I have a Dockerfile which looks like this:
FROM alpine:3.9
RUN apk add --update openjdk8
RUN mkdir /var/generator/
COPY generator.jar /var/generator
EXPOSE 8080
ENTRYPOINT [ "/bin/sh" ]
Dockerfile is inside generator/ folder. I am building it using:
docker build -t generator generator/
It builds successfully:
Successfully built 878e81f622cc
Successfully tagged generator:latest
but when I am trying to run this image with
docker run -d -p 8080:8080 generator
it dies immediately. docker logs gives no output.
What is wrong with my Dockerfile? Why is the container dying?
Try to run the JAR. Currently, it just runs sh command and exits. Make it something as below to run the JAR in foreground -
FROM alpine:3.9
RUN apk add --update openjdk8
RUN mkdir /var/generator/
COPY generator.jar /var/generator
EXPOSE 8080
ENTRYPOINT ["java","-jar","/var/generator/generator.jar"]
Beside your entrypoint is wrong (sh exits immediately) I would also recommend to start with an appropriate base image instead of starting with alpine and installing the openjdk package. Since you want to run a java application just use the JRE and not a full JDK and start the application as a foreground process.
Here's a minimal version which is also more efficient in disksize as the image will be smaller.
FROM openjdk:8-jre-alpine
COPY generator.jar /opt/generator.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/opt/generator.jar"]
Related
I have a Spring boot application in a Docker container and when I run the command to execute tests I see that the app starts correctly but there is no test executed. Looks like the mvn test is completely ignored.
Below my docker commands:
docker build -t cygnetops/react-test -f Dockerfile.dev .
docker run cygnetops/react-test mvn test
Dockerfile.dev
FROM eclipse-temurin:17-jdk-alpine
VOLUME /tmp
ADD /target/demoCI-CD-0.0.1-SNAPSHOT.jar app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]
EXPOSE 5000
Entrypoints and commands are working together in a Docker container, if you specify an entrypoint, your command will be passed as an argument to the entrypoint, and if that entrypoint does nothing with the arguments passed to it, then the behaviour you are observing it totally normal.
The chapter "Understand how CMD and ENTRYPOINT interact" of the documentation provides a nice table explaining in depth how they interact.
In order to run you tests from that image, you could override the entrypoint when running you container:
docker run --entrypoint "" cygnetops/react-test mvn test
Note:
you will also have to install Maven, as it is not part of your base image
as you pointed, you will also need the POM and files of the Java project in order to run the tests, so you need to copy those sources in the image
So, add, in your Dockerfile, the lines:
COPY . .
RUN apk add --no-cache maven
If you want both to work, on the other hand, you will have to write your own entrypoint and make something from the command passed as arguments.
Here is an example:
entrypoint.sh, should be located at the same level as your Dockerfile:
#!/usr/bin/env sh
exec "$#" # execute what is passed as argument
java -Djava.security.egd=file:/dev/./urandom -jar /app.jar
Then, for your Dockerfile
FROM eclipse-temurin:17-jdk-alpine
VOLUME /tmp
RUN apk add --no-cache maven
COPY . .
COPY /target/demoCI-CD-0.0.1-SNAPSHOT.jar app.jar
COPY entrypoint.sh /usr/local/bin/
ENTRYPOINT ["entrypoint.sh"]
EXPOSE 5000
Maybe a better solution is to create a docker file that runs a script instead of plain java. for example create a runner.sh file as follow:
#!/bin/bash
CMD="java -jar app.jar"
$CMD &
SERVICE_PID=$!
mvn test
wait "$SERVICE_PID"
and this will be your dockerfile
FROM maven:3.9.0-eclipse-temurin-11-alpine
COPY . .
RUN mvn install
COPY runner.sh /scripts/runner.sh
RUN ["chmod", "+x", "/scripts/runner.sh"]
ENTRYPOINT ["/scripts/runner.sh"]
I am playing around with a docker project that builds and starts with
docker run -p 8888:8888 -v /$(pwd)/example/proto:/proto <image-name>
Inside it is a gradle based java application, about which I would like to get to know somewhat more, so I started to modify its source, adding some logs etc.
I tried to rebuild and rerun the docker image the above way but the results of my modifications don't seem to visible, the logs aren't printed etc.
I removed the image with docker rmi, but after every rebuild it seems to be the same image is being created. docker images always shows it is created 3 weeks ago and the image id is always the same
Checking on the application level the build directory contains the newly compiled java classes, so apparently on that level my changes are in effect, but it seems docker still uses the old code
Any help would be appreciated
Updated: Dockerfile
FROM gradle:7.0.0-jdk11 as cache
RUN mkdir -p /home/gradle/cache_home
RUN mkdir -p /proto
RUN touch /proto/any.proto
ENV GRADLE_USER_HOME /home/gradle/cache_home
COPY build.gradle /home/gradle/java-code/
COPY gradle.properties /home/gradle/java-code/
WORKDIR /home/gradle/java-code
RUN gradle build -i --no-daemon || return 0
FROM gradle:7.0.0-jdk11 as runner
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY . /usr/src/java-code/
WORKDIR /usr/src/java-code
EXPOSE 8888
ENTRYPOINT ["gradle", "bootRun", "-i"]
A docker build will send your local changes to your local docker deamon to be built into an image.
cd projectWithDockerfile
docker build -f ./Dockerfile -t me/gradlethingy .
docker run -p 8888:8888 -v /$(pwd)/example/proto:/proto me/gradlethingy
Without the build I'm guessing you are pulling in their <image-name> from the net each time.
I'm building a docker image out of a micronaut application.
But whenever I run the docker build command
docker build -f Dockerfile -t micronaut .
I get this error
/bin/sh: /bin/gu: No such file or directory
Here's the content of my docker file anyway:
FROM oracle/graalvm-ce:20.0.0-java11 as graalvm
RUN $GRAALVM_HOME/bin/gu install native-image
COPY . /home/app/micronautguide
WORKDIR /home/app/micronautguide
RUN $GRAALVM_HOME/bin/native-image --no-server -cp build/libs/complete-*-all.jar
FROM frolvlad/alpine-glibc
RUN apk update && apk add libstdc++
EXPOSE 8080
COPY --from=graalvm /home/app/micronautguide/micronautguide /micronautguide/micronautguide
ENTRYPOINT ["/micronautguide/micronautguide", "-Xmx68m"]
Though by running gu command from the terminal works.
Your context does not contain RUN $GRAALVM_HOME/bin/gu . What is $GRAAL_VM_HOME? Whatever this variable is, it is set as null. Also, $GRAALVM_HOME/bin/gu needs to be part of docker image.
$GRAALVM_HOME does not exists in the oracle/graalvm-ce:20.0.0-java11 container. Thus, make suer to specify the right path. In this case it is /bin/gu
I think $GRAALVM_HOME is a variable you use in the local machine and gu tool is already installed and available at /bin in the docker image. So I have kept the $GRAALVM_HOME unchanged in the second build stage.
So, the Dockerfile should be like below,
FROM oracle/graalvm-ce:20.0.0-java11 as graalvm
RUN /bin/gu install native-image
COPY . /home/app/micronautguide
WORKDIR /home/app/micronautguide
RUN /bin/native-image --no-server -cp build/libs/complete-*-all.jar
FROM frolvlad/alpine-glibc
RUN apk update && apk add libstdc++
EXPOSE 8080
COPY --from=graalvm /home/app/micronautguide/micronautguide /micronautguide/micronautguide
ENTRYPOINT ["/micronautguide/micronautguide", "-Xmx68m"]
I am new to docker,
I have pre cooked a docker image(updated and installed Java and other dependancies) and stored it on my GitHub repo,
I have stored a simple hello world Spring Boot application on an AWS S3 bucket,
I want to my DockerFile -
1. Get the docker image from my GitHub repo
2. Do an update patch
3. Set my working to directory to /home/ubuntu
4. Download application from S3 bucket using wget(it's publicly accessible)
5. run the application inside the container
After which I will run the image.
Command to build -
docker build -t someTag .
Command to run -
docker run -p 9090:8090 someTag
My java application jar that will be downloded is - docker.jar
And the application runs on port 8080
I have the following Dockerfile -
FROM someRepoHere
WORKDIR /home/ubuntu
RUN apt-get update
RUN cd /home/ubuntu
VOLUME /home/ubuntu
RUN wget S3BucketLocationHere
#RUN nohup java -jar docker.jar &
# Expose the default port
EXPOSE 8080
#Old command - CMD nohup java -jar docker.jar &
CMD ["java", "-jar", "docker.jar"]
The DockerFile is able to successfully build the image but,
My application is unreachable, It did not run inside the container.
Locally if I wget my application and run the nohup command, the application responds successfully.
Your command being run is what controls the existence of the container, when it exits/returns, the container exits and stops. Therefore you need to run your command in the foreground. When you are in an interactive shell in a container, that command is your shell. The command you've listed uses a shell, but that shell exits when it runs out of commands to process and nothing is running in the foreground:
CMD nohup java -jar docker.jar &
The string syntax will run the command with /bin/sh -c "nohup java ...".
A better option is to run with json syntax if you don't need a shell, and run your java app in the foreground, avoid the nohup and background syntax:
CMD ["java", "-jar", "docker.jar"]
A few more comments on the provided Dockerfile:
WORKDIR /home/ubuntu
RUN apt-get update
That only creates a cache inside your container that will become stale and result in cache misses if you try to use it in the future. This doesn't upgrade any packages if that's what you intended. That line should be removed.
RUN cd /home/ubuntu
This makes no filesystem changes, and will have no impact on the resulting image. The current shell state is lost after the RUN line exits, including the current directory and any variables you set. This line should be removed.
VOLUME /home/ubuntu
From this line forward, changes to /home/ubuntu will be lost. You'll only see anonymous volumes created as a result unless you specify a volume at runtime at the same location. You likely don't want the above volume line because it will break things like the next line.
RUN wget S3BucketLocationHere
This line has been obfuscated but I suspect you are outputting in /home/ubuntu because of the value of WORKDIR. Anything created here will be lost because of the VOLUME line above.
Please note: I know this questions is very similar to this one however you'll note that the solution in that case was to EXPOSE the port, which I am already doing. Hence although this questions sounds similar, I think its simply a different problem altogether with similar symptoms as the other question.
Docker Version 17.12.0-ce-mac49 (21995) here. I am experimenting with Docker for the first time and have built my first Docker image. My Dockerfile is:
FROM openjdk:8
RUN mkdir /opt/myapp
ADD build/libs/myapp.jar /opt/myapp
ADD application.yml /opt/myapp
ADD logback.groovy /opt/myapp
WORKDIR /opt/myapp
EXPOSE 9200
ENTRYPOINT java -Dspring.config=. -jar myapp.jar
I build it via:
docker build -t myapp .
Everything succeeds. I then tag it as if I'm going to push it to Quay:
docker tag <imageId> quay.io/myregistry/myapp:0.1.0-SNAPSHOT
However before I publish to Quay I want to run it locally to make sure it works:
docker run -it -p 9200:9200 -d --env-file /Users/myuser/myapp-local.env --name myapp myapp
When I run this I get an indication that the container is running, and I can even see it for a few seconds via docker ps:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f3fa8f7a4288 myapp "/bin/sh -c 'java -D…" Less than a second ago Up 7 seconds 0.0.0.0:9200->9200/tcp myapp
However after a few seconds it stops running and disappears from docker ps altogether:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
Furthermore I'm not able to SSH into the container:
docker exec -it f3fa8f7a4288 bash
Error: No such container: f3fa8f7a4288
...or see any logs/console output.
When I run myapp.jar outside of Docker (as a typical Spring Boot app, it starts up and runs beautifully without exceptions). How can I troubleshoot what is going on?
The docker logs command will show you the output a container is generating when you run it detached (with -d). This is likely to include the error message.
docker logs --tail 50 --follow --timestamps container
You can run the image in the foreground without the -d to see the output like when you run myapp.jar outside of Docker.
docker run my/image
So in this specific case:
docker run -it -p 9200:9200 --env-file /Users/myuser/myapp-local.env --name myapp myapp
If I am not mistaken, the issue you are experiencing is because you are using the shell form of ENTRYPOINT. Change it to use the exec version, as follows:
ENTRYPOINT ["java", "-Dspring.config=.", "-jar", "myapp.jar"]
The shell form will launch Java as a separate process just like a shell command. This causes PID 1 to return making Docker believe the container is finished. Using the exec form, the Java process replaces PID 1 and the container will continue running.