I want to create a Docker Image, which includes my ROS packages that I created in catkin_workspace.
I have already tried: create a container form official ros-kinetic-xenial. Create a catkin_workspace and send my packages into it. And create a image with docker commit.
Is there an another way to do that ? (to hold just Binaries and to make image smaller)
thanks
You might want to look into using a Dockerfile to create the image. You can specify a base image and copy files from the build machine into the image. The Dockerfile snippet below configures an image to build off the ros-kinetic base image, then copies a local directory to the image.
FROM ros:kinetic
WORKDIR /docker/path/to/catkin_workspace
ADD /local/path/to/catkin_workspace /docker/path/to/catkin_workspace
Related
I am starting out with programming and am currently working with Docker Containers.
One of the containers is a webserver that takes an input from another container and displays an output on a web page on localhost.
I was wondering if it would be possible to change some comments on the webpage that is part of the container and if so how to go about it?
PS: Pretty new to all this, so please forgive me if I'm asking something really basic
Depends upon the strategy, if you need to change it dynamically when you change the code. You should mount the directory on the container via docker command or docker-compose file. If it is static copy the files via docker file.
It is strange that you are a beginner to programming and are working with docker containers. But now you are here.
Find out if the files you want to edit are part of a container ('baked in') or if they get mounted at container runtime.
If they are baked in, you would go to the bakery (docker build ...) and modify files so that you get modified containers.
If they are mounted at runtime (docker run -v ...) find out where they get mounted from and modify the files over there.
Baked in files cannot be changed just like that, so they reflect an immutable installation. The other files can be changed at runtime. There is no right or wrong, choose the pattern depending on what you want to achieve. That is where the strategy comes into play.
I'm learning Github Actions and designing a workflow with a job that requires a Service Container.
The documentation states that configuration must specify "The Docker image to use as the service container to run the action. The value can be the Docker base image name or a public docker Hub or registry". All of the examples in the docs use publicly-available Docker images, however I want to create a Service Container from a Dockerfile contained within my repo.
Is it possible to use a local Dockerfile to create a Service Container?
Because the job depends on a Service Container, that image must exist when the job begins, and therefore the image cannot be created by an earlier step in the same job. The image could be built in a separate job, but because jobs execute in separate runners I believe that Job 2 will not have access to the image created in Job 1. If this is true then could I follow this approach, using upload/download-artifact so provide Job 1's image to Job 2?
If all else fails, I could have Job 1 create the image and upload it to Docker Hub, then have Job 2 download it from Docker Hub, but surely there is a better way.
The GitHub Actions host machine (runner) is a fully loaded Linux machine, with everything everybody needs already installed.
You can easily launch multiple containers - either your own images, or public images - by simply running docker and docker-compose commands.
My advice to you is: Describe your service(s) in a docker-compose.yml file, and in one of your GitHub Actions steps, simply do docker-compose up -d.
You can create a docker image with the Dockerfile or docker-compose.yml residing inside the repo. Refer to this public gist, it might be helpful.
Instead of building multiple docker-images, you can use docker-compose. Docker-compose is the preferred way to deal with this kind of scenario.
I have problem installing CYGNUS using docker as source, simply i cannot understand where i should map what specific agent.conf.
Image i am using is from here.
When i try to map agent.conf witch have my specific setup to container it starts and run but fail to copy, and not only that any change i made to file inside container wont stay it returns to previous default state.
While i have no issues with grouping_rules.conf using same approach.
I used docker and docker compose both same results.
Path on witch i try to copy opt/apache-flume/conf/agent.conf
docker run -v /home/igor/Documents/cygnus/agent.conf:/opt/apache-flume/conf/agent.conf fiware/cygnus-ngsi
Can some who managed to run it using his config tell me if i misunderstood location of agent.conf or something because this is weird, i used many docker images and never had issue where i was not able to copy from my machine to docker container.
Thanks in advance.
** EDIT **
Link of agent.conf
Did you copy the agent.conf file to your directory before start the container?
As you can see here, when you define a volume with "-v" option, docker copies the content of the host directory, inside the container directory using the mount point. Therefore, you must first provide the agent.conf file on your host.
The reason is that when using a "bind mounted" directory from the
host, you're telling docker that you want to take a file or directory
from your host and use it in your container. Docker should not modify
those files/directories, unless you explicitly do so. For example, you
don't want -v /home/user/:/var/lib/mysql to result in your
home-directory being replaced with a MySQL database.
If you do not have access to the agent.conf file, you can download the template in the source code from the official cygnus github repo here. You can also copy it once the docker container is running, using the docker cp option:
docker cp <containerId>:/file/path/within/container /host/path/target
Keep in mind, that you will have to edit the agent.conf file to configure it according to the database you are using. You can find in the official doc how to configure cygnus to use differents sinks like MongoDB, MySQL, etc.
I hope I have been helpful.
Best regards!
If you look at dockerfiles the often contains lines like this:
sed 's/main$/main universe/' -i /etc/apt/sources.list
I think it is difficult to set up things like this.
Is it possible to launch a default OS image, then enter it interactive with a shell, do some modifications, and then print out the diff (filesystem diff)?
The diff should be used as the dockerfile to recreating the image.
But maybe I am missing something, since I am new to docker.
You can create docker images several ways.
I tend to have two windows open when I create a new docker image. One for my docker run -i -t centos bash, where I am writing all my commands to get it the way I want, and the other one with the Dockerfile, so I can put in whatever I do.
When it comes to config files, I am putting them in the files/folders that matches the one on the image.
Example, if I change /etc/something/file.conf, I will create the file in etc/something/file.conf in the same directory as my Dockerfile, and then use Dockers ADD command to add it whenever I do a build.
This works perfectly, since I can have all this in a git repository with a README.md containing the info I need for running/building the image.
The other thing you can do is to is to run docker ps -a after you are done with the changes you wanted to create an image on, and get the docker ID of the image of the container you just configured. You can tag this new image, or start it with docker run abc0123 bash just like you would a normal docker image.
The problem with this is that you wont be able to easily build it next time without bringing the whole image.
Dockerfiles with ADD is the way to go!
If you do not want to run sed (which is used to preserve the default file and of minimal changes to it), you can simply ADD the modifies file.
For that you can docker run -it --rm thebaseimage /bin/sh (or any other shell that is provided) and edit it in place. Then just copy it outside the container (or docker export it) and use it on your build.
The downside of ADD vs RUN sed… is that, if something changes in a new version of your base image, you will overwrite those changes.
The Dockerfile is (mostly) equivalent to a series of docker run and docker commit commands. You wouldn't want to look at the docker diff to see what files changed -- you'd want to see what docker run commands had occurred. You could get these from your host shell history and process these into a Dockerfile.
I am trying to build an ejabberd container and trying to add 2 files from my build directory while creating the container.
add ./scripts/ /src
However, I keep getting the error: ./scripts folder does not exist
I am new to docker and was hoping for some help.
Thanks,
Arup
The correct syntax for using ADD in Dockerfile is:
ADD <source> <destination>
And ADD has to be in Capital Letters and <source>must be the path to a file or directory relative to the source directory being built (also called the context of the build). So if I wanted to add a file, say "localfile.ext" into a destination folder called "scripts" in the containers, my code in the Dockerfile would be like this:
RUN mkdir /scripts
ADD localfile.ext /scripts/
The trailing / in /scripts/ tells Docker to treat it as a folder else without that /scripts will be treated as a file.
Hope it Helps.