Issue
I am trying to set up a Docker container that builds and runs a small application. This is my Dockerfile:
#####################
# build the jar
#####################
FROM gradle:jdk11 as builder
COPY --chown=gradle:gradle application /application
WORKDIR /application
RUN gradle build
#####################
# run the app
#####################
# Use this on a non-arm machine
# FROM openjdk:11
# Use this on an arm machine, such as a raspberry pi
FROM arm32v7/adoptopenjdk:11
EXPOSE 8080
COPY --from=builder /application/build/libs/myjar.jar .
WORKDIR /
CMD java -jar ./myjar.jar
docker build -t myimage . works without problems on my personal machine (a Macbook Pro). If I try to build the image on a Raspberry Pi 4B (which is ultimately the goal), it hangs at the RUN gradle build step and never completes.
This is my terminal output:
pi@raspberrypi:~/development/my_test $ docker build -t test .
Sending build context to Docker daemon 15.92MB
Step 1/9 : FROM gradle:jdk11 as builder
---> 0924090a3770
Step 2/9 : COPY --chown=gradle:gradle application /application
---> Using cache
---> b702fc76b9cb
Step 3/9 : WORKDIR /application
---> Using cache
---> dbc2aac75c7c
Step 4/9 : RUN gradle --no-daemon build
---> Running in faec45c6cf01
OpenJDK Server VM warning: No monotonic clock was available - timed services may be adversely affected if the time-of-day clock changes
And that's it. Nothing further happens.
At first, I had ignored the OpenJDK warning since I had seen it with other images and had no problems running them. After every other option failed, I started to suspect it might be the culprit. How can this be resolved?
Solution
I found the solution: As it turns out, the missing monotonic clock can lead to unpredictable behaviour with java. Some applications run, some have errors, some don't start. Turns out, the missing clock issue can be fixed by installing libseccomp 2.4.2 or higher, which unfortunately does not get served by apt on the pi. So it seems like the only way currently is a manual install as described here, from the source page here. I did this and the error went away, Gradle started to run, build my app and print the proper output to the terminal.
Answered By - michpohl