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Deploying .Net container App to Heroku cloud

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I’m tired of searching every time I need to deploy to heroku cloud. Being that said I’m finally writing down the steps do deploy a docker container app to Heroku cloud.

By the way, Heroku Cloud it is really cool.

Requirements to deploy #

  • Docker client (windows or linux) installed Link
  • Heroku CLI (command line interface) installed Link
  • Application with a Dockerfile

Changes you have to make in your Dockerfile #

First remove the Entrypoint and EXPOSE statments of your Dockerfile.

ENTRYPOINT ["dotnet", "SOME-APP.dll"]

Instead of use the EXPOSE command we should rely on environment variable PORT (Heroku sets the output port you should use) and execute a CMD command instead of ENTRYPOINT as the last command line.

#set up as a environment variable
CMD export ASPNETCORE_URLS=http://*:$PORT

#or set up in the command line of execution
CMD ASPNETCORE_URLS=http://*:$PORT dotnet ENTRYPOINT-DLL.dll

The final Dockerfile:

FROM microsoft/dotnet:2.2-aspnetcore-runtime AS base
WORKDIR /app

FROM microsoft/dotnet:2.2-sdk AS build
WORKDIR /src
COPY . .
RUN dotnet restore "FuraFila.WebApp/FuraFila.WebApp.csproj"
WORKDIR "/src/FuraFila.WebApp"
RUN dotnet build "FuraFila.WebApp.csproj" -c Release -o /app
RUN dotnet ef database update

FROM build AS publish
RUN dotnet publish "FuraFila.WebApp.csproj" -c Release -o /app

FROM base AS final
WORKDIR /app
COPY --from=publish /app .

CMD export ASPNETCORE_URLS=http://*:$PORT
RUN echo 'we are running some # of cool things'

CMD ASPNETCORE_URLS=http://*:$PORT dotnet FuraFila.WebApp.dll

Also a sample Dockerfile can be found in my personal Github account.

Pushing thing to Heroku Container Registry #

Open your CLI (Command Line Tool), such as bash or command prompt and execute the following steps.

#first login into heroku CLI
heroku login

#build your docker image
docker build -t rick/furafila:heroku -f Dockerfile.heroku .

#test your docker image. This step it's not necessary
docker run -p 5000:5000 -d -e PORT=5000 rick/furafila:heroku

#tag your docker image
docker tag rick/furafila:heroku registry.heroku.com/rick-furafila/web

By the way, rick/furafila:heroku is the name of my application. Don’t forget to replace with yours.

#if you are not logged in into Heroku Container Registry.
heroku container:login

#pushing to Heroku cloud
docker push registry.heroku.com/rick-furafila/web

Releasing it to live #

Finally tell Heroku to release it to live environment.

heroku container:release web -a rick-furafila

Now you’re free :)

Based on articles #