I am trying to create a normal docker's container, where I want to run my awk script. So we came to know we have to install GNU awk in it too, so could you please let me know if there any way we could get it in container itself(which creating os image) rather than installing it separately:
I apologies if I missed something here as I am new to this technology.
There are a couple of gawk-installed docker images publicly available. You may directly use one of them. A few examples: atarumix/gawk5-alpine algas/gawk. I have to note that most (if not all) are not actively maintained.
You may create a Dockerfile and install gawk. Although you mentioned you do not want to have a separate install, it is pretty easy. Consider this for example:
FROM alpine:latest
RUN apk add --no-cache gawk ffmpeg
If you do not want to use that docker file, you may push the generated image to an image repository. After you push the image, you shall be able to use the image directly. Details of push can be found at push reference.
Related
I hope you are doing well.
I'm trying to rebuild a docker image.
What I mean is, I don't just want to get some files into the file system of the image, but want to edit the source code/the codebase itself... whatever it's called.
Especially, I'd like to make the image instances leave some log information.
But I'm totally clueless what to edit(even I can't find the source base code of that image)
Could you please help me edit the source code if you know how?
I would really appreciate. Thank you in advance.
I'd like to make the image instances leave some log information
This requirement may be reached with bind mounts:
$ docker run -d \
-it \
--name container-name \
-v "$(pwd)"/logs:/app/logs \
your-image
Here, $(pwd)/logs is a directory on your host filesystem that will contain the logs, and /app/logs is a directory that your application uses to write logs inside the container. Of course, you need to modify these according to your needs.
The other requirement might as well be achieved in a similar way:
I don't just want to get some files into the file system of the image, but want to edit the source code/the codebase itself
It depends on the tech stack you use for development. For example, if your app is written in PHP, you can mount source code folder to the container, and each time you modify a file, the same version will "appear" inside the container, since PHP is an interpreted language that does not require compilation.
If you use, for example, Go, this will not work the same way, since Go programs require compilation, and it is not enough to update source code inside the container. In such case you'll have to build the image again each time you need to make a change.
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.
First off, I really lack a lot of knowledge regarding Docker itself and its structure. I know that it'd be way more beneficial to learn the basics first, but I do require this to work in order to move on to other things for now.
So within a Dockerfile I installed wget & used it to download a file from a website, authentification & download are successful. However, when I later try move said file it can't be found, and it doesn't show up using e.g explorer either (path was specified)
I thought it might have something to do with RUN & how it executes the wget command; I read that the Id can be used to copy it to harddrive, but how'd I do that within a Dockerfile?
RUN wget -P ./path/to/somewhere http://something.com/file.txt --username xyz --password bluh
ADD ./path/to/somewhere/file.txt /mainDirectory
Download is shown & log-in is successful, but as I mentioned I am having trouble using that file later on as it's not to be located on the harddrive. Probably a basic error, but I'd really appreciate some input that might lead to a solution.
Obviously the error is produced when trying to execute ADD as there is no file to move. I am trying to find a way to mount a volume in order to store it, but so far in vain.
Edit:
Though the question is similiar to the "move to harddrive" one, I am searching for ways to get the id of the container created within the Dockerfile in order to move it; while the thread provides such answers, I haven't had any luck using them within the Dockerfile itself.
Short answer is that it's not possible.
The Dockerfile builds an image, which you can run as a short-lived container. During the build, you don't have (write) access to the host and its file system. Which kinda makes sense, since you want to build an immutable image from which to run ephemeral containers.
What you can do is run a container, and mount a path from your host as a volume into the container. This is the only way how you can share files between the host and a container.
Here is an example how you could do this with the sherylynn/wget image:
docker run -v /path/on/host:/path/in/container sherylynn/wget wget -O /path/in/container/file http://my.url.com
The -v HOST:CONTAINER parameter allows you to specify a path on the host that is mounted inside the container at a specified location.
For wget, I would prefer -O over -P when downloading a single file, since it makes it really explicit where your download ends up. When you point -O to the location of the volume, the downloaded file ends up on the host system (in the folder you mounted).
Since I have no idea what your image or your environment looks like, you might need to tweak one or two things to work well with your own image. As a general recommendation: For basic commands like wget or curl, you can find pre-made images on Docker Hub. This can be quite useful when you need to set up a Continuous Integration pipeline or so, where you want to use wget or curl but can't execute it directly.
Use wget -O instead of -P for specific file download
for e.g.,
RUN wget -O /tmp/new_file.txt http://something.com --username xyz --password bluh/new_file.txt
Thanks
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.