dart-scratch
All the runtime dependencies needed to add to the scratch image to run a
minimal-sized container for a Dart application.
The image includes a root certificate authority bundle for TLS (needed for making HTTPS requests).
There are examples under the examples directory if you are interested in
comparing the time until a server app is listening in a container using either
the Dart VM or the dart2native AOT compiler.
NOTE: I have only done a limited amount of testing. I'm working on a buildpack to support launching in Cloud functions/serverless environments, so feedback is appreciated if you run into any issues building or running your Dart app with
dart-scratch.
Dart AOT
If you want the fastest possible application launch and you don't require
Dart reflection (for annotation support, for example), then use
dart-scratch as shown below. This will build your app using
dart2native.
A minimal server app image will be around 25 MB and when a container is created the app will launch in sub-second time. This is well-suited for Function-as-a-Service and other types of jobs which need to execute and scale quickly.
FROM google/dart
# uncomment the following if you want to ensure latest Dart and root CA bundle
#RUN apt -y update && apt -y upgrade
WORKDIR /app
COPY pubspec.* .
RUN pub get
COPY . .
RUN pub get --offline
RUN dart2native /app/bin/server.dart -o /app/bin/server
FROM subfuzion/dart-scratch
COPY --from=0 /app/bin/server /app/bin/server
# COPY any other directories or files you may require at runtime, ex:
#COPY --from=0 /app/static/ /app/static/
EXPOSE 8080
ENTRYPOINT ["/app/bin/server"]Dart VM
If your app depends on dart:mirrors, then you can't use dart2native
(see limitations),
so use dart-scratch as shown below.
A minimal server app image will be around 50 MB and when a container is created the app can take a number of seconds before it's ready to listen on a socket. Due to the increased start time this is better suited for longer-lived app, apps that are less sensitive to job launch time, or applications that require reflection support (for annotations, for example).
FROM google/dart
# uncomment the following if you want to ensure latest Dart and root CA bundle
#RUN apt -y update && apt -y upgrade
WORKDIR /app
COPY pubspec.* .
RUN pub get
COPY . .
RUN pub get --offline
FROM subfuzion/dart-scratch
COPY --from=0 /usr/lib/dart/bin/dart /usr/lib/dart/bin/dart
COPY --from=0 /root/.pub-cache /root/.pub-cache
# Copy over the entire app...
COPY --from=0 /app /app
# ...or copy specific files and directories you require at runtime, ex:
#COPY --from=0 /app/bin/server.dart /app/bin/server.dart
#COPY --from=0 /app/lib/ /app/lib/
#COPY --from=0 /app/static/ /app/static/
EXPOSE 8080
ENTRYPOINT ["/usr/lib/dart/bin/dart", "/app/bin/server.dart"]This is not an official Google project.