accepts localhost connections... With this change you allow connection from any source.