I'm trying to build a ruby-on-rails project, using rails 1.9.3 on Debian image.
After I've built it, using dockerfile, it appears that a directory is missing. So the container doesn't start. So, can I add it manually? I've tried to use "docker run -it sh" to run it as shell, but for some reason, after I add a directory with mkdir it vanishes, when I exit.
I'm kinda new to this stuff (just did some tutorials), so apologize for any mixed up details.
You are going to need to add the dir, and then commit the changes in the container to make a new image out of it to use the directory in the new image. Its much better to use a repeatable DockerFile to create the image
Documentation for DockerFile -> https://docs.docker.com/engine/reference/builder/
Have a look at the documentation for commit here -> https://docs.docker.com/engine/reference/commandline/commit/
Related
I have a weird problem with Docker and hope someone here can help me :)
I want to create a keycloak image that is derived from the image jboss/keycloak. The idea is that in the Dockerfile also a preconfigured standalone.xml is copied into the image and keycloak can start directly without manual work.
But as soon as I write for example a
"CMD touch /opt/test.txt"
into the file the container crashes with the message "12:02:14,290 INFO [org.jboss.modules] (main) JBoss Modules version 1.9.1.Final
WFLYSRV0073: Invalid option '/bin/sh'"
This is just a new file with no purpose, the changes to the .xml are not in there yet.
As soon as I put only the FROM back in and rebuild everything works again.
I thought through the layers in the container you could mod an image, but here it doesn't seem to work. Can someone tell me why ?
So far it has always worked with the alpine image, but I don't want to build the whole keycloak setup again myself, when there is already an official image for it.
This is basically what I had in mind:
FROM jboss/keycloak:X.XX
CMD rm /opt/jboss/keycloak/standalone/configuration/standalone.xml
COPY ./keycloak/standalone.xml /opt/jboss/keycloak/standalone/configuration/
Thanks for help :)
Change
CMD rm
to
RUN rm
RUN is part of building. every RUN command is executed while your image is built.
With CMD you define (or override) the default command when running/starting a container based on your image (and you don't want to change keycloaks default CMD)
I'm trying to deploy the official CGAL docker. From reading the README I understand that after downloading the specific image (e.g I want to open a docker with ubuntu16+CGAL and all of it's dependencies) using the following command:
docker pull cgal/testsuite-docker:ubuntu # get a specific image by replacing TAG with some tag
I need to install the cgal library itself using the
./test_cgal.py --user **** --passwd **** --images cgal-testsuite/ubuntu
The thing is that eventually I want to start the docker with an interactive shell, i.e
docker run --rm -it -v $(pwd):/source somedocker
And I couldn't understand where is the generated image, after the CGAL installation script.
Those images are not for running CGAL. They are only images we use to define an environment for our testsuite, and run tests in it, including compiling CGAL.
test_cgal.py will download the integration branch, which is rarely working as it is the branch in which we merge our PR to test them nightly. Don't use this to get a working CGAL. To my knowledge, there is no such image as the one you are looking for. No official one anyways.
Furthermore, installing cgal at runtime in this image will not modify the image, once you close the container your installation will be lost. You need to specify how to install CGA in the Dockerfile of your image and
then build it if you want a "ready to use" image.
You can use the dockerfile of the image you found to write your own, as there should be all the dependencies specified in it, but you need to edit it to download CGAL and maybe build it if you don't want the header-only version. This is not done in test-cgal.py or anywhere in this docker repository.
I need to create a Docker image, which when run, should install an exe in the specified directory that mentioned in my docker file.
Basically, I need ImageMagick application. The docker file created should be platform independent, say if I ran in windows it should use windows distribution, Linux means Linux distribution. It would be great if it adds an environmental variable in the system. I browsed for the solution, but I couldn't find an appropriate solution.
I know it's a bit late but maybe someone (like me) was still searching.
I ended up using a java-imagemagick docker version from https://hub.docker.com/r/cpaitsupport/java-imagemagick/dockerfile
You can run docker pull cpaitsupport/java-imagemagick to get this docker image to your docker machine.
Now comes the tricky part: as I needed to run the imagemagick inside a docker container for my main app. Now you can COPY the files from cpaitsupport/java-imagemagick to your custom container. Example :
COPY --from=cpaitsupport/java-imagemagick:latest . ./some/dir/imagemagick
now you should have the docker file structure for your custom app and also under some/dir/imagemagick/ the file structure for imagemagick. Here are all ImageMagick relative files (also convert, magic, the libraries etc).
Now if you want to use ImageMagick in your Code you need to setup some ENV variables to your docker container with the "new" path to the ImageMagick directory. Example:
IM4JAVA_TOOLPATH=/some/dir/imagemagick/usr/bin \
LD_LIBRARY_PATH=/usr/lib:/some/dir/imagemagick/usr/lib \
MAGICK_CONFIGURE_PATH=/some/dir/imagemagick/etc/ImageMagick-7 \
MAGICK_CODER_MODULE_PATH=/some/dir/imagemagick/usr/lib/ImageMagick-7.0.5/modules-Q16HDRI/coders \
MAGICK_HOME=/some/dir/imagemagick/usr
Now delete (in Java Code) ProcessStarter.setGlobalSearchPath(imPath); this part if it is set. So you can use the IM4JAVA_TOOLPATH.
Now the ConvertCmd cmd = new ConvertCmd(); and cmd.run(op); should be working.
Maybe it's not the best way but worked for me and I was struggling a lot.
Hope this helps!
Feel free to correct or add additional info.
You can install (extract files) to the external hosting system using docker mount or volumes -
however you can not change system setting by updating environment variables of the hosting system from inside of the containers.
From the following image: https://registry.hub.docker.com/u/cloudesire/activemq/dockerfile/
If I wanted to override the ACTIVEMQ_VERSION environment variable in my child docker file, I assumed I would be able to do something like the following:
FROM cloudesire/activemq:latest
MAINTAINER abc <abc#xyz.co.uk>
ENV ACTIVEMQ_VERSION 5.9.1
ADD ./src/main/resources/* /opt/activemq/conf/
However this does not seem to work. Admittedly I am new to Docker and have obviously misunderstood something. Please could someone explain why this does not work, and how/if I can achieve it another way?
That won't work. The ACTIVEMQ_VERSION has already been used by the cloudesire/activemq:latest image build to populate its image layers. All the ActiveMQ installation files based on version 5.11.1 are already extracted in their corresponding directories.
In your Dockerfile you only can build on top of what has already been build there and add your files. Your own Dockerfile build will not re-run the build instructions described in their Dockerfile.
If you need to have your own cloudesire/activemq image based on version 5.9.1 you need to clone their Dockerfile, adjust the version there and build it locally. So you could base your other Dockerfile on it.
According to the Docker documentation, to build your own image, you must always specify a base image using the FROM instruction.
Obviously, there are lots of images to choose from in the Docker index, but what if I wanted to build my own? Is that possible?
The image base is built off Ubuntu if I understand correctly, and I want to experiment with a Debian image. Plus, I want to really understand how Docker works, and the base image is still a blackbox for me.
Edit: official documentation on creating a base image
You can take a look at how the base images are created and go from there.
You can find them here: https://github.com/dotcloud/docker/tree/master/contrib.
There is mkimage-busybox.sh, mkimage-unittest.sh, mkimage-debian.sh
Quoting Solomon Hykes:
You can easily create a new container from any tarball with "docker import". For example:
debootstrap raring ./rootfs
tar -C ./rootfs -c . | docker import - flimm/mybase
(credit to fatherlinux) Get information from https://developers.redhat.com/blog/2014/05/15/practical-introduction-to-docker-containers/ , which explains better
Create the tar files for your file system, simply could be
tar --numeric-owner --exclude=/proc --exclude=/sys -cvf centos6-base.tar /
Transfer the tar file to other docker system if not installed locally and import it
cat centos6-base.tar | docker import - centos6-base
Now you can verify by running it.
docker run -i -t centos6-base cat /etc/redhat-release
The scripts from dotcloud combine first two steps together which make me confused and looks complicated in the beginning.
The docker official guideline using debootstrap also tries to make clean file system.
You can judge by yourself how to do step 1.
To start building your own image from scratch, you can use the scratch image.
Using the scratch “image” signals to the build process that you want the next command in the Dockerfile to be the first filesystem layer in your image.
FROM scratch
ADD hello /
CMD ["/hello"]
http://docs.docker.com/engine/articles/baseimages/#creating-a-simple-base-image-using-scratch
If you want to make your own base image I would first take a look at
Official Images, specifically stackbrew inside that repo.
Otherwise there are some great references for minimal OS images in the docker repo itself.
For example here is a script for making a minimal arch image and there are more here.