连接到github / bitbucket存储库时，自动化的Spring Boot Docker Image无法在Docker Hub上构建

Question

I have a simple Dockerfile in my spring boot as follow. I am able to build the image successfully locally, and can push using my credentials.

But my build keeps failing on every attempt to build automatically.

 FROM openjdk:8-jdk-alpine LABEL maintainer="xxxxx@xxx.com" VOLUME /tmp EXPOSE 8080 ARG JAR_FILE=target/jollof.jar ADD ${JAR_FILE} jollof.jar ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","- jar","/jollof.jar"] 

From docker hub, I got this from the log.

 Building in Docker Cloud's infrastructure... Cloning into '.'... Warning: Permanently added the RSA host key for IP address 'xxx.xx.xxx.xxx' to the list of known hosts. .... .... Step 6/7 : ADD ${JAR_FILE} jollof.jar ADD failed: stat /var/lib/docker/tmp/docker- builder674045875/target/jollof.jar: no such file or directory 

Answer 1

Unlike your local environment, Docker Hub fetches then builds your project in a fresh environment, so that the file target/jollof.jar that is intended to be copied is not available in the docker context. Hence the error you observe.

So I'd suggest refactoring your Dockerfile so that mvn package or so is done in the Dockerfile itself (which is a best practice to adopt, for the sake of reproducibility). Note that this configuration will be working for Docker Hub's automated builds as well as the builds in your local environment.

For example, below is an example Dockerfile that inspired by the that of this SO answer How to convert a Spring-Boot web service into a Docker image? as well as the Dockerfile of your post:

FROM maven:3.6-jdk-8 as maven
WORKDIR /app
COPY ./pom.xml ./pom.xml
RUN mvn dependency:go-offline -B
COPY ./src ./src

# TODO: jollof-* should be replaced with the proper prefix
RUN mvn package && cp target/jollof-*.jar app.jar

# Rely on Docker's multi-stage build to get a smaller image based on JRE
FROM openjdk:8-jre-alpine
LABEL maintainer="xxxxx@xxx.com"
WORKDIR /app
COPY --from=maven /app/app.jar ./app.jar

# VOLUME /tmp  # optional
EXPOSE 8080    # also optional

ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app/app.jar"]