I had my ups and downs with Docker. For me, it's a great tool with pros and cons but, as I mainly use Windows for my dev. environments, making it works on the Microsoft OS can be painful.
That’s why I delegate! It's easy to find a way to make a Docker container on someone else's machine. And because I love Heroku and it’s so convenient to push a container directly to your app, I picked Gitlab (that I love too) to Dockerize my app.
The Goal
- Dockerize an app and keep it on your Gitlab Registry (reusable at will)
- Use the image to deploy on Heroku
Requirements
- Git
- A Gitlab account
- An Heroku account with an empty app
- An app (as an example, I am gonna use a .Net Core 2.0 app, so .Net Core SDK)
Let’s Start
- Create a simple web API in a TestApp folder
dotnet new webapi
- Add a .gitignore file (.Net Core template here) in your TestApp folder
- Init the local repo with
git init
git add .
git commit -m “First Commit”
- Create a new repo on Gitlab and copy the address (something like git@gitlab.com:****/****.git) to add it to your local repo
git remote add origin git@gitlab.com:****/****.git
- Add a Dockerfile in your folder (change the name of the app if needed)
FROM microsoft/aspnetcore-build:2.0 AS build-env
WORKDIR /app
# Copy everything and build
COPY . ./
# You can point directly at your csproj file, specially if it's on a sub-folder
# On some .Net Core projects (MVC, usually) if you don't add --runtime linux-x64, it won't publish. See note (1)
RUN dotnet publish -c Release -o out *.csproj --runtime linux-x64
# Build runtime image
FROM microsoft/aspnetcore:2.0
WORKDIR /app
COPY --from=build-env /app/out .
# Change the name of the app here if needed (TestApp)
CMD ASPNETCORE_URLS=http://*:$PORT dotnet TestApp.dll
- Add a .dockerignore with
bin\
obj\
- Add a .gitlab-ci.yml file and change the information as required
- Commit everything and push
That’s it! Everytime you push to your repo, you will create a new Docker image and push it to Heroku.
You can pick the branch you want to deploy on the “only” part of your gitlab-ci file.
Notes
There are many issues with precompiled Views. As of today, it’s not really solved: https://www.google.fr/search?q=net+core+razor+views+precompile&oq=net+core+razor+views+precompile
