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This Dockerfile hangs after the download has completed:

FROM ubuntu:18.04
MAINTAINER Dean Schulze

ENV JS_CE_VERSION 7.1.0
ENV JS_CE_HOME /opt/jasperreports-server-cp-${JS_CE_VERSION}
ENV PATH $PATH:${JS_CE_HOME}

RUN apt-get update && apt-get install -y wget \
&& wget --progress=bar:force:noscroll -O TIB_js-jrs-cp_${JS_CE_VERSION}_linux_x86_64.run https://sourceforge.net/projects/jasperserver/files/JasperServer/JasperReports%20Server%20Community%20Edition%20${JS_CE_VERSION}/TIB_js-jrs-cp_${JS_CE_VERSION}_linux_x86_64.run \
&& chmod a+x TIB_js-jrs-cp_${JS_CE_VERSION}_linux_x86_64.run \
&& /TIB_js-jrs-cp_${JS_CE_VERSION}_linux_x86_64.run --mode unattended --jasperLicenseAccepted yes --postgres_password Postgres1 --prefix ${JS_CE_HOME} \
&& rm TIB_js-jrs-cp_${JS_CE_VERSION}_linux_x86_64.run \
&& rm -rf ${JS_CE_HOME}/apache-ant ${JS_CE_HOME}/buildomatic \
${JS_CE_HOME}/docs ${JS_CE_HOME}/samples ${JS_CE_HOME}/scripts \
&& apt-get clean

EXPOSE 8080

CMD ctlscript.sh start && tail -f /dev/null

The last few lines of output are

Resolving superb-dca2.dl.sourceforge.net (superb-dca2.dl.sourceforge.net)... 209.61.193.20
Connecting to superb-dca2.dl.sourceforge.net (superb-dca2.dl.sourceforge.net)|209.61.193.20|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 343517555 (328M) [application/x-makeself]
Saving to: 'TIB_js-jrs-cp_7.1.0_linux_x86_64.run'

TIB_js-jrs-cp_7.1.0 100%[===================>] 327.60M  1.60MB/s    in 3m 52s  

2018-07-28 03:15:28 (1.41 MB/s) - 'TIB_js-jrs-cp_7.1.0_linux_x86_64.run' saved [343517555/343517555]

How do I diagnose a docker build that hangs like this?

Edit

Here's the requested output:

$ docker image history d5d47e51eafc
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
d5d47e51eafc        23 minutes ago      /bin/sh -c #(nop)  ENV PATH=/usr/local/sbin:…   0B                  
831a3a551fa7        23 minutes ago      /bin/sh -c #(nop)  ENV JS_CE_HOME=/opt/jaspe…   0B                  
e8361426e492        23 minutes ago      /bin/sh -c #(nop)  ENV JS_CE_VERSION=6.3.0      0B                  
7af364f52b1b        23 minutes ago      /bin/sh -c #(nop)  MAINTAINER JS Minet          0B                  
735f80812f90        30 hours ago        /bin/sh -c #(nop)  CMD ["/bin/bash"]            0B                  
<missing>           30 hours ago        /bin/sh -c mkdir -p /run/systemd && echo 'do…   7B                  
<missing>           30 hours ago        /bin/sh -c sed -i 's/^#\s*\(deb.*universe\)$…   2.76kB              
<missing>           30 hours ago        /bin/sh -c rm -rf /var/lib/apt/lists/*          0B                  
<missing>           30 hours ago        /bin/sh -c set -xe   && echo '#!/bin/sh' > /…   745B                
<missing>           30 hours ago        /bin/sh -c #(nop) ADD file:4bb62bb0587406855…   83.5MB

It looks like the lines are in reverse order and the last one executed is the ENV PATH. The next line would be the RUN line which has multiple commands separated by &&.

This is a modification of a Dockerfile on DockerHub. I changed ubuntu versions and the version of the app being installed. That shouldn't have broken anything.

Should I file a bug report?

3 Answers 3

Reset to default
26

First list the "layers" of your finished or incomplete image. Each layer typically corresponds to an instruction in your Dockerfile.

Identify the image ID using

docker image ls

then list the layers inside the image using

docker image history <ID>

You will see something like this:

IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
6c32fe3da793        2 days ago          /bin/sh -c #(nop) COPY file:c25ef1dcc737cb59…   635B                
4c1309db9b9c        2 days ago          /bin/sh -c #(nop) COPY dir:30506cf0fc0cdb096…   8.64kB              
5f5ae40b5fd5        3 weeks ago         /bin/sh -c apk update && apk add --no-cache …   164MB               
989d78741d0b        3 weeks ago         /bin/sh -c #(nop)  ENV DOCKER_VERSION=18.03.…   0B                  
6160911711fc        3 weeks ago         /bin/sh -c #(nop)  CMD ["python3"]              0B                  
... etc

Then create a container from any point inside your image. From there you can perform the next instruction that would cause a problem in your Dockerfile.

Eg:

docker run -it --rm 4c1309db9b9c sh
6
  • 1
    I don't know what your last paragraph means. This is a simple Dockerfile, If I have to do a line by line build like you describe I would say that Docker is broken.
    – Dean Schulze
    Commented Jul 28, 2018 at 4:12
  • 16
    I'm describing how to debug your Dockerfile, which is what I thought you were asking. When you do docker build ., Docker creates a temporary container and runs the instructions listed in your Dockerfile. At the end it creates an image and discards the temporary container. The steps I describe allow you to log into a container at any point in the corresponding Dockerfile. You can inspect your env and perform the steps one by one to isolate the issue and then fix your Dockerfile.
    – Bernard
    Commented Jul 28, 2018 at 4:38
  • I didn't mean to be testy, sorry. I just can't see using a container that would require that kind of intervention. I posted a work around above. Silent failures like this shouldn't happen.
    – Dean Schulze
    Commented Jul 28, 2018 at 4:41
  • once i'm inside the container using the docker run ... command, how do I simulate a COPY from outside the container to inside the container?
    – SuperVeetz
    Commented Feb 17, 2022 at 0:20
  • 1
    i mean, the COPY command doesn't ever finish. Think I figured it out though, you can simulate a COPY by using docker cp <src-file> <container-id>:<inside-container-path> .. seems the VM was out of disk space and node_modules is a mf'er
    – SuperVeetz
    Commented Feb 18, 2022 at 18:01
9

At some point in the last couple of years, Buildkit has become the default Docker backend. Buildkit does not write out intermediate layers as images, as a performance optimization. Therefore, if you need to debug a hanging docker build, comment out the line that the build is hanging at and all subsequent lines. You now have a Dockerfile that you can execute $ docker build . with. Once the build is finished, you can launch the image, bash into the container, run the command that is causing the build to hang and then inspect the state of the container to debug the situation.

1

I got this to work by rolling back to ubuntu 16.04. There must be some change in 18.04 that causes this Dockerfile to fail, or maybe the ubuntu 18.04 image omitted something.

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