As I play with .NET core, I was getting a little frustrated with waiting
for docker build and docker push to complete - the docker images for
.net core are pretty large - weighing in at a gig as shown below. My
trivial web service is hardly 80mb with dependencies - so this did not
feel good at all.
rraghur/webapi-app v3 9ff77929c379 25 hours ago 976.5 MBThe .net project template sets up a Dockerfile - and while this is
great, it’s geared more towards development rather than production. It
goes something like this:
FROM microsoft/dotnet:latest
COPY . /app
WORKDIR /app
RUN ["dotnet", "restore"]
RUN ["dotnet", "build"]
EXPOSE 5000/tcp
CMD ["dotnet", "run", "--server.urls", "http://*:5000"]Here’s the trouble - it basically needs the sdk and builds and runs the
app inside the container. Also problematic is that the source is pushed
inside the container. What if we just push binaries and use only the
runtime?
First, make the app self-contained (SCD). In project.json, you need to
remove the platform dependency type (since the platform’s going to be
packaged with the app). Then also add ubuntu.14.04-x64 under
runtimes -
"runtimes": {
"win81-x64": {},
"ubuntu.14.04-x64": {},
"debian.8-x64": {}
},Second, let’s publish - dotnet publish -r ubuntu.14.04-x64. This will
generate the app with all dependencies in
bin/debug/netcoreapp1.1/ubuntu-14.04-x64/publish
Finally, let’s update the docker file to package this in:
FROM microsoft/dotnet:1.1-runtime-deps
COPY ./bin/Debug/netcoreapp1.1/ubuntu.14.04-x64/publish /app
WORKDIR /app
EXPOSE 5000/tcp
CMD ["./WebAPIApplication", "--server.urls", "http://*:5000"]With the above, a docker build results in a much more svelte 230MB image - that’s a 76% reduction in fat :)!
rraghur/webapi-app v5 815cbcecaea9 19 seconds ago 230.8 MBLet’s take it out for a spin:
D:\WebAPIApplication>docker run -it --rm rraghur/webapi-app:v5
Hosting environment: Production
Content root path: /app
Now listening on: http://*:5000
Application started. Press Ctrl+C to shut down.Keep shipping!
