In the past I have written an article regarding Launching your Vaadin apps in Docker and Running WAR apps in Docker with Jib. However, what if you don’t have Java installed at all on the machine (e.g. it’s a CI server) and therefore can’t run Gradle build? Or what if you don’t want to have an unfamiliar Gradle script running on your machine (e.g. could be a virus)? The solution is to perform the build itself in Docker as well, by using Docker multi-stage builds.

Building WAR images

The following example Docker file will git-clone and build the karibu10-helloworld-app example project:

# Build stage
FROM openjdk:11 AS BUILD
RUN git clone https://github.com/mvysny/karibu10-helloworld-application /app
WORKDIR app
RUN ./gradlew -Pvaadin.productionMode --info --no-daemon

# Run stage
FROM tomcat:9.0.35-jdk11-openjdk
COPY --from=BUILD /app/build/libs/app.war /usr/local/tomcat/webapps/ROOT.war

Just create an empty directory and place a single file named Dockerfile (the contents above) there, then run:

$ docker build -t test/karibu10:latest --no-cache .
$ docker run --rm -ti -p8080:8080 test/karibu10:latest

The first command will go through individual stages and build the test/karibu10 image containing Tomcat and the karibu10-helloworld-app WAR file; the second command will start the pre-built image.

Building jar images

The advantage of using jar-based apps are that the image is much smaller (since it doesn’t package Tomcat) and it starts much faster (since it embeds Jetty which starts faster than Tomcat).

The following example Docker file will git-clone and build the vaadin14-embedded-jetty-gradle example project:

# Build stage
FROM openjdk:11 AS BUILD
RUN git clone https://github.com/mvysny/vaadin14-embedded-jetty-gradle /app
WORKDIR app
RUN ./gradlew -Pvaadin.productionMode --info --no-daemon
WORKDIR /app/build/distributions
RUN unzip app.zip

# Run stage
FROM openjdk:11
COPY --from=BUILD /app/build/distributions/app /app/
WORKDIR /app/bin
EXPOSE 8080
ENTRYPOINT ./app

Just create an empty directory and place a single file named Dockerfile (the contents above) there, then run:

$ docker build -t test/vaadin14-embedded-jetty:latest --no-cache .
$ docker run --rm -ti -p8080:8080 test/vaadin14-embedded-jetty